Iron- and Bismuth-Catalyzed Asymmetric Mukaiyama Aldol Reactions in Aqueous Media
作者:Taku Kitanosono、Thierry Ollevier、Shū Kobayashi
DOI:10.1002/asia.201301149
日期:2013.12
asymmetric Mukaiyamaaldolreactions of silicon enolates with aldehydes catalyzed by chiral FeII and BiIII complexes. Although previous reactions often required relatively harsh conditions, such as strictly anhydrous conditions, very low temperatures (−78 °C), etc., the reactions reported herein proceeded in the presence of water at 0 °C. To find appropriate chiral water‐compatible Lewisacids for the
Stereoselective Synthesis of Secondary Alkyllithiums and Their Application to Stereoselective Cuprations or Intramolecular Carbolithiations for the Stereoselective Synthesis of Alkylidenecyclobutanes
intramolecular carbolithiation of secondary alkyllithium reagents possessing a remote alkyne moiety was also investigated, allowing the stereoselective production of alkylidenecylobutane derivatives with very high stereocontrol. Secondary alkyllithium reagents were prepared stereoselectively via an iodo–lithium exchange by using tert-butyllithium. The resulting secondary alkyllithiums were converted directly into
Secondary alkyllithium reagents bearing an OTBS group (TBS=tert‐butyldimethylsilyl) at the 3‐position can be prepared stereoconvergently through an I/Li exchange from a diastereomeric mixture of the corresponding secondaryalkyl iodides. These lithium reagents react with a range of electrophiles, including carbon electrophiles, with retention of configuration to yield various 1,3‐difunctionalized derivatives