- Dramatic influence of ester steric hindrance on the diastereoselectivity of a Michael addition towards the synthesis of the ABC tricycle of hexacyclinic acid
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During our studies toward the synthesis of the ABC ring system of hexacyclinic acid, we observed an unexpected influence of the steric bulk of the ester group of the Michael acceptor in a key conjugate addition. We propose an eight-membered ring transition state to explain the formation of the undesired diastereomer in the case of unhindered esters.
- Audic, Alexandre,Oriez, Rapha?l,Prunet, Jo?lle
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- Homologation of Electron-Rich Benzyl Bromide Derivatives via Diazo C-C Bond Insertion
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The ability to manipulate C-C bonds for selective chemical transformations is challenging and represents a growing area of research. Here, we report a formal insertion of diazo compounds into the "unactivated"C-C bond of benzyl bromide derivatives catalyzed by a simple Lewis acid. The homologation reaction proceeds via the intermediacy of a phenonium ion, and the products contain benzylic quaternary centers and an alkyl bromide amenable to further derivatization. Computational analysis provides critical insight into the reaction mechanism, in particular the key selectivity-determining step.
- Modak, Atanu,Alegre-Requena, Juan V.,De Lescure, Louis,Rynders, Kathryn J.,Paton, Robert S.,Race, Nicholas J.
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supporting information
p. 86 - 92
(2021/12/27)
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- Erratum: Oxazaborolidinium Ion-Catalyzed Cyclopropanation of α-Substituted Acroleins: Enantioselective Synthesis of Cyclopropanes Bearing Two Chiral Quaternary Centers (J. Am. Chem. Soc. (2011) 133:51 (20708?20711) DOI: 10.1021/ja209270e)
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Pages 20709 and 20710. In the published version of the paper, the trans:cis ratios of 2w and 2x were reversed. The revised results were confirmed by NOE experiments and comparison of the optical rotation data with reported values after transformation. The
- Gao, Lizhu,Hwang, Geum-Sook,Ryu, Do Hyun
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supporting information
p. 6021 - 6022
(2021/05/13)
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- Catalytic Ring Expansion of Activated Heteroarenes Enabled by Regioselective Dearomatization
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Catalytic ring expansion of activated heteroarenes through 1,4-dearomative addition of diazoacetates was established for the construction of various fused azepines by an elaborate control of the reaction kinetics at each step. The use of a silver catalyst was essential to drive the overall reaction for generating the desired seven-membered azepines. Because of the excellent substrate scope and selectivity, the developed methodology presents an innovative approach for the synthesis of multifused azepines, which are biologically relevant molecules.
- Kim, Jiyoung,Yoo, Eun Jeong
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supporting information
p. 4256 - 4260
(2021/06/28)
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- Tridentate Nickel(II)-Catalyzed Chemodivergent C-H Functionalization and Cyclopropanation: Regioselective and Diastereoselective Access to Substituted Aromatic Heterocycles
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A Schiff-base nickel(II)-phosphene-catalyzed chemodivergent C-H functionalization and cyclopropanation of aromatic heterocycles is reported in moderate to excellent yields and very good regioselectivity and diastereoselectivity. The weak, noncovalent interaction between the phosphene ligand and Ni center facilitates the ligand dissociation, generating the electronically and coordinatively unsaturated active catalyst. The proposed mechanisms for the reported reactions are in good accord with the experimental results and theoretical calculations, providing a suitable model of stereocontrol for the cyclopropanation reaction.
- Nag, Ekta,Gorantla, Sai Manoj N. V. T.,Arumugam, Selvakumar,Kulkarni, Aditya,Mondal, Kartik Chandra,Roy, Sudipta
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supporting information
p. 6313 - 6318
(2020/09/02)
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- Synthesis of spiro[2,3-dihydrofuran-3,3′-oxindole] derivatives: Via a multi-component cascade reaction of α-diazo esters, water, isatins and malononitrile/ethyl cyanoacetate
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We report a green synthesis of spiro[2,3-dihydrofuran-3,3′-oxindole] derivatives which are of potential value in medicinal chemistry. We are able to access spiro[2,3-dihydrofuran-3,3′-oxindole] derivatives via a Cu(OTf)2-catalyzed or Cu(OTf)2/Rh2(OAc)4-cocatalyzed multi-component cascade reaction of α-diazo esters, water, isatins and malononitrile/ethyl cyanoacetate. The reaction can be accomplished in good to excellent yields (60-99%), and the structure of products 6a and 6k was supported by X-ray crystallography. The catalyst Cu(OTf)2 can be recycled 4 times without a sharp loss of the yield of 6a. 6q can be easily synthesized in gram scale. In brief, the reaction is characterized by step economy, a harmless solvent, and a recyclable catalyst.
- Shi, Taoda,Teng, Shenghan,Wei, Yajie,Guo, Xin,Hu, Wenhao
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supporting information
p. 4936 - 4940
(2019/09/30)
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- A General Catalytic Route to Enantioenriched Isoindolinones and Phthalides: Application in the Synthesis of (S)-PD 172938
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Chiral Br?nsted acid catalyzed enantioselective syntheses of isoindolinones and phthalides have been accomplished via tandem Mannich-lactamization and aldol-lactonization reactions, respectively. A variety of enantioenriched isoindolinones (up to 99% ee) and phthalides (up to 85% ee) containing α-diazoesters were afforded in excellent yields. Furthermore, a concise synthesis of (S)-PD 172938 has been demonstrated by using this protocol.
- Ray, Sumit K.,Sadhu, Milon M.,Biswas, Rayhan G.,Unhale, Rajshekhar A.,Singh, Vinod K.
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supporting information
(2019/01/21)
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- A General Catalytic Route to Enantioenriched Isoindolinones and Phthalides: Application in the Synthesis of (S)-PD 172938
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Chiral Br?nsted acid catalyzed enantioselective syntheses of isoindolinones and phthalides have been accomplished via tandem Mannich-lactamization and aldol-lactonization reactions, respectively. A variety of enantioenriched isoindolinones (up to 99% ee) and phthalides (up to 85% ee) containing α-diazoesters were afforded in excellent yields. Furthermore, a concise synthesis of (S)-PD 172938 has been demonstrated by using this protocol.
- Ray, Sumit K.,Sadhu, Milon M.,Biswas, Rayhan G.,Unhale, Rajshekhar A.,Singh, Vinod K.
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supporting information
p. 417 - 422
(2019/01/23)
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- In situ generation of nitrile oxides from copper carbene and tert -butyl nitrite: Synthesis of fully substituted isoxazoles
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Herein, we present a novel [3 + 2] cycloaddition reaction of β-keto esters with nitrile oxides, which were generated in situ from copper carbene and tert-butyl nitrite. This three-component reaction provides new methodology for the direct synthesis of fully substituted isoxazole derivatives, featuring mild reaction conditions, readily accessible starting materials and simple operation. The experimental studies and DFT calculations suggest that the reaction starts with the generation of the key intermediate nitrile oxides, followed by a [3 + 2] cycloaddition reaction of β-keto esters to give the final isoxazole products.
- Chen, Rongxiang,Ogunlana, Abosede Adejoke,Fang, Shangwen,Long, Wenhao,Sun, Hongmei,Bao, Xiaoguang,Wan, Xiaobing
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supporting information
p. 4683 - 4687
(2018/07/06)
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- In Situ Generation of Oxazole Ylide and Interception with Sulfonamide: Construction of Amidines Using Two Diazo Molecules
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A novel generation of oxazole ylide and interception with sulfonamide have been well developed to construct fully substituted amidines. This copper-catalyzed four-component reaction incorporates two diazo molecules to target amidines and shows broad substrate scope, excellent functional groups tolerance and good to excellent yields.
- Chen, Jijun,Long, Wenhao,Zhao, Yanwei,Li, Haiyan,Zheng, Yonggao,Lian, Pengcheng,Wan, Xiaobing
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supporting information
p. 857 - 865
(2018/07/31)
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- Interception of Radicals by Molecular Oxygen and Diazo Compounds: Direct Synthesis of Oxalate Esters Using Visible-Light Catalysis
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The synthesis of oxalate esters through a radical process, rather than the traditional ionic reaction, has been well developed in which the radicals induced by visible light are trapped by molecular oxygen and diazo compounds under room temperature. This reaction is operationally simple, mild, and shows broad substrate scopes in α-bromo ketones and diazo compounds.
- Ma, Meihua,Hao, Weiwei,Ma, Liang,Zheng, Yonggao,Lian, Pengcheng,Wan, Xiaobing
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supporting information
p. 5799 - 5802
(2018/09/12)
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- A chiral Br?nsted acid-catalyzed highly enantioselective Mannich-type reaction of α-diazo esters with in situ generated N -acyl ketimines
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A chiral phosphoric acid-catalyzed asymmetric Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines, derived from 3-hydroxyisoindolinones has been demonstrated in this communication. A variety of isoindolinone-based α-amino diazo esters bearing a quaternary stereogenic center were afforded in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee). Furthermore, the synthetic utility of the products has been depicted by the hydrogenation of the diazo moiety of adducts.
- Unhale, Rajshekhar A.,Sadhu, Milon M.,Ray, Sumit K.,Biswas, Rayhan G.,Singh, Vinod K.
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supporting information
p. 3516 - 3519
(2018/04/10)
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- In Situ Generation of Quinolinium Ylides from Diazo Compounds: Copper-Catalyzed Synthesis of Indolizine
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The Cu-catalyzed three-component reaction between quinolines, diazo compounds, and alkenes has been established for direct construction of indolizine derivatives via quinolinium ylides. This methodology is distinguished by the use of a commercially inexpensive catalyst and readily available starting materials, wide substrate scope, and operational simplicity.
- Chen, Rongxiang,Zhao, Yanwei,Sun, Hongmei,Shao, Ying,Xu, Yudong,Ma, Meihua,Ma, Liang,Wan, Xiaobing
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p. 9291 - 9304
(2017/09/22)
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- Construction of enantiomerically enriched diazo compounds using diazo esters as nucleophiles: Chiral Lewis base catalysis
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Amazing diazo: The title reaction leads to highly functionalized diazo compounds in good yields with excellent enantioselectivities (see scheme; Boc=tert-butoxycarbonyl). The utility of the products was demonstrated by the rapid synthesis of a number of o
- Mao, Haibin,Lin, Aijun,Shi, Yan,Mao, Zhijie,Zhu, Xuebin,Li, Weipeng,Hu, Hongwen,Cheng, Yixiang,Zhu, Chengjian
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supporting information
p. 6288 - 6292
(2013/07/05)
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- A simple criterion for gas chromatography/mass spectrometric analysis of thermally unstable compounds, and reassessment of the by-products of alkyl diazoacetate synthesis
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Rationale: A principal limitation of gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) is the thermal instability of analytes. We propose that the injector and column temperatures should not exceed the atmospheric pressure boiling point, without decomposition, of the highest homologue of the series being analyzed, instead of the time-consuming procedure of obtaining chromatograms using different temperatures. Methods: A series of thermally unstable diazocarbonyl compounds, alkyl diazoacetates (predicted limit of stability approx. 140 °C, the boiling point of ethyl diazoacetate), was selected for GC/MS analysis using standard equipment. Different GC separation conditions were selected so that the retention temperatures of target compounds were both below and above 140°C. Results: Analyzing alkyl diazoacetates within their thermal stability range permitted reanalysis of their typical synthesis by-products. No dialkyl fumarate or maleate impurities, principal decomposition products which have often been reported previously, were found. Instead, alkyl esters of glycolic acid nitrate, O2NOCH 2CO2R, and 'pseudo-dimeric' products, ROCO[C 2H3NO]CO2R, were discovered for the first time. Conclusions: Avoiding the decomposition of thermally unstable organic compounds during GC and/or GC/MS analysis requires estimating their degradation temperature limits. This limit can be estimated as being equal to the atmospheric pressure boiling point of the highest homologue in the homologous series under consideration that does not decompose on boiling. Copyright
- Kornilova, Tatiana A.,Ukolov, Anton I.,Kostikov, Rafael R.,Zenkevich, Igor G.
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p. 461 - 466
(2013/03/14)
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- CONTINUOUS FLOW PROCESS FOR THE PRODUCTION OF DIAZO ESTERS
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Processes for producing diazo ester derivatives in a single phase system in a continuous flow reactor.
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Page/Page column 32
(2012/10/08)
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- Stability of diazocarbonyl compounds under the conditions of gas chromatography and chromatography-mass spectrometry analysis
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The gas chromatographic analysis of alkyldiazoacetates N 2CHCO2R (R = CH3 - C4H9), α-aliphatic diazoketones RCOCHN2 (R = C3H 7, C5H11, and C9H19), and aryl-substituted diazoketones Ph (CH2)nCOCHN2 (n = 0-2) is shown to be possible when their retention temperatures are below the boiling points of compounds of this series at atmospheric pressure without decomposition (about 140°C). At higher temperatures occurs partial or complete decomposition of α-diazoketones in chromatographic columns to form ketenes. Among the impurities in the reaction mixtures at the diazotization of corresponding alkyl glycinates were identified for the first time the nitrate esters of glycolic acid O2NOCH2CO2R, as well as the dimeric products. All diazocarbonyl compounds and the impurities were characterized by mass spectra. For the first time their gas chromatographic retention indices were determined. Pleiades Publishing, Ltd., 2012.
- Kornilova,Ukolov,Kostikov,Zenkevich
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p. 1675 - 1685
(2013/02/23)
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- Copper-promoted cycloaddition of diazocarbonyl compounds and acetylides
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(Chemical Equation Presented) HOMO-logous: The copper-mediated cycloaddition of alkynes with diazo carbonyl compounds to give pyrazoles is reminiscent of the copper-catalyzed cycloaddition of alkynes and azides. The formation of the copper acetylide is proposed to narrow the energy gap between the highest occupied molecular orbital (HOMO) of the alkyne and the lowest unoccupied molecular orbital (LUMO) of the diazo compound.
- Qi, Xiangbing,Ready, Joseph M.
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p. 3242 - 3244
(2008/02/13)
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- Highly chemo- and stereoselective intermolecular coupling of diazoacetates to give cis-olefins by using Grubbs second-generation catalyst
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Highly stereoselective formation of cis-2-ene-1,4-diesters by homo- and heterocoupling of α-diazoacetates in the presence of Grubbs second-generation catalyst is demonstrated. The dual reactivity of the catalyst in alkene metathesis and diazocoupling has been exploited in the synthesis of 12-26-membered macrocyclic dienyl dilactones by one-pot carbene dimerisation/ring-closing metathesis.
- Hodgson, David M.,Angrish, Deepshikha
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p. 3470 - 3479
(2008/02/08)
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- Synthesis of α-diazo-β-hydroxyesters through a one-pot protocol by phase-transfer catalysis: Application to enantioselective aldol-type reaction and diastereoselective synthesis of α-amino-β-hydroxyester derivatives
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The one-pot synthesis of α-diazo-β-hydroxyesters from sodium azide under phase-transfer-catalyzed conditions has been achieved. This protocol includes three different chemical transformations promoted by a single catalyst in each step to give products in good to excellent yields. The reaction was applied to a catalytic asymmetric aldol-type reaction using α-diazoesters with aldehydes in the presence of a chiral quaternary ammonium salt and gave products with up to 81% ee. The diastereoselective transformation of the products to chiral α-amino-β-hydroxyester derivatives is also described.
- Hasegawa, Kazuya,Arai, Shigeru,Nishida, Atsushi
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p. 1390 - 1401
(2007/10/03)
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- Multi-substituted fullerenes and methods for their preparation and characterization
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The invention is directed to multiply-substituted fullerene derivatives of novel configurations, and methods for their preparation and use. The methods involve the combinatorial synthesis of a library of fullerene derivatives and comprises the steps of fo
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- NITROCYCLOPROPANES FROM NITRODIAZOMETHANES. PREPARATION AND REACTIVITY
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Nitrodiazo compounds cyclopropanate electron rich alkenes in the presence of rhodium(II) acetate.The yields and diastereoselectivities are dependent on both the alkene and the nitrodiazo precursor.Nitrocyclopropanecarboxylates undergo ring opening, reduct
- O'Bannon, P. E.,Dailey, William P.
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p. 7341 - 7358
(2007/10/02)
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