selective aldol reaction mediated by boron compounds and a mild organic base (DBU) was developed. Inclusion of electron-withdrawing groups in the amino acid derivative ligands reacted with BH3·SMe2 forms a boron promoter with increased Lewis acidity at the boron atom and facilitated the carboxylic acid selective enolate formation, even in the presence of other carbonyl groups such as amides, esters, ketones
Verfahren zur Herstellung von 3-Heteroaryl-3-hydroxy-propansäurederivaten durch enantioselektive mikrobielle Reduktion
申请人:Saltigo GmbH
公开号:EP1405917B1
公开(公告)日:2013-08-14
Sterically Hindered Chiral Ferrocenyl P,N,N-Ligands for Highly Diastereo-/Enantioselective Ir-Catalyzed Hydrogenation of α-Alkyl-β-ketoesters via Dynamic Kinetic Resolution
作者:Chuan-Jin Hou、Xiang-Ping Hu
DOI:10.1021/acs.orglett.6b02828
日期:2016.11.4
A new class of sterically hindered chiral ferrocenyl P,N,N-ligands have been prepared through a two-step transformation from (Sc,Rp)-PPFNH2, in which a new (R)-stereogenic center at the pyridinylmethyl position was generated in high diastereoselectivity. With these newly developed P,N,N-ligands, Ir-catalyzed asymmetric hydrogenation of various α-alkyl-substituted β-aryl-β-ketoesters via dynamic kinetic
Microbiological asymmetric reduction of methyl 2-methyl-3-(2-thienyl)-3-oxopropionate (3) by various yeasts was carried out. When Kloeckera saturnus was used, the C3-(S)-alcohols 4c and 4d were obtained, whereas other yeasts such as Lipomyces starkeyi, Saccharomyces fermentati, and Sporobolomyces salmonicolor produced the isomeric C3-(R)-alcohols 4a and 4b. On the other hand, when Endomycopsis fibligera, Hansenula anomala, and Candida albicans were used, the C2-(S)-reduction products 4b and 4c were obtained.