- Bio-inspired asymmetric aldehyde arylations catalyzed by rhodium-cyclodextrin self-inclusion complexes
-
Transition-metal catalysts are powerful tools for carbon-carbon bond-forming reactions that are difficult to achieve using native enzymes. Enzymes that exhibit inherent selectivities and reactivities through host-guest interactions have inspired widesprea
- Asahi, Kaoru,Fujiwara, Shin-Ichi,Iwasaki, Takanori,Kambe, Nobuaki,Takahashi, Ryota,Tsuda, Susumu,Ueda, Ryoji,Yamauchi, Hiroki
-
supporting information
p. 801 - 807
(2022/02/03)
-
- Asymmetric Transfer Hydrogenation of Aryl Heteroaryl Ketones using Noyori-Ikariya Catalysts
-
A range of ketones flanked by a combination of an aromatic and a heterocyclic ring (furan, thiophene, N-methylimidazole) were reduced under asymmetric transfer hydrogenation (ATH) conditions. Using a range of [(arene)Ru(TsDPEN)Cl] precatalysts, including tethered derivatives, the reduction enantioselectivity was high (up to 99 % ee) in cases where the aromatic ring contained an ortho-substituent. The enantioselectivity is influenced by a combination of steric and electronic factors which for the furan and thiophene series, follow literature precedents. In the case of the N-methylimidazole-containing ketones, an unexpected switch in enantioselectivity took place upon variation of the opposing aromatic group. Pyrrole- containing ketones were resistant to reduction. This study demonstrates the asymmetric transfer hydrogenation (ATH) of a range of hindered heterocyclic ketones, in high conversion and ee, using Noyori-Ikariya catalysts.
- Zheng, Ye,Martinez-Acosta, Jaime A.,Khimji, Mohammed,Barbosa, Luiz C. A.,Clarkson, Guy J.,Wills, Martin
-
p. 4384 - 4391
(2021/08/23)
-
- Isomerization of Propargyl Ethers of 2-Hydroxyoxiranes to Furan Derivatives on Silver Catalysts
-
Abstract: It was shown that propargyl ethers of 2-hydroxyoxiranes in the presence of asilver salt of a molybdenum heteropoly acid as a catalyst leads to the formationof furan derivatives with a yield of up to 62.3% and highregioselectivity. [Figure not available: see fulltext.]
- Talybov, G. M.
-
p. 1153 - 1156
(2021/08/06)
-
- Development of Chiral C2-Symmetric N-Heterocyclic Carbene Rh(I) Catalysts through Control of Their Steric Properties
-
Chiral square-planar Rh(I) complexes based on new C2-symmetric NHC ligands have been synthesized selectively in a few steps as single diastereoisomers. These chiral precatalysts were applied to the asymmetric transfer hydrogenation of 1-phenylp
- Abadie, Marc-Antoine,Macintyre, Kirsty,Boulho, Cédric,Hoggan, Peter,Capet, Frédéric,Agbossou-Niedercorn, Francine,Michon, Christophe
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p. 536 - 543
(2019/01/14)
-
- Nickel Catalyzed Intermolecular Carbonyl Addition of Aryl Halide
-
In this study, we develop a nickel-catalyzed carbonyl arylation reaction employing aldehydes with aryl and allyl halides. Various aryl, α,β-unsaturated aldehyde and aliphatic aldehydes can be converted into their corresponding secondary alcohols in moderate-to-high yields. In addition, we extended this approach to develop an asymmetric reductive coupling reaction that combines nickel salts with chiral bisoxazoline ligands to give secondary alcohols with moderate enantioselectivity.
- Ishida, Seima,Suzuki, Hiroyuki,Uchida, Seiichiro,Yamaguchi, Eiji,Itoh, Akichika
-
supporting information
p. 7483 - 7487
(2019/12/11)
-
- Divergent Synthesis of Dihydropyranone Stereoisomers via N-Heterocyclic Carbene Catalysis
-
We recently developed a novel chiral N-heterocyclic carbene (NHC) catalyzed dynamic kinetic enantioselective acylation (DKEA) and dynamic kinetic diastereoselective acylation (DKDA) of Achmatowicz rearrangement products to generate useful intermediates for the further synthesis of carbohydrates. In this update, we describe a divergent NHC catalytic strategy for the stereoselective preparation of all four isomers starting from a common racemic precursor. The present report provides easy access to diverse optically pure dihydropyranones. (Figure presented.).
- Zhao, Changgui,Wang, Jian
-
supporting information
p. 1668 - 1672
(2019/02/19)
-
- Chloroperoxidase-Catalyzed Achmatowicz Rearrangements
-
Chloroperoxidase from Caldariomyces fumago catalyzes the selective oxidation of furfuryl alcohols in an Achmatowicz-type ring expansion. In combination with glucose oxidase as oxygen-activating biocatalyst, a purely enzymatic, aerobic protocol for the synthesis of 6-hydroxypyranone building blocks is obtained. Thanks to an only modest stereochemical bias of the oxygenating heme protein, optically active alcohols of either configuration are converted without a significant mismatch opening up opportunities for enantioselective multienzymatic cascades. Balancing the oxidase-driven aerobic activation, extended enzyme half-lives and productive conversion of poorly soluble and slowly reacting substrates can be achieved with high yields of the six-membered O-heterocycles.
- Thiel, Daniel,Blume, Fabian,J?ger, Christina,Deska, Jan
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p. 2717 - 2725
(2018/05/14)
-
- Scandium as a pre-catalyst for the deoxygenative allylation of benzylic alcohols
-
Scandium triflate is an effective pre-catalyst for the deoxygenative allylation of benzylic alcohols with a narrow substrate window. The reaction is shown to proceed through a "hidden Br?nsted acid" mechanism. The reaction is efficient provided that the aryl group is neither too electron rich nor too electron poor. It is shown that this allows useful selectivity. The reaction also works for benzyhydryl alcohols with broader scope. The reaction may also be catalysed by Nafion.
- ?oli?, Ivan,Seankongsuk, Pattarakiat,Loh, Joanna Kejun,Vilaivan, Tirayut,Bates, Roderick W.
-
supporting information
p. 119 - 123
(2017/12/27)
-
- The inexpensive additive N-methylmorpholine effectively decreases the equivalents of nucleophiles in the catalytic highly enantioselective arylation of aryl aldehydes
-
Highly enantioselective arylation of aryl aldehydes catalyzed by (S)-H8-BINOL-Ti(Oi-Pr)2 complex in the presence of N-methylmorpholine (NMM) as an effective and inexpensive additive is described for the first time. We found high enan
- Wang, Pei,Liu, Yue,Zhang, Ya-Lun,Da, Chao-Shan
-
supporting information
p. 443 - 450
(2017/07/25)
-
- Visible-light-mediated achmatowicz rearrangement
-
Visible-light-mediated photoredox catalysis is a viable method to access highly reactive intermediates from cheap, readily available, and shelfstable reagents to perform clean chemical transformations. Here, we report the first photoredox-catalyzed Achmatowicz reaction of furfuryl alcohol derivatives to produce functionalized dihydropyranones while only forming easily separable NaHSO4 as a byproduct. The water solubility of the byproduct facilitates direct Boc-protection of the resulting hemiacetal without the need for column purification. The reaction is very robust and permits the use of various aqueous solutions and light sources including sunlight.
- Plutschack, Matthew B.,Seeberger, Peter H.,Gilmore, Kerry
-
supporting information
p. 30 - 33
(2017/11/28)
-
- Newly synthesized furanoside-based NHC ligands for the arylation of aldehydes
-
New furanoside-based NHC precursor salts (2) were synthesized using amino alcohols from the chloralose derivatives of glucose (a), galactose (b), and mannose (c). The novel compounds were fully characterized by 1H NMR, 13C NMR, and elemental analyses. The catalytic activities of these salts were tested in the arylation of aldehydes as catalysts that were generated in situ from [RhCl(COD)]2. In addition, 2a was converted to the rhodium complex 3a in order to compare the results obtained in situ. The newly synthesized compounds were very efficient in terms of yield; nevertheless they did not exhibit a chiral induction.
- Denizalti, Serpil,?etin Telli, Fatma,Yildiran, Selin,Salman, Azize Ye?im,?etinkaya, Bekir
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p. 689 - 697
(2016/11/09)
-
- Synthesis of new benzimidazolium salts and their application in the asymmetric arylation of aldehydes
-
A series of novel chiral benzimidazolium salts, the precursor of N-heterocyclic carbene ligands, were designed and synthesized from 1,2-dibromobenzene. In situ prepared corresponding carbenes were tested in asymmetric Rh-catalyzed arylation of aromatic aldehydes, affording chiral diarylmethanols with high yields and moderate enantioselectivities.
- He, Wei-Ping,Zhou, Bi-Hui,Zhou, Ya-Li,Li, Xiang-Rong,Fan, Li-Mei,Shou, Hao-Wen,Li, Jie
-
supporting information
p. 3152 - 3155
(2016/07/06)
-
- Enantioselective addition of ArTi(OiPr)3 to aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol
-
Asymmetric additions of ArTi(OiPr)3 to aldehydes catalyzed by a titanium catalyst of N-sulfonylated amino alcohols were reported, and results showed that the chiral N-sulfonylated amino alcohol with two stereogenic centers could catalyze the asymmetric addition of ArTi(OiPr)3 to aldehydes to afford desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 95% ee.
- Chang, Shih-Ju,Zhou, Shuangliu,Gau, Han-Mou
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p. 9368 - 9373
(2015/02/19)
-
- Zn(salen)-catalyzed enantioselective phenyl transfer to aldehydes and ketones with organozinc reagent
-
Abstract A chiral zinc complex of salen was found to be an efficient catalyst for the phenyl transfer of organozinc reagent to aromatic aldehydes and ketones. High enantioselectivities were obtained in reactions of both aromatic aldehydes and ketones (up to 97% and 92% ee, respectively).
- Shimizu, Keisuke,Uetsu, Hidenori,Gotanda, Takashi,Ito, Katsuji
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p. 1238 - 1242
(2015/03/31)
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- NMO·TPB: A selectivity variation on the Ley-Griffith TPAP oxidation
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A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO·TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.
- Moore, Peter W.,Mirzayans, Paul M.,Williams, Craig M.
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p. 3567 - 3571
(2015/03/04)
-
- Iridium-Catalyzed Dynamic Kinetic Isomerization: Expedient Synthesis of Carbohydrates from Achmatowicz Rearrangement Products
-
A highly stereoselective dynamic kinetic isomerization of Achmatowicz rearrangement products was discovered. This new internal redox isomerization provided ready access to key intermediates for the enantio- and diastereoselective synthesis of a series of naturally occurring sugars. The nature of the de novo synthesis also enables the preparation of both enantiomers.
- Wang, Hao-Yuan,Yang, Ka,Bennett, Scott R.,Guo, Sheng-Rong,Tang, Weiping
-
supporting information
p. 8756 - 8759
(2015/11/27)
-
- Direct trifluoromethylthiolation of alcohols under mild reaction conditions: Conversion of R-OH into R-SCF3
-
A direct process for the trifluoromethylthiolation of allylic and benzylic alcohols under mild conditions has been developed. A wide range of free alcohols underwent nucleophilic substitution in the presence of stable CuSCF3 and BF3·Et2O to give the corresponding products in good to excellent yields.
- Nikolaienko, Pavlo,Pluta, Roman,Rueping, Magnus
-
supporting information
p. 9867 - 9870
(2014/08/18)
-
- Aryl bromides as inexpensive starting materials in the catalytic enantioselective arylation of aryl aldehydes: The additive TMEDA enhances the enantioselectivity
-
We used aryl bromides as inexpensive starting materials to enantioselectively arylate aldehydes in one pot. Aryl bromides readily transfer aryls to aryllithiums with n-butyllithium, successively to triarylaluminums with aluminum chloride, and then to aryltitaniums with titanium isopropoxide. Finally aryltitaniums arylate aldehydes catalyzed by (S)-H8-BINOL-Ti(Oi-Pr)2 in excellent yields and enantioselectivities. The additive TMEDA evidently suppresses the racemic background reaction promoted by LiCl generated from salt metathesis. This procedure represents a cost-effective and operationally convenient method for enantioenriched diarylmethanols.
- Yang, Yong-Xin,Liu, Yue,Zhang, Lei,Jia, Yan-E,Wang, Pei,Zhuo, Fang-Fang,An, Xian-Tao,Da, Chao-Shan
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p. 10696 - 10702
(2015/02/19)
-
- An expeditious asymmetric synthesis of the polyketide unit present in HIV-inhibitory depsipeptides aetheramide A and B
-
The enantioselective synthesis of the polyketide unit present in depsipeptides aetheramide A and B, which possess potent HIV-inhibitory activity, is accomplished from a chiral furyl carbinol.
- Revu, Omkar,Prasad, Kavirayani R.
-
p. 2887 - 2890
(2015/02/05)
-
- Development of new P-chiral P,π-dihydrobenzooxaphosphole hybrid ligands for asymmetric catalysis
-
A new family of P-chiral P,π-hybrid ligands was prepared from the dihydrobenzooxaphosphole core. These new ligands were demonstrated to be both sterically and electronically tunable at the substituents on the phosphorus atom and the π-system of the ligand. Application of these new ligands to the catalytic asymmetric addition of boronic acids to imine electrophiles was shown to proceed with high levels of enantioinduction. (Chemical Equation Presented).
- Sieber, Joshua D.,Chennamadhavuni, Divya,Fandrick, Keith R.,Qu, Bo,Han, Zhengxu S.,Savoie, Jolaine,Ma, Shengli,Samankumara, Lalith P.,Grinberg, Nelu,Lee, Heewon,Song, Jinhua J.,Senanayake, Chris H.
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p. 5494 - 5497
(2015/02/05)
-
- Bu4N+ alkoxide-initiated/autocatalytic addition reactions with organotrimethylsilanes
-
The use of Me3SiO-/Bu4N+ as a general activator of organotrimethylsilanes for addition reactions has been established. The broad scope of the method offers trimethylsilanes (including acetate, allyl, propargyl, benzyl, dithiane, heteroaryl, and aryl derivatives) as bench-stable organometallics that can be readily utilized as carbanion equivalents for synthesis. Reactions are achieved at rt without the requirement of specialized precautions that are commonplace for other organometallics.
- Das, Manas,O'Shea, Donal F.
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p. 5595 - 5607
(2014/07/08)
-
- Lewis base activation of Lewis acids: Group 13. in situ generation and reaction of borenium ions
-
A variety of Lewis bases were combined with 9-BBN-NTf2 to establish the requirements for the generation of borenium cations. Five different types of behaviors were found, but the most interesting was the combination of Et3N, DABCO, 2,6-lutidine, or Ph3P=S, which formed borenium ions exclusively even in sub- or superstoichiometric quantities. The 9-BBN borenium ion complex of 2,6-lutidine rapidly catalyzes the hydrosilylation of a variety of ketones in the presence of Et3SiH. Preliminary mechanistic experiments suggest that the reduction involves borenium ion activation of Et3SiH and not the ketone.
- Denmark, Scott E.,Ueki, Yusuke
-
supporting information
p. 6631 - 6634
(2014/01/06)
-
- Synthesis of novel planar chiral Ag and Rh N-heterocyclic carbene complexes derived from [2.2]paracyclophane and their application in ultrasound assisted asymmetric addition reactions of organoboronic acids to aldehydes
-
Three novel planar chiral N-heterocyclic carbene silver and rhodium complexes based on [2.2]paracyclophane have been prepared. These could be used as catalysts/precatalysts for the asymmetric 1,2-addition of organoboronic acids to aldehydes. We optimized the reaction conditions and have applied ultrasonic irradiation in the asymmetric arylation for the first time. Under ultrasound irradiation, the combination of planar chiral NHC-Ag complex 5 and RhCl 3 can achieve higher catalytic activities in the asymmetric addition of organoboronic acids to aldehydes.
- Duan, Wenzeng,Ma, Yudao,He, Fuyan,Zhao, Lei,Chen, Jianqiang,Song, Chun
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p. 241 - 248
(2013/04/24)
-
- A chiral ruthenium-monophosphine catalyst for asymmetric addition of arylboronic acids to aryl aldehydes
-
A novel ruthenium catalyst on the basis of a chiral monophosphorus ligand is efficient for the asymmetric addition of arylboronic acids to aryl aldehydes, providing a series of chiral diarylmethanols in excellent yields and enantioselectivities (up to 92% ee). Preliminary study has shown that this process is catalyzed by a Ru complex with a single monophosphorus ligand.
- Li, Ke,Hu, Naifu,Luo, Renshi,Yuan, Weicheng,Tang, Wenjun
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p. 6350 - 6355
(2013/07/26)
-
- PROCESS FOR PRODUCING OPTICALLY ACTIVE ALCOHOL
-
Disclosed is a method for producing an optically active alcohol including reacting a titanium compound, an aromatic magnesium compound and a carbonyl compound in the presence of an optically active biphenol compound having a predetermined structure and an ether compound having a predetermined structure.
- -
-
Page/Page column 23
(2012/02/14)
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- METHOD FOR SYNTHESIS OF SECONDARY ALCOHOLS
-
A method for synthesis of secondary alcohols is provided for pharmaceutical secondary alcohol by addition of organoboronic acids with aldehydes in presence of the cobalt ion and bidentate ligands as the catalyst. In addition, an enantioselective synthesis method for secondary alcohols is also herein provided in the present invention. The present invention has advantages in using less expensive cobalt ion and commercially available chiral ligands as the catalyst, wide scope of organoboronic acids and aldehydes compatible with this catalytic reaction and achieving excellent yields and/or enantiomeric excess.
- -
-
Page/Page column 2
(2012/06/16)
-
- Asymmetric additive-free aryl addition to aldehydes using perhydrobenzoxazines as ligands and boroxins as aryl source
-
A highly efficient enantioselective aryl addition to aldehydes using boroxins as aryl source and conformationally restricted perhydro-1,3- benzoxazines as ligands is reported. Both enantiomeric forms of chiral arylphenylmethanols and 1,1′-disubstituted diarylmethanols are afforded with excellent yields and enantioselectivities using the same ligand by means of an appropriate combination of boroxin and aromatic aldehyde. The enantiocontrol is not significantly influenced by electronic effects or steric hindrance, even with substituted boroxins. Very homogeneous ee's are reached when substituted arylboroxins are employed, without the use of any class of additive or pre-treatment.
- Infante, Rebeca,Nieto, Javier,Andres, Celia
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experimental part
p. 6691 - 6699
(2011/11/04)
-
- Structural influence of chiral tertiary aminonaphthol ligands on the asymmetric phenyl transfer to aromatic aldehydes
-
A series of chiral tertiary aminonaphthol ligands were prepared from 2-naphthol, (S)-1-phenylethylamine, and aldehydes with diverse substituted groups. The results of asymmetric phenyl transfer to aromatic aldehydes catalyzed by these chiral ligands indicated that enantioselectivities were greatly influenced by the electronic and steric effects of the ligands. Copyright
- Wei, Hui,Yin, Lu,Luo, Haibin,Li, Xingshu,Chan, Albert S. C.
-
experimental part
p. 222 - 227
(2012/03/27)
-
- Catalytic enantioselective alkylation and arylation of aldehydes by using grignard reagents
-
We have developed an efficient and practical method for the catalytic enantioselective alkylation and arylation of aldehydes by using Grignard reagents in combination with titanium tetraisopropoxide. Grignard reagents and titanium tetraisopropoxide are mixed in a molar ratio of ca. 1:2. In the presence of catalyst (24mol%), which is formed in situ from a BINOL ligand 4a and 4b and titanium tetraisopropoxide, the resulting mixed titanium reagents undergo addition to aldehydes with high enantioselectivities (typically >90% ee) and high yields. The method is applicable to various combination of aldehydes (R1CHO; R1 = aryl, heteroaryl, 1-alkenyl, and alkyl) and Grignard reagents (R2MgX; R2 = primary alkyl and aryl). Thus, a variety of enantiomerically enriched secondary alcohols (R1CH*(OH)R2) can be prepared. It has also been demonstrated that functionalized aryl Grignard reagents can be employed to generate highly functionalized diarylmethanols. The preparative utility of the method has been shown by the fact that the reaction is operationally simple, can be carried out on a 10-mmol scale without any difficulty, and the ligands can be readily recovered.
- Muramatsu, Yusuke,Kanehira, Shinichi,Tanigawa, Masato,Miyawaki, Yuta,Harada, Toshiro
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experimental part
p. 19 - 32
(2010/03/25)
-
- Cobalt-catalyzed addition reaction of organoboronic acids with aldehydes: Highly enantioselective synthesis of diarylmethanols
-
Predicted outcomes: The addition reaction of organoboronic acids with aldehydes in the presence of K2CO3 catalyzed by CoI 2/ACHTUNGRE(R,R)-BDPP gives chiral secondary alcohols in excellent yields with 90-99 % enantiomeric excess (see scheme; (R,R)-BDPP = (2R,4R)-(+)-2,4-bis(diphenyl-phosphino)pentane). This method provides an alternative to prepare an R and S enantiomeric pair by using the same chiral ligand and allows the stereochemical outcome of the reaction to be predicted.
- Karthikeyan, Jaganathan,Jeganmohan, Masilamani,Cheng, Chien-Hong
-
supporting information; experimental part
p. 8989 - 8992
(2010/10/02)
-
- Chiral triphenylprolinol ligands for the efficient catalytic asymmetric arylation of aldehydes
-
The synthesis of new chiral amino alcohols by Heck arylation of an enecarbamate is described. These compounds were used as chiral ligands for the catalytic asymmetric arylation of aldehydes and can be easily recovered. Chiral, nonracemic diarylmethanols were obtained in high yields and enantioselectivities.
- Moro, Angelica Venturini,Tiekink, Edward R. T.,Zukerman-Schpector, Julio,Luedtke, Diogo S.,Correia, Carlos Roque D.
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experimental part
p. 3696 - 3703
(2010/09/05)
-
- Chiral 1,1′-binaphthylazepine-derived amino alcohol catalyzed asymmetric aryl transfer reactions with boroxine as aryl source
-
Using chiral 1,1′-binaphthylazepine-derived amino alcohol as catalyst, the direct addition of in situ prepared arylzinc (with triphenylboroxine as aryl source) to various aryl aldehydes can afford optically active diarylmethanols in high yields and enantioselectivities (up to 96%).
- Liu, Can,Guo, Zong-Liang,Weng, Jiang,Lu, Gui,Chan, Albert S. C.
-
experimental part
p. 159 - 164
(2010/09/04)
-
- Copper(II) acetate-catalyzed addition of arylboronic acids to aromatic aldehydes
-
A novel copper-catalyzed protocol for the synthesis of carbinol derivatives has been developed. In the presence of copper(II) acetate and dppf, carbinol derivatives were prepared by the addition of arylboronic acids to aromatic aldehydes in good to excellent yields. Moreover, the rigorous exclusion of air or moisture is not required in these transformations.
- Zheng, Hanmei,Zhang, Qiang,Chen, Jiuxi,Liu, Miaochang,Cheng, Shuanghua,Ding, Jinchang,Wu, Huayue,Su, Weike
-
experimental part
p. 943 - 945
(2009/06/20)
-
- Efficient chemoselective addition of grignard reagents to carbonyl compounds in 2-methyltetrahydrofuran
-
Compared with tetrahydrofuran (THF) as a solvent for the addition reactions between Grignard reagents and carbonyl compounds 2-methyltetrahydrofuran affords the corresponding adducts in higher yields with higher chemoselectivities. Moreover, 2-methyltetrahydrofuran can be readily recycled and reused, which lowers the cost of the process and makes the reaction greener.
- Zhong, Weihui,Wu, Yaotiao,Zhang, Xingxian
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experimental part
p. 370 - 373
(2009/12/25)
-
- Asymmetric 1,4-addition of organoboronic acids to α,β-unsaturated ketones and 1,2-addition to aldehydes catalyzed by a palladium complex with a ferrocene-based phosphine ligand
-
A combination of palladium with ferrocene-based phosphine ligand with a carbon-bromine bond was found to be a good catalyst for the 1,4-addition of arylboronic acids to α,β-unsaturated ketones and the 1,2-addition to aldehydes. Using Pd(dba)2 and (S,Rp)-[1-(2-bromoferrocenyl)ethyl]diphenylphosphine (S,Rp)-1, 3-phenylcyclohexanone was obtained from the reaction of 2-cyclohexen-1-one with phenylboronic acid in the presence of K2CO3 in toluene at room temperature after 3 h in 92% yield with 76% ee. In the 1,2-addition of 4-methylphenylboronic acid to benzaldehyde, 96% of (4-methylphenyl)phenylmethanol was afforded after 24 h, while the enantiomeric excess was only 6%.
- Suzuma, Yoshinori,Hayashi, Shoko,Yamamoto, Tetsuya,Oe, Yohei,Ohta, Tetsuo,Ito, Yoshihiko
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experimental part
p. 2751 - 2758
(2010/04/26)
-
- Catalytic asymmetric aryl transfer reactions to aldehydes with grignard reagents as the aryl source
-
A study was conducted to demonstrate a practical and efficient method for asymmetric arylation of aldehydes, using aryl Grignard reagents in combination with titanium tetraisopropoxide. It was demonstrated that a variety of diarylmethanols can be obtained
- Muramatsu, Yusuke,Harada, Toshiro
-
experimental part
p. 10560 - 10563
(2009/12/01)
-
- Hydroxyalkyl thiazolines, a new class of highly efficient ligands for carbonyl additions
-
Hydroxyalkyl thiazoline ligands can easily be obtained in an isonitrile-based multicomponent reaction. These ligands are significantly more stable than the comparable oxazoline ligands, and give excellent enantiomeric excess in carbonyl additions of alkyl- and arylzinc compounds. Georg Thieme Verlag Stuttgart.
- Bauer, Michael,Maurer, Frauke,Hoffmann, Svenja M.,Kazmaier, Uli
-
experimental part
p. 3202 - 3207
(2009/06/05)
-
- Application of β-hydroxysulfoximines in catalytic asymmetric phenyl transfer reactions for the synthesis of diarylmethanols
-
(Chemical Equation Presented) Enantiomerically enriched diarylmethanols have been prepared by catalyzed asymmetric phenyl transfer reactions onto aromatic aldehydes with use of readily available β-hydroxysulfoximines as catalysts. As the aryl source, combinations of diethylzinc with either diphenylzinc or triphenylborane have been applied affording arylphenylmethanols with up to 93% ee in good yields. Various functionalized aldehydes and heterocyclic substrates are tolerated, yielding synthetically relevant products.
- Sedelmeier, Joerg,Bolm, Carsten
-
p. 8859 - 8862
(2008/03/12)
-
- Synthesis and evaluation of 4/5-hydroxy-2,3-diaryl(substituted)-cyclopent- 2-en-1-ones as cis-restricted analogues of combretastatin A-4 as novel anticancer agents
-
A new series of 2,3-diaryl-4/5-hydroxy-cyclopent-2-en-1-one analogues replacing the cis double bond of combretastatin A-4 (CA-4) by 4/5-hydroxy cyclopentenone moieties was designed and synthesized. The analogues displayed potent cytotoxic activity (ICsub
- Gurjar, Mukund K.,Wakharkar, Radhika D.,Singh, Anu T.,Jaggi, Manu,Borate, Hanumant B.,Shinde, Popat D.,Verma, Ritu,Rajendran, Praveen,Dutt, Sarjana,Singh, Gurvinder,Sanna, Vinod K.,Singh, Manoj K.,Srivastava, Sanjay K.,Mahajan, Vishal A.,Jadhav, Vinod H.,Dutta, Kakali,Krishnan, Karthik,Chaudhary, Anika,Agarwal, Shiv K.,Mukherjee, Rama,Burman, Anand C.
-
p. 1744 - 1753
(2008/02/02)
-
- Remarkably efficient enantioselective titanium(IV)-(R)-H 8-BINOLate catalyst for arylations to aldehydes by triaryl(tetrahydrofuran)aluminum reagents
-
Novel asymmetric triarylaluminum AlAr3(THF) additions to aldehydes catalyzed by 10 mol % of the titanium(IV) complex of (R)-H8-BINOL ligand are reported. The catalytic system is extremely efficient with reactions completing within 10 min. The system applies to the most diversified aldehydes to date, and more than 20 aldehydes were examined to afford diarylmethanols having an electron-donating or an electron-withdrawing group at the 2-, 3-, or 4-position on the aryl moiety, linear or branched 1-aryl aliphatic alcohols, aryl furyl methanols, 1-aryl allylic alcohols, and, especially, 1-aryl propargylic alcohols in excellent enantioselectivities of ≥90% ee, except for the case of 1-naphthyl addition to benzaldehyde. Noteworthily, diarylmethanols in both R- and S-configurations can be obtained. Copyright
- Wu, Kuo-Hui,Gau, Han-Mou
-
p. 14808 - 14809
(2008/02/09)
-
- Highly enantioselective addition of in situ prepared arylzinc to aldehydes catalyzed by a series of atropisomeric binaphthyl-derived amino alcohols
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The direct addition of in situ prepared arylzinc to aldehydes with chiral binaphthyl-derived amino alcohols as catalysts can afford optically active diarylmethanols in high yields and with excellent enantioselectivities (up to 99% ee, ee = enantiomeric excess). By using a single catalyst, both enantiomers of many pharmaceutically interesting diarylmethanols can be obtained by the proper combination of various arylzinc reagents with different aldehydes; this catalytic system also works well for the phenylation of aliphatic aldehydes to give up to 96 % ee.
- Lu, Gui,Kwong, Fuk Yee,Ruan, Ji-Wu,Li, Yue-Ming,Chan, Albert S. C.
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p. 4115 - 4120
(2007/10/03)
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- Carbinol derivatives via rhodium-catalyzed addition of potassium trifluoro(organo)borates to aldehydes
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Reaction of potassium aryltrifluoroborates with aldehydes, in the presence of a rhodium catalyst, afforded carbinol derivatives in high yields under mild aqueous conditions; this efficient reaction proved to be general, allowing the production of highly hindered diarylmethanols and aliphatic aldehydes were also reactive under these conditions. The Royal Society of Chemistry 2005.
- Pucheault, Mathieu,Darses, Sylvain,Genet, Jean-Pierre
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p. 4714 - 4716
(2007/10/03)
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- Nuclear magnetic resonance spectroscopical studies of 2-carbonyl derivatives of five-membered monohetero-cycles and determination of aromaticity indices
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1H And 13C chemical shifts of formyl, acetyl, benzoyl, and methoxycarbonyl derivatives of benzene, thiophene, pyrrole and furan in chloroform-d, methanol-d4, and DMSO-d6 are examined. Deviation of the signals of the ring protons and carbonyl carbons provide bases for estimating the indices of aromaticity of the heterocycles. The exceptionally large carbonyl stretching vibration of furan derivatives and correlations of the stretching frequencies with the reactivities of the carbonyl groups are discussed.
- Jeon, Kyu Ok,Yu, Ji Sook,Lee, Chang Kiu
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p. 2685 - 2705
(2007/10/03)
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- Rhodium-catalyzed addition of arylstannanes to carbon-heteroatom double bond
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The addition of arylstannanes to the carbon-heteroatom double bond in the presence of a catalytic amount of a cationic rhodium complex ([Rh(cod)(MeCN)2]BF4) was examined. The reactions of aldehydes, α-dicarbonyl compounds, and N-substituted aldimines with the arylstannanes gave corresponding alcohols, α-hydroxy carbonyl compounds, and amines, respectively. An arylrhodium complex generated by the transmetalation with the arylstannane was probably the active catalytic species.
- Oi, Shuichi,Moro, Mitsutoshi,Fukuhara, Hiroe,Kawanishi, Takanori,Inoue, Yoshio
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p. 4351 - 4361
(2007/10/03)
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- Intramolecular reactions of alkynes with furans and electron rich arenes catalyzed by PtCl2: The role of platinum carbenes as intermediates
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5-(2-Furyl)-1-alkynes react, with PtCl2 as catalyst, to give phenols. On the basis of DFT calculations, a cyclopropyl platinacarbene complex was found as the key intermediate in the process. The cyclopropane and dihydrofuran rings of this intermediate open to form a carbonyl compound, which reacts with the platinum carbene to form an oxepin, which is in equilibrium with an arene oxide. When the reaction is carried out in the presence of water, dicarbonyl compounds are obtained, which support the proposed mechanism. Other cyclizations of alkynes with furans or electron-rich arenes give products of apparent Friedel-Crafts-type reactions, although these processes could also proceed by pathways involving the formation of cyclopropyl platinum carbenes.
- Martin-Matute, Belen,Nevado, Cristina,Cardenas, Diego J.,Echavarren, Antonio M.
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p. 5757 - 5766
(2007/10/03)
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- On the stereoselectivity of the Paternò-Büchi reaction between carbonyl compounds and 2-furylmethanol derivatives. The case of aliphatic aldehydes and ketones
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The Paternò-Büchi reaction between 2-furylmethanol derivatives and aliphatic aldehydes and ketones induced by irradiation through Vycor at 8°C shows high regioselectivity but no stereoselectivity. This behaviour can be rationalised by assuming that this type of compound reacts through both singlet and triplet excited states. Ab initio calculations are in agreement with the formation of the 1,4-biradical. The more stable biradical accounts for the observed regioselectivity. The lack of stereoselectivity was discussed on the basis of two hypotheses. The allylic strain proposed by Adam does not account for the observed results. On the contrary, hydrogen bond interaction between (triplet excited) carbonyl oxygen and hydroxy group is able to describe the observed behaviour.
- D'Auria, Maurizio,Emanuele, Lucia,Poggi, Gabriella,Racioppi, Rocco,Romaniello, Gianfranco
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p. 5045 - 5051
(2007/10/03)
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- NOVEL PROCESSES FOR THE PREPARATION OF SUBSTITUTED PROPENONE DERIVATIVES
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The present invention provides industrial and commercial processes for the preparation of 2-acyl-5-benzylfuran derivatives, 1,2,4-triazole-3-carboxylic acid ester derivatives and propenone derivatives having anti-HIV activities and usuful crystals thereof. wherein R1, R2 and R4 each is independently hydrogen or the like; A is CR6 or N; R6 is hydrogen or the like; Q is a protecting group; and L is a leaving group.
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- Regioselective synthesis of trisubstituted cyclopentadienyl ligands from furans
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1,2,3- And 1,2,4-trisubstituted cyclopentadienyl manganese tricarbonyl compounds have been synthesized regioselectively from furans following a common synthetic strategy. The key steps include the transformation of furylcarbinols into hydroxycyclopentenones followed by the conjugate addition of Grignard reagents under chelation directed conditions. This affords hydroxycyclopentanones which can be dehydrated to cyclopentenones. These compounds are further elaborated into the final targets by the 1,2-addition of organolithium reagents.
- Csák?, Aurelio G.,Contreras, Claudia,Mba, Myriam,Plumet, Joaquín
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p. 1451 - 1454
(2007/10/03)
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- 5,10,15-Triaryl-21,23-dioxacorrole and its isomer with a protruding furan ring
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An oxa-analogue of 5,10,15-triarylcorrole, i.e., 5,10,15-triaryl-21,23-dioxacorrole (21,23-O2Cor)H, where two pyrrole rings are replaced by furan moieties, has been produced by condensation of 2,5-bis(arylhydroxymethyl)furan, 2-phenylhydroxymethylfuran, and pyrrole. 2-Phenylhydroxymethylfuran serves as the suitable synthone to introduce a furan ring with the ability create a direct pyrrole-furan α-α bond. The replacement of 2-phenylhydroxymethylfuran by 3-phenylhydroxymethylfuran led to a nonaromatic isomer of (21,23-O2Cor)H, i.e., (iso-21,23-O2Cor)H, which accommodates two furan rings. The protruding furan is built into the macrocycle via β and β′ carbon atoms with the oxygen atom pointing outward. Crystal structures of the [(21,23-O2Cor)H2]2[ZnCl4] and [(iso-21,23-O2Cor)H2] Cl have been studied by X-ray crystallography. The complex ZnCl42- anion is located in a clam-shell-like cavity formed by two 21,23-dioxacorrole cations of the [(21,23-O2-Cor)H2]2[ZnCl4] unit. The 21,23-dioxacorrole cation is only slightly distorted from planarity. In [(iso-21,23-O2Cor)H2]Cl, the macrocycle is strongly puckered as the internal ring is contracted by two carbon atoms when compared to regular porphyrin. The chloride anion is located over the center of the macrocycle and is involved in two intra (N)···HCl and two intermolecular (C)···HCl interactions to be classified as a tetrafurcate system. The (21,23-O2Cor)H molecule preserves aromaticity of the parental corrole with characteristic downfield positions of furan and pyrrole resonances in 1H NMR accompanied the NH resonance at the upfield position (-2.53 ppm). The temperature- dependent features detected in 1H NMR spectra of (21,23-O2Cor)H are consistent with the existence of a tautomeric equilibrium which involves two tautomers alternatively protonated on N(22) or N(24) nitrogen atoms. The density functional theory (DFT) has been applied to model the molecular and electronic structure of two tautomers of 21,23-dioxacorrole {22-N, 24-NH}, {22-NH, 24-N}. The total energies calculated using the B3LYP/6-31G**//B3LYP/6-31G* approach demonstrate a very small energy difference (1.4 kcal/mol) between tautomers suggesting their simultaneous presence in equilibrium. Insertion of nickel(II) into (21,23-O2Cor)H yields five-coordinate (21,23-O2Cor)NiIICl-the first high-spin nickel(II) in a corrole-like macrocyclic environment.
- Pawlicki, Millosz,Latos-Grazynski, Lechosllaw,Szterenberg, Ludmilla
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p. 5644 - 5653
(2007/10/03)
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