- Isothiourea-catalyzed enantioselective α-alkylation of esters via 1,6-conjugate addition to para-quinone methides
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The isothiourea-catalyzed enantioselective 1,6-conjugate addition of para-nitrophenyl esters to 2,6-disubstituted para-quinone methides is reported. para-Nitrophenoxide, generated in situ from initial N-acylation of the isothiourea by the para-nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of para-nitrophenyl ester products can be isolated, or derivatized in situ by addition of benzylamine to give amides at up to 99% yield. Although low diastereocontrol is observed, the diastereoisomeric ester products are separable and formed with high enantiocontrol (up to 94:6 er).
- Arokianathar, Jude N.,Greenhalgh, Mark D.,Hartley, Will C.,McLaughlin, Calum,Ng, Sean,Slawin, Alexandra M. Z.,Smith, Andrew D.,Stead, Darren
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supporting information
(2021/11/01)
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- Preparation method of 4-phenyl methylene-2, 6-di-tert-butyl-2, 5-cyclohexadiene-1-ketone and derivative thereof
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The invention provides a preparation method of 4-phenyl methylene-2, 6-di-tert-butyl-2, 5-cyclohexadiene-1-ketone and a derivative thereof, and the method comprises the following steps: reacting aromatic aldehyde, secondary amine and lewis acid in a solvent, adding a 2, 6-disubstituted phenol solution, and continuing to react to obtain a reaction solution; and washing the reaction solution and separating an organic layer to obtain the 4-phenyl methylene-2, 6-di-tert-butyl-2, 5-cyclohexadiene-1-ketone and the derivatives thereof. The method can reduce the reaction temperature, shorten the reaction time, reduce the generation of byproducts, avoid the generation of three wastes, and is green and environment-friendly.
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Paragraph 0036-0047
(2021/05/05)
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- Vinylogous Aza-Michael Addition of Urea Derivatives with p-Quinone Methides Followed by Oxidative Dearomative Cyclization: Approach to Spiroimidazolidinone Derivatives
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Herein, we report an efficient protocol for the synthesis of spiro-imidazolidinone-cyclohexadienones from p-quinone methides (p-QMs) and dialkyloxy ureas under mild conditions. The strategy follows a two-step process involving an initial vinylogous conjugate addition of urea derivatives to p-QMs, followed by oxidative dearomative cyclization of open-chain product to the projected spiro-imidazolidinones. This protocol exhibits good functional group tolerance and provides a straightforward method to access spiro-imidazolidinone-cyclohexadienones. In follow-up chemistry, we have shown the debenzylation of spiroimidazolidinones to give N-hydroxycyclic ureas. (Figure presented.).
- Kaur, Navpreet,Singh, Priyanka,Banerjee, Prabal
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supporting information
p. 2813 - 2824
(2021/04/21)
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- Enantioselective Stetter Reactions Catalyzed by Bis(amino)cyclopropenylidenes: Important Role for Water as an Additive
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The first highly enantioselective intermolecular Stetter reaction using simple enones is reported. A series of novel chiral BAC structures were designed and prepared. They were tested in the Stetter reaction with simple aldehydes and enones. The products were generated in excellent yields and enantioselectivities (up to 94% ee). Surprisingly, a substoichiometric amount of water was crucial to obtain high enantioselectivities. Chiral BACs were also shown to catalyze 1,6-conjugate addition reactions with paraquinone methides enantioselectively.
- Rezazadeh Khalkhali, Mehran,Wilde, Myron M. D.,Gravel, Michel
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supporting information
p. 155 - 159
(2021/01/09)
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- Metal-Free, Acid/Phosphine-Induced Regioselective Thiolation of p-Quinone Methides with Sodium Aryl/Alkyl Sulfinates
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A simple and efficient method for the regioselective thiolation of p-quinone methides with sodium aryl/alkyl sulfinates has been established using an acid/phosphine-induced radical route under transition-metal-free conditions. A broad range of sodium aryl/alkyl sulfinates and p-quinone methides (p-QMs) are compatible for the reaction, giving the expected products with good to excellent yields. Control experiments were also performed to gain insights into the generation mechanism of thiyl radicals and hydrogen-atom transfer process. This protocol provides a safe and feasible way for the formation of carbon-sulfur bonds.
- Xiong, Biquan,Xu, Shipan,Liu, Yu,Tang, Ke-Wen,Wong, Wai-Yeung
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p. 1516 - 1527
(2021/02/03)
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- Synthetic method of diaryl methyl sulfide derivatives catalyzed by organic phosphine
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The invention provides a synthetic method of diaryl methyl sulfide derivatives catalyzed by organic phosphine. The synthetic method comprises the following steps: with tris(4-fluorophenyl)phosphorus as a catalyst and methanol as a solvent, subjecting substrates as shown in a formula I and a formula II to reacting at normal temperature for 24 hours, and carrying out column chromatography separation to obtain a product as shown in a formula III. The invention provides the synthetic method of a plurality of related new derivatives, and the substrates of the method have good universality. According to the method, tris(4-fluorophenyl)phosphorus is used as a catalyst, the substrate I and the substrate II are subjected to a thia-1,6-conjugate addition reaction, multiple diaryl methyl sulfide derivatives with uniformly distributed substituent groups are obtained, and the method is simple in process and operation process, high in product yield, mild in conditions, low in raw material cost, friendly to environment, low in energy consumption, low in equipment requirement and good in substrate applicability, has a great utilization prospect and can be applied to large-scale production by adopting a specific implementation mode.
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Paragraph 0037; 0053-0054
(2021/07/01)
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- Phosphine-Catalyzed Intermolecular Dienylation of Alkynoate with para-Quinone Methides
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An interesting remote I-C 1,6-Addition and an isomerization cascade reaction for phosphine-catalyzed activated alkynes have been disclosed. The products featuring a functional diene and a 1,1-diaryl methyl motif have been obtained in moderate to good yields (30-86%) by applying para-quinone methides (p-QMs) and I-substituted alkynoate with tributylphosphine (PnBu3) catalysis, along with high regioselectivity and stereoselectivity (dr > 20:1). The wide scope of compatible substrates (35 examples), such as indolyl, oxindolyl, ester, and cinnamyl, expand the utility of this methodology. A plausible mechanism and some applications of it have also been presented.
- Song, Zefeng,Wang, Weijia,Liu, Zhixin,Lu, Yue,Wang, De
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supporting information
p. 8590 - 8599
(2021/07/20)
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- Thiourea catalyzed 1,6-conjugate addition of indoles to para-quinone methides
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An efficient thiourea catalyzed 1,6-conjugate addition of indoles to para-quinone methides (p-QMs) was developed. p-QMs was activated by a weak hydrogen-bond effect. The reaction is featured mild reaction conditions and wide substrate scope. A series of C-3 bisaryl methine substituted indoles are prepared in high yield.
- Wu, Guangmiao,Li, Tao,Liu, Fuhai,Zhao, Yulong,Ma, Shiqiang,Tang, Shouchu,Xie, Xingang,She, Xuegong
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supporting information
(2021/09/09)
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- Metal-free, Tf2NH-catalyzed 1, 6-conjugate addition of imidazopyridine to para-quinone methides: Easy access to C3-functionalized triarylmethane imidazopyridine
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An inexpensive and commercially available Tf2NH-catalyzed 1,6-conjugate addition of imidazopyridine (IMPY) heterocycles to para-quinone methides (p-QMs) is reported. The present transformation provides a diverse class of C3-functionalized triarylmethanes heterocyclic derivatives of imidazopyridine. These metal-free transformations provided a very broad substrate scope of conjugate addition product with a high yield up to 97% within a short duration.
- Khonde, Nilesh S.,Said, Madhukar S.,Sabane, Jagjivan K.,Gajbhiye, Jayant M.,Kumar, Pradeep
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supporting information
(2021/10/30)
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- Silver-Catalyzed Regioselective Phosphorylation of para-Quinone Methides with P(III)-Nucleophiles
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A simple and efficient method for the silver-catalyzed regioselective phosphorylation of para-quinone methides (p-QMs) with P(III)-nucleophiles (P(OR)3, ArP(OR)2, Ar2P-OR) has been established via Michaelis-Arbuzov-type reaction. A broad range of P(III)-nucleophiles and para-quinone methides are well tolerated under the mild conditions, giving the expected diarylmethyl-substituted organophosphorus compounds with good to excellent yields. Moreover, a series of corresponding enantiomers can be obtained by employing dialkyl arylphosphonite (ArP(OR)2) as substrates. The control experiments and 31P NMR tracking experiments were also performed to gain insights for the plausible reaction mechanism. This protocol may have significant implications for the formation of C(sp3)-P bonds in Michaelis-Arbuzov-type reactions.
- Liu, Yu,Tang, Ke-Wen,Wong, Wai-Yeung,Xie, Jun,Xiong, Biquan,Xu, Shipan,Xu, Weifeng
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p. 14983 - 15003
(2021/11/12)
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- Organocatalytic Enantioselective 1,6-aza-Michael Addition of Isoxazolin-5-ones to p-Quinone Methides
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A thiourea-Br?nsted base bifunctional catalyst allowed the enantioselective 1,6-aza-Michael addition of isoxazolin-5-ones to p-quinone methides to give isoxazolin-5-ones having a chiral diarylmethyl moiety attached to the N atom with fair to good yields and enantiomeric excesses. To the best of our knowledge this reaction represents the first example of enantioselective N-alkylation of isoxazolin-5-ones as well as the first example of enantioselective 1,6-aza-Michael reaction involving p-quinone methides.
- Torán, Ricardo,Vila, Carlos,Sanz-Marco, Amparo,Mu?oz, M. Carmen,Pedro, José R.,Blay, Gonzalo
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supporting information
p. 627 - 630
(2020/02/05)
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- Lipase-Catalyzed Highly Efficient 1,6-Conjugated Addition for Synthesis of Triarylmethanes
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Lipase from porcine pancreas (PPL) is first reported to catalyze direct 1,6-conjugated addition for synthesis of triarylmethanes using p-quinonemethides (p-QMs) and 2-naphthols. The catalytic activity of PPL was evaluated through investigating the solvent, the ratio of substrates, the enzyme loading and the temperature of the enzyme-catalyzed reactions. The present method proves to be environmentally friendly and efficient in terms of high yield, green catalyst and simple synthesis method. GraphicAbstract: [Figure not available: see fulltext.]
- Yang, Zeng-Jie,Wang, Na,He, Wei-Xun,Yu, Yuan,Gong, Qing-Tian,Yu, Xiao-Qi
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p. 1268 - 1276
(2019/12/11)
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- TBAB-catalyzed 1,6-conjugate sulfonylation of paraquinone methides: A highly efficient approach to unsymmetrical gem-diarylmethyl sulfones in water ?
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A highly efficient sulfonylation of para-quinone methides with sulfonyl hydrazines in water has been developed on the basis of the mode involving a tetrabutyl ammonium bromide (TBAB)-promoted sulfa-1,6-conjugated addition pathway. This reaction provides a green and sustainable method to synthesize various unsymmetrical diarylmethyl sulfones, showing good functional group tolerance, scalability, and regioselectivity. Further transformation of the resulting diarylmethyl sulfones provides an efficient route to some functionalized molecules.
- Liu, Zhang-Qin,You, Peng-Sheng,Zhang, Liang-Dong,Liu, Da-Qing,Liu, Sheng-Shu,Guan, Xiao-Yu
-
supporting information
(2020/02/11)
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- Visible-light-promoted radical cross-coupling of: Para-quinone methides with N-substituted anilines: An efficient approach to 2,2-diarylethylamines
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An efficient protocol to access 2,2-diarylethylamines via visible-light-promoted radical reactions of para-quinone methides (p-QMs) with N-alkyl anilines has been disclosed. These reactions feature metal-free, redox-neutral, and mild reaction conditions with wide functional group compatibility.
- Wu, Qiao-Lei,Guo, Jing,Huang, Gong-Bin,Chan, Albert S. C.,Weng, Jiang,Lu, Gui
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supporting information
p. 860 - 864
(2020/02/15)
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- The strategic use of: Para-quinone methides to access synthetically challenging and chemoselective α,α-diarylmethyl N-glycosides from unprotected carbohydrate amines
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Reported herein is a practical route to access synthetically challenging and chemoselective α,α-diarylmethyl N-glycosides via Sc(OTf)3-catalyzed 1,6-conjugate addition of amino sugars with para-quinone methides (p-QMs). The reactions proceed smoothly without a base and under mild reaction conditions with a broad substrate scope and moderate to good yields.
- Sangwan, Rekha,Dubey, Atul,Tiwari, Ashwani,Mandal, Pintu Kumar
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supporting information
p. 1343 - 1348
(2020/03/03)
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- Base-promoted 1,6-conjugate addition of alkylazaarenes topara-quinone methides
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1,1,2-Triarylethanes embedded with an azaarene unit were prepared in a single step at ambient temperatureviathe sodium hexamethyldisilazide mediated 1,6-conjugate addition of unactivated alkylazaarenes onpara-quinone methides (p-QMs). The extent of this methodology was investigated with a wide range ofp-QMs and alkylazaarenes, and the respective products were obtained in moderate to excellent yields. The regioselective 1,6-conjugate addition of the trialkylazaarene precursor onpara-quinone methide was also presented. Besides, we showcased the direct synthesis of the 1,1,2-triarylethane derivative from aldehydeviathein situgeneration ofpara-quinone methide.
- A. V., Kalyanakrishnan,Hari, Krishna,Kaliyamoorthy, Alagiri,Rayaroth, Amritha,Singh, Rajat Kumar
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supporting information
p. 3354 - 3359
(2020/05/14)
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- An Efficient One-Pot Protocol for Direct Access to Diarylmethyl Thioglycosides with para -Quinone Methides via S -Glycosyl Isothiouronium Salts
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An efficient one-pot protocol has been developed for the direct preparation of diarylmethyl thioglycosides starting from per-O-acetylated sugars via glycosyl isothiouronium salts. The one-pot reaction conditions involve rapid conversion of the per-O-acetylated sugar with thiourea in the presence of boron trifluoride etherate as catalyst to give the corresponding glycosyl isothiouronium salt, which is subsequently treated with a para -quinone methide in the presence of a base to give the a diarylmethyl thioglycoside in excellent yield.
- Dubey, Atul,Mandal, Pintu Kumar
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supporting information
p. 1713 - 1719
(2020/07/24)
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- Ammonium Chloride-Mediated Trifluoromethylthiolation of p-Quinone Methides
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Ammonium chloride-mediated trifluoromethylthiolation of p-quinone methides is reported using inexpensive and bench stable AgSCF3 as a nucleophilic trifluoromethylthiolating (-SCF3) reagent. This method is an efficient strategy for the construction of the benzylic C(sp3)-SCF3 bond to synthesize trifluoromethylthio-diarylmethane derivatives by 1,6-conjugate addition/aromatization under mild reaction conditions without any metal catalyst, oxidants, or additives. This is the first report of trifluoromethylthiolation of p-quinone methides. In addition, di-trifluoromethylthiolation of δ-chloro-p-quinone methide and scalability are demonstrated.
- Das, Debabrata,Ghosh, Krishna Gopal,Chandu, Palasetty,Sureshkumar, Devarajulu
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p. 14201 - 14209
(2020/11/13)
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- Visible-Light-Enabled C?H Functionalization by a Direct Hydrogen Atom Transfer Uranyl Photocatalyst
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The development of the uranyl cation as a powerful photocatalyst is seriously delayed in comparison with the advances in its fundamental and structural chemistry. However, its characteristic high oxidative capability in the excited state ([UO2]2+* (+2.6 V vs. SHE; SHE=standard hydrogen electrode) combined with blue-light absorption (hv=380–500 nm) and a long-lived fluorescence lifetime up to microseconds have reveals that the uranyl cation approaches an ideal photocatalyst for visible-light-driven organic transformations. Described herein is the successful use of uranyl nitrate as a photocatalyst to enable C(sp3)?H activation and C?C bond formation through hydrogen atom transfer (HAT) under blue-light irradiation. In particular, this operationally simple strategy provides an appropriate approach to the synthesis of diverse and valuable diarylmethane motifs. Mechanistic studies and DFT calculations have provided insights into the detailed mechanism of the photoinduced HAT pathway. This research suggests a general platform that could popularize promising uranyl photocatalytic performance.
- Chai, Zhifang,Chen, Siyu,Gao, Wenchao,Hu, Hanshi,Hu, Kongqiu,Liu, Kang,Mei, Lei,Shi, Weiqun,Wang, Shuai,Yu, Jipan,Yuan, Liyong,Zhao, Chongyang,Zhou, Rong
-
supporting information
p. 16521 - 16529
(2020/12/01)
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- Solvent-free microwave synthesis 4 - phenyl methylene - 2, 6 - di-tert-butyl - 2, 5 - cyclohexadiene -1 - ketone (by machine translation)
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The invention discloses a 4 - benzylidene - 2, 6 - di-tert-butyl - 2, 5 - cyclohexadiene - 1 - ketone derivative (P -QM) green preparation method. Under the condition of using solvent-free microwave radiation heating, 2, 6 - di-tert-butyl phenol and aldehyde, through the Mannich condensation and [...] two-step reaction, to obtain the 4 - benzylidene - 2, 6 - di-tert-butyl - 2, 5 - cyclohexadiene - 1 - ketone derivative (P -QM). This method has the raw material is cheap, the atom economy is high, fast reaction time, environment friendly, without the use of hazardous reagent and solvent, synthetic step is simple and convenient and the like, and the mild reaction conditions, substrate range wide applicability, simple and safe operation, and is suitable for industrial production. (by machine translation)
- -
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Paragraph 0015-0017
(2019/04/30)
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- Recycling piperidine preparation 4 - benzylidene - 2, 6 - di-tert-butyl - 2, 5 - cyclohexadiene -1 - one method (by machine translation)
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Recycling piperidine preparation 4 - benzylidene - 2, 6 - di-tert-butyl - 2, 5 - cyclohexadiene - 1 - one method, which belongs to the technical field of organic synthesis. The method in order to 2, 6 - di-tert-butyl phenol and benzaldehyde as the starting material, dropping piperidine, in the piperidine salt under catalysis of the reaction, generating Mannich bases, then adding the same with catalyst acid, product and piperidine hydrochloride, piperidine hydrochloride adding sodium hydroxide solution and in re-extraction recovery piperidine, a certain amount of added piperidine directly used for the next synthesis of the kettle. The method of the invention can be under conventional conditions for preparing 4 - benzylidene - 2, 6 - di-tert-butyl - 2, 5 - cyclohexadiene - 1 - one, intermediate does not need to separate purification, piperidine recycling, the operation is safe, simple, saving energy. The method starting raw materials are cheap and has been industrialization, help to guarantee the supply of raw materials, the production cost is reduced. Each reaction can be carried out at normal pressure, the process is simple, low energy consumption, the operation is convenient, it is suitable for industrial scale production. (by machine translation)
- -
-
Paragraph 0049; 0050; 0052; 0053; 0055; 0056; 0058; 0059
(2019/02/27)
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- A contains the cyano benzofuran synthetic method and use thereof
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The invention discloses a contains the cyano benzofuran compound synthesis method, in order to benzofuran - 2 - ketone compound as the reaction initiator, to EtOH as the solvent, in the 0 °C condition and slowly adding reducing agent NaBH4 , Then stirring at room temperature the reaction, water quenching, product of ethyl acetate extraction after the saturated salt water for washing, collecting the organic layer, dried, concentrated, column chromatography or thin layer chromatography to obtain intermediate benzofuran - 2 - ol; to benzofuran - 2 - ol as raw materials, AlCl3 As additive, benzene as solvent, in the environment of nitrogen for 60o The reaction is stirred under the condition C 2 h, water quenching, the obtained product of ethyl acetate extraction, collection of the organic layer, dried, concentrated, column chromatography or thin layer chromatography separation purification to obtain the target product, synthetic reaction of simple operation, the price of reagent of cheap and easily obtained, mild reaction system, condition is simple, and good yield, has better popularization and application value.
- -
-
Paragraph 0007; 0008
(2019/07/04)
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- Visible-light mediated trifluoromethylation of p-quinone methides by 1,6-conjugate addition using pyrylium salt as organic photocatalyst
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A transition metal free visible light mediated organo photoredox catalyzed trifluoromethylation of p-quinone methides (p-QMs) to construct fluoro-analogs of dichlorodiphenyltrichloroethane (DDT) is reported using a bench stable, inexpensive Langlois reagent as a trifluoromethyl radical source. This protocol could generate a benzylic C(sp3)-CF3 bond with excellent yield under mild reaction conditions using 1,6-conjugate addition/aromatization of trifluoromethyl radical in the absence of any external additives. Further, we demonstrate di-trifluoromethylation and gram scale synthesis of this reaction.
- Ghosh, Krishna Gopal,Chandu, Palasetty,Mondal, Santanu,Sureshkumar, Devarajulu
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p. 4471 - 4478
(2019/07/09)
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- Synthetic method of asymmetric triarylmethane derivative
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The invention discloses a synthetic method of an asymmetric triarylmethane derivative. In the method, p-methylene benzoquinone or a derivative thereof and 2-hydroxynaphthol are adopted as raw materials. (C4H12N2)2[BiCl6]Cl.H2O is adopted as a catalyst, a one-step reaction is performed at room temperature under the condition of a dichloromethane solvent to obtain the asymmetric triarylmethane derivative. Compared with the prior art, the v method is simple and convenient to operate and short in reaction time; the catalyst is high in activity and can be repeatedly recycled; the substrate range iswide, and the production cost is low; the yield of the target compound is high; and the method is environment-friendly and wide in industrial production prospect.
- -
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Paragraph 0019-0020
(2019/12/02)
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- Unravelling the Nucleophilicity of Butenolides for 1,6-Conjugate Addition to p-Quinone Methides: A Direct Access to Diversely Substituted Butenolide-Derived Diarylmethanes
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A Lewis acid catalyzed regioselective C-C bond is constructed through β-addition of deconjugated butenolides with p-quinone methides in a 1,6-conjugate addition manner. Interestingly, Lewis acid catalyzed vinylogous Mukaiyama-Michael reaction of silyloxyfurans with p-QMs proceeds selectively through the α or γ position exclusively. The reaction is mild with broad substrate scope, thus allowing easy access to a wide range of bis-arylated α-/β-/γ-substituted butenolides.
- Sharma, Brijesh M.,Shinde, Dinesh R.,Jain, Ruchi,Begari, Eeshwaraiah,Satbhaiya, Shruti,Gonnade, Rajesh G.,Kumar, Pradeep
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supporting information
p. 2787 - 2791
(2018/05/17)
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- Harnessing Nucleophilicity of Allenol Ester with p-Quinone Methides via Gold Catalysis: Application to the Synthesis of Diarylmethine-Substituted Enones
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A gold(I)-catalyzed protocol for intermolecular 1,6-conjugate addition of nucleophilic allenol ester generated in situ through [3,3]-sigmatropic rearrangement with p-quinone methides (p-QMs) has been developed. The gold catalyst plays a dual role by the acid-triggered activation of alkynes and at the same time as a Lewis acid for activation of p-QMs toward nucleophilic attack. This method enables rapid access to a wide range of densely functionalized diarylmethine-substituted enones, a Morita-Baylis-Hillman (MBH) product with high selectivity, excellent yields, and broad substrate scope.
- Sharma, Brijesh M.,Rathod, Jayant,Gonnade, Rajesh G.,Kumar, Pradeep
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p. 9353 - 9363
(2018/06/29)
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- Gold-catalyzed tandem reaction of 2-alkynylanilines followed by 1,6-conjugate addition to: P -quinone methides: Efficient access to unsymmetrical diarylindolylmethanes
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A simple, mild, efficient and chemoselective catalytic method for the straightforward synthesis of an interesting class of 2-aryl/alkyl-substituted-3-diaryl indolyl methanes in high yield is reported. This atom-efficient method proceeds via a gold-catalyzed one-pot sequential intramolecular hydroamination (C-N bond formation) of 2-alkynylanilines followed by a 1,6-conjugate addition to p-quinonemethides. The p-quinonemethides, which contain aldehyde functional groups, preferentially participate in 1,6-conjugate addition, while the aldehyde functional group remains unreactive.
- Jillella, Raveendra,Oh, Dong Hwan,Oh, Chang Ho
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supporting information
p. 16886 - 16890
(2018/10/23)
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- A new approach to access difluoroalkylated diarylmethanes: Via visible-light photocatalytic cross-coupling reactions
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Difluoroalkylated diarylmethanes with biological and pharmacological potentials were synthesized from para-quinone methides (p-QMs) and difluoroalkylating reagents via a visible light photocatalysis strategy. Mechanism studies showed that the excited photocatalyst, ?fac-Ir(ppy)3, was primarily quenched by p-QMs and the generated diarylmethane radical intermediates then underwent a radical-radical cross-coupling reaction with difluoroalkyl radicals. This reaction features mild conditions, high efficiency and wide functional group compatibility.
- Zhao, Yin-Na,Luo, Yong-Chun,Wang, Zhu-Yin,Xu, Peng-Fei
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supporting information
p. 3993 - 3996
(2018/04/23)
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- Silver-Catalyzed Cascade 1,6-Addition/Cyclization of para-Quinone Methides with Propargyl Malonates: An Approach to Spiro[4.5]deca-6,9-dien-8-ones
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An unprecedented silver-catalyzed cascade 1,6-addition/5-exo-dig cyclization reaction between para-quinone methides and propargyl malonates under mild reaction conditions has been described. This reaction provides an efficient method to construct versatile spiro[4.5]cyclohexadienones in moderate to excellent yields with high atom economy and scalability.
- Yuan, Zhenbo,Liu, Lina,Pan, Rui,Yao, Hequan,Lin, Aijun
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p. 8743 - 8751
(2017/08/23)
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- Copper-Catalyzed 1,6-Hydrodifluoroacetylation of para-Quinone Methides at Ambient Temperature with Bis(pinacolato)diboron as Reductant
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An original and efficient copper-catalyzed 1,6-hydrodifluoroacetylation of para-quinone methides with difluoroalkyl bromides has been described with bis(pinacolato)diboron (B2pin2) as reductant. In this reaction, a new C(sp3)–CF2bond is constructed under smart conditions. A broad substrate scope of para-quinone methides (p-QMs) make this protocol very practical and attractive. Preliminary mechanistic studies manifested that a difluoroalkyl radical pathway was involved in this reaction. Also the presence of the diboron reagent was an essential requisite in this transformation. (Figure presented.).
- Ke, Miaolin,Song, Qiuling
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p. 384 - 389
(2017/02/10)
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- Enantioselective Spirocyclopropanation of para-Quinone Methides Using Ammonium Ylides
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The use of Cinchona alkaloid-based chiral ammonium ylides allows for the first highly enantioselective and broadly applicable spirocyclopropanation reactions of para-quinone methides. This strategy provides a straightforward protocol toward the chiral spiro[2.5]octa-4,7-dien-6-one skeleton, which is a frequently found structural motif in important biologically active molecules.
- Roiser, Lukas,Waser, Mario
-
supporting information
p. 2338 - 2341
(2017/05/12)
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- Direct access to α,α′-diarylated ketones through N-heterocyclic carbene-catalyzed 1,6-addition of aromatic aldehydes to para-quinone methides
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N-Heterocyclic carbene-catalyzed 1,6-addition of aromatic aldehydes to para-quinone methides has been developed. This method could efficiently furnish α,α′-diarylated ketones with good to high yields, which contain various functional groups.
- Zhang, Guifu,Jiang, Longxiang,Shi, Wenjuan,Zhou, Meiling,Qiu, Fenghao,Sun, Shaofa,Wang, Jian,Guo, Haibing
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supporting information
p. 803 - 810
(2017/04/06)
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- Tf 2 NH-Catalyzed 1,6-Conjugate Addition of Vinyl Azides with p -Quinone Methides: A Mild and Efficient Method for the Synthesis of β-Bis-Arylamides
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Tf 2 NH-catalyzed tandem 1,6-conjugate addition/Schmidt type rearrangement using vinyl azides and p -quinone methides to access a variety of β-bis-arylated amides is reported. The method is quick, efficient, mild, and high yielding with broad substrate scope.
- Rathod, Jayant,Sharma, Brijesh M.,Mali, Pramod S.,Kumar, Pradeep
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supporting information
p. 5224 - 5230
(2017/10/06)
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- Palladium-catalyzed Oxa-[4+2] Annulation of para-Quinone Methides
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A palladium-catalyzed oxa-[4+2] annulation of para-quinone methides with allyl carbonates bearing a nucleophilic alcohol side chain has been developed. This method provided an efficient strategy to the construction of 2-oxaspiro-cyclohexadienones via 1,6-conjugated addition-mediated allylation in moderate to good yields. Preliminary results on asymmetric derivatives promised potential in the synthesis of enantioenriched frameworks. (Figure presented.).
- Yuan, Zhenbo,Pan, Rui,Zhang, He,Liu, Lina,Lin, Aijun,Yao, Hequan
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supporting information
p. 4244 - 4249
(2017/12/18)
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- One-pot synthesis method for 4-aryl methylene-2,6-disubstituted-2,5-cyclohexadiene-1-one
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The invention discloses a one-pot synthesis process for 4-aryl methylene-2,6-disubstituted-2,5-cyclohexadiene-1-one. The process comprises the following steps: using 2,6-disubstituted phenol and benzaldehyde as initial raw materials; in the presence of a solvent, adding secondary amine and carrying out reaction to generate Mannich base; and then adding anhydride to obtain the product 4-aryl methylene-2,6-disubstituted-2,5-cyclohexadiene-1-one. By adopting the method disclosed by the invention, the 4-aryl methylene-2,6-disubstituted-2,5-cyclohexadiene-1-one can be prepared under normal conditions, intermediates do not need to be separated and purified, the operation is safe, the energy resources are saved, and the process is suitable for large-scale production.
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Paragraph 0055; 0056; 0057; 0058
(2016/10/10)
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- Organocatalyzed asymmetric 1,6-conjugate addition of para-quinone methides with dicyanoolefins
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A chiral thiourea catalyzed asymmetric 1,6-conjugate addition of para-quinone methides with dicyanoolefins has been developed. The reaction provided an efficient approach to the synthesis of chiral diarylmethine skeletons in good yields (up to 99% yield) with high diastereo- and enantioselectivity (>20:1 dr and up to 99.5:0.5 er), also on a gram scale. The preliminary mechanistic study showed that the remote stereocontrol was achieved through intermolecular hydrogen-bond interaction between the chiral thiourea catalyst and the para-quinone methides directly for the first time.
- Li, Xuanyi,Xu, Xiuyan,Wei, Weiwei,Lin, Aijun,Yao, Hequan
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supporting information
p. 428 - 431
(2016/02/19)
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- Bifunctional tertiary amine-squaramide catalyzed asymmetric catalytic 1,6-conjugate addition/aromatization of para-quinone methides with oxindoles
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The asymmetric catalytic 1,6-addition of p-QMs with racemic oxindoles under the bifunctional catalysis of C2-symmetric dimeric Cinchona-derived squaramide is described. This tertiary amine-squaramide catalyzed reaction provides a diastereoselective and enantioselective approach to the effective assembly of diverse diarylmethine-substituted oxindoles having vicinal tertiary and quaternary stereocenters.
- Deng, Yu-Hua,Zhang, Xiang-Zhi,Yu, Ke-Yin,Yan, Xu,Du, Ji-Yuan,Huang, Hanmin,Fan, Chun-An
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supporting information
p. 4183 - 4186
(2016/03/19)
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- 1,6-Addition Arylation of para-Quinone Methides: An Approach to Unsymmetrical Triarylmethanes
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A 1,6-addition arylation reaction of para-quinone methides with α-isocyanoacetamides and electron-rich aromatic compounds under metal-free conditions has been developed. BF3·Et2O plays two roles in the reaction: catalyzing the cyclization of α-isocyanoacetamides to give oxazoles, and activating the para-quinone methides to achieve the 1,6-addition arylation process. The reaction shows good functional group tolerance, scalability, and regioselectivity. It is a consice protocol for the synthesis of diverse unsymmetrical triarylmethanes. Further transformation of the resulting triarylmethanes provides an efficient route to some functionalized molecules.
- Gao, Shang,Xu, Xiuyan,Yuan, Zhenbo,Zhou, Haipin,Yao, Hequan,Lin, Aijun
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supporting information
p. 3006 - 3012
(2016/07/11)
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- Bifunctional Organo/Metal Cooperatively Catalyzed [3 + 2] Annulation of para-Quinone Methides with Vinylcyclopropanes: Approach to Spiro[4.5]deca-6,9-diene-8-ones
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A novel [3 + 2] annulation between para-quinone methides and vinylcyclopropanes for the synthesis of spiro[4.5]deca-6,9-diene-8-ones has been described. The palladium and phosphine-thiourea cooperative catalysis system played an important role in high yields and diastereoselectivities. The reaction exhibited good functional group tolerance and scalability.
- Yuan, Zhenbo,Wei, Weiwei,Lin, Aijun,Yao, Hequan
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supporting information
p. 3370 - 3373
(2016/07/26)
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- Expedient Access to Unsymmetrical Diarylindolylmethanes through Palladium-Catalyzed Domino Electrophilic Cyclization-Extended Conjugate Addition Approach
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A palladium-catalyzed domino process to access unsymmetrical diarylindolylmethanes has been developed through the annulation of o-alkynylanilines followed by 1,6-conjugate addition with p-quinone methides (p-QMs) under relatively mild conditions. The broad substrate scope of this methodology was demonstrated through the use of a wide range of substituted o-alkynylanilines and p-quinone methides, and in most cases, the unsymmetrical diarylindolylmethanes could be prepared in moderate to excellent yields. Notably, this method does not require any amino group protection. Moreover, 100% atom economy makes this transformation attractive from a green chemistry perspective.
- Reddy, Virsinha,Vijaya Anand, Ramasamy
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supporting information
p. 3390 - 3393
(2015/07/28)
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- Copper-Catalyzed Enantioselective 1,6-Boration of para-Quinone Methides and Efficient Transformation of gem-Diarylmethine Boronates to Triarylmethanes
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Presented is the first enantioselective copper-catalyzed 1,6-conjugate addition of bis(pinacolato)diboron to para-quinone methides. The reaction proceeds with excellent yields and good to excellent enantioselectivities, and provides an attractive approach to the construction of optically active gem-diarylmehtine boronic esters. Additionally, the subsequent conversion of the derived potassium trifluoroborates into triarylmethanes with highly enantiospecificity was realized.
- Lou, Yazhou,Cao, Peng,Jia, Tao,Zhang, Yongling,Wang, Min,Liao, Jian
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supporting information
p. 12134 - 12138
(2015/10/12)
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- Synthesis of spiro[2.5]octa-4,7-dien-6-one with consecutive quaternary centers via 1,6-conjugate addition induced dearomatization of para-quinone methides
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An efficient one-pot approach for the synthesis of spiro[2.5]octa-4,7-dien-6-ones by employing para-quinone methides has been developed. The reaction proceeded smoothly in high yields under mild conditions without the use of metals. Moreover, all products obtained herein contained two or three consecutive quaternary centers.
- Gai, Kuo,Fang, Xinxin,Li, Xuanyi,Xu, Jinyi,Wu, Xiaoming,Lin, Aijun,Yao, Hequan
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supporting information
p. 15831 - 15834
(2015/11/10)
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- 1,6-Conjugated Addition-Mediated [2+1] Annulation: Approach to Spiro[2.5]octa-4,7-dien-6-one
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A formal 1,6-conjugated addition-mediated [2+1] annulation to synthesize spiro[2.5]octa-4,7-dien-6-one with p-quinone methides and sulfur ylides has been described. This domino-type process was highly diastereoselective and exhibited good functional group tolerance and scalability without the use of metals and bases.
- Yuan, Zhenbo,Fang, Xinxin,Li, Xuanyi,Wu, Jie,Yao, Hequan,Lin, Aijun
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p. 11123 - 11130
(2015/11/18)
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- Copper-catalyzed silylation of p-quinone methides: New entry to dibenzylic silanes
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An efficient and general copper(i)-catalyzed silylation of p-quinone-methides is described. Non-symmetric dibenzylic silanes are obtained in high yields under mild reaction conditions. These compounds can be used as bench-stable benzylic carbanion precursors.
- López, Aurora,Parra, Alejandro,Jarava-Barrera, Carlos,Tortosa, Mariola
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supporting information
p. 17684 - 17687
(2015/12/18)
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- PROCESS FOR THE PRODUCTION OF QUINONE METHIDE
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This invention relates to a process for the production of quinone methods and more particularly to a method for process which optimizes the production of quinone methide, in particular 4-Benzylidene-2,6-di-tert-butyl-cyclohexa-2,5-dienone, while limiting the production of by products or waste.
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Page/Page column 2
(2008/12/05)
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- POLYMERIZATION INHIBITOR FOR AROMATIC VINYL COMPOUNDS AND METHOD FOR INHIBITING THE POLYMERIZATION OF THE COMPOUNDS
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According to the present invention, there are provided a polymerization inhibitor which is easy to handle and which has a little toxicity and a high polymerization-inhibitory effect toward an aromatic vinyl compound and a process for inhibiting the polymerization of the aromatic vinyl compound. The present invention relates to a polymerization inhibitor for the aromatic vinyl compound which comprises contain two ingredients of a specific quinone methide compound and a specific organic sulfonic acid compound, and to a process for inhibiting polymerization of the aromatic vinyl compound which comprises adding a specific quinone methide compound and a specific organic sulfonic acid compound simultaneously or further a specific quinone methide compound, a specific organic sulfonic acid compound and a specific N-oxyl compound simultaneously in the stage of producing, purifying, storing or transporting the aromatic vinyl compound.
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Page/Page column 6
(2008/06/13)
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- Inhibition of unsaturated monomers with 7-aryl quinone methides
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Ethylenically unsaturated monomers are protected from premature polymerization during manufacture and storage by the incorporation therein of an effective stabilizing amount of a 7-aryl quinone methide compound.
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- A new one-pot process for the preparation of 7-aryl-2,6-disubstituted quinone methides
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The instant invention pertains to a new one-pot process for the facile preparation of 7-aryl-2,6-disubstituted quinone methides of formula I where R1and R2are independently alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms or phenylalkyl of 7 to 15 carbon atoms, and R3is 2-, 3- or 4-pyridyl, 2- or 3-thienyl, 2- or 3-pyrryl, 2- or 3-furyl, aryl of 6 to 10 carbon atoms, or said aryl substituted by one to three alkyl of 1 to 8 carbon atoms, alkoxy of 1 to 8 carbon atoms, alkylthio of 1 to 8 carbon atoms, alkylamino of 1 to 8 carbon atoms, dialkylamino of 2 to 8 carbon atoms, alkoxycarbonyl of 2 to 8 carbon atoms, hydroxy, nitro, amino, cyano, carboxy, aminocarbonyl, chloro or mixtures of said substituents,which are useful as polymerization inhibitors for vinyl aromatic and acrylic monomers.
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- 7-substituted quinone methides as inhibitors for unsaturated monomers
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Ethylenically unsaturated monomers are protected from premature polymerization during manufacture and storage by the incorporation therein of an effective stabilizing amount of a 7-substituted quinone methide compound.
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- Electroorganic Reactions. 31. Quinonemethide Radical-Anions and Dianoins: Their Cathodic Generation and Reactivity
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The cathodic reactions of a number of relatively stable quinonemethides have been examined in detail by cyclic voltammetry, controlled potential coulometry, and rigorous product analysis following preparative-scale electrolyses.The results of cyclic voltammetric experiments differ in some respects from those of earlier polarographic work.The lifetimes of the electrogenerated radical-anions and dianions, in the absence of added electrophile, are governed by steric hindrance.Hindered intermediates are relatively long-lived yet hydrogenate in the presence of proton donor and alkylate in the presence of methyl iodide.Less hindered analogue efficiently and rapidly dimerize, at carbon, with concomitant protonation or O-methylation depending on added electrophile.The ambident cathodically generated nucleophiles alkylate at both carbon and oxygen, and the competition is crucially dependent on the cation (Bu4N+ or Li+).Fuchsone 3 gives reduction products which vary with initial concentration and on the presence, or otherwise, of oxygen.Efficient reaction between oxygen and triarylmethyl radicals generated, e.g., from 3 has been demonstrated.
- Goulart, Marilia O. F.,Utley, James H. P.
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p. 2520 - 2525
(2007/10/02)
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