Highly Enantioselective Mukaiyama Aldol Reaction of α,α-Dichloro Ketene Silyl Acetal: An Efficient Synthesis of a Key Intermediate for Diltiazem
作者:Ritsuo Imashiro、Tooru Kuroda
DOI:10.1021/jo026361+
日期:2003.2.1
and high enantioselectivity (96% ee), together with the chiral ligand 13a in nearly quantitative recovery. The reaction using a substoichiometric amount of 12e (20 mol %) also proceeded to excellent yield (88%), with somewhat lower enantioselectivity (77% ee). The aldol product 3a thus obtained was easily converted to (-)-2 in excellent yield (80%) and highopticalpurity (>99% ee). The highly enantioselective
a generic, green synthesis of 17 valuable syn-aryl-(2S,3R)-2‑chloro-3‑hydroxy esters (syn-(2S,3R)-1) in 73%-99% isolated yields along with 6.1:1–83:1 dr and 31%∼>99% ee, through dynamicreductivekineticresolution of racemic aryl α‑chloro β-keto esters (2) catalyzed by an engineered ketoreductase which was obtained via epPCR-based directed evolution. The hectogram scale synthesis of syn-(2S,3R)-1b
A new enantioselective synthesis of glycidates via dynamic kinetic resolution of racemic 2-chloro-3-keto esters using chiral Ru (II) complexes
作者:Jean-Pierre Genêt、M.C. Caño de Andrade、V. Ratovelomanana-Vidal
DOI:10.1016/0040-4039(95)00182-c
日期:1995.3
2-chloro-3-keto esters were quantitatively hydrogenated to syn and anti 2-chloro-3-hydroxyester by asymmetric hydrogenation with chiral ruthenium (Ii) catalysts prepared in-situ from (COD)Ru(2-Methylallyl)(2) in presence of atropisomeric ligands such as MeO-Biphep and Binap, giving enantioselectivity up to 99%. 2-chloro-3-hydroxy esters were treated with different bases to give (E)- and (Z)-2,3-epoxyalkanoates in 65-90% yields with 84-97% ee.