109053-86-3Relevant articles and documents
Efficient enantioselective synthesis of methyl esters of α-unsubstituted β-hydroxy acids via asymmetric aldol-type addition of chiral boron enolates of (methylthio)acetic acid to aldehydes
Fringuelli, Francesco,Piermatti, Oriana,Pizzo, Ferdinando
, p. 1207 - 1211 (1996)
The aldol-type addition of chiral boron enolates of (methylthio)acetic acid to various aldehydes gives α-(methylthio)-β-hydroxy acids stereoselectively and with good yields. The desulfenylation of methyl esters of the condensation adducts allows methyl es
Over 98% optical yield achieved by a heterogeneous catalysis. Substrate design and analysis of enantio-differentiating factors of tartaric acid-modified Raney nickel hydrogenation
Sugimura, Takashi,Nakagawa, Satoshi,Tai, Akira
, p. 355 - 363 (2002)
Tartaric acid-modified Raney nickel (TA-MRNi) is a chiral heterogeneous catalyst for the hydrogenation of prochiral ketones. An optical yield (OY) of 86% with methyl acetoacetate (1) as a substrate was improved to 94-96% by employing β-keto esters having a proper bulkiness at the γ-position. The γ-bulkiness effect contributes to a high intrinsic enantio-differentiating ability (factor-i) of the TA-MRNi catalysis. Through the study, we found the best substrate, γ-cyclopropyl-β-keto ester, the hydrogenation of which resulted in 98.6% OY. This further improvement in the OY was ascribed to a smaller contribution of non-enantio-differentiating hydrogenation (N-site catalysis) due to the substrate-specific activation of the enantio-differentiating hydrogenation by the chiral modifier. The OY of the hydrogenation of 1 was analyzed by comparing with well-behaved β-keto esters, and the contribution of the factor-i and the N-site to the OY value was evaluated to deduce the origin of the enantiodifferentiation.
Development of Chiral Spiro P-N-S Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of β-Alkyl-β-Ketoesters
Bao, Deng-Hui,Wu, Hui-Ling,Liu, Chao-Lun,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information, p. 8791 - 8794 (2015/11/27)
The chiral tridentate spiro P-N-S ligands (SpiroSAP) were developed, and their iridium complexes were prepared. Introduction of a 1,3-dithiane moiety into the ligand resulted in a highly efficient chiral iridium catalyst for asymmetric hydrogenation of β-alkyl-β-ketoesters, producing chiral β-alkyl-β-hydroxyesters with excellent enantioselectivities (95-99.9 % ee) and turnover numbers of up to 355 000. Bulkyness is the key: New chiral tridentate spiro P-N-S ligands (SpiroSAP) bearing a conformationally constrained 1,3-dithiane moiety were developed. Their iridium catalysts showed excellent enantioselectivities and activity (TON up to 355 000) for asymmetric hydrogenation of β-alkyl-β-ketoesters.
Enzymatic total synthesis of banana volatile (S)-2-pentyl (R)-3-hydroxyhexanoate
Kallergi, Maria,Kalaitzakis, Dimitris,Smonou, Ioulia
experimental part, p. 3946 - 3950 (2011/09/14)
The banana volatile (S)-2-pentyl (R)-3-hydroxyhexanoate has been synthesized in 79 % yield and high optical purity (>99 % ee, >99 % de) starting from methyl 3-oxohexanoate and 2-pentanone. The synthetic method consists of three steps and the key reactions are enzymatic reduction and enzymatic transesterification. Copyright
