Copper‐Catalyzed Enantioselective Reductive Aldol Reaction of α,β‐Unsaturated Carboxylic Acids to Alkyl Aryl Ketones: Silanes as Activator and Transient Protecting Group
The first reductivealdolreaction of α,β-unsaturated carboxylic acids was developed in the presence of copper/bisphosphine catalysts. The reaction demonstrated the usability of in situ protection of α,β-unsaturated carboxylic acids by a hydrosilane for the reductive C−C bond formation. The Si−O bond in the aldol products is readily cleaved by a standard workup, showing the silane worked as not only
An asymmetric reductive aldol-type reaction of α,β-unsaturated esters with carbonyl compounds using Rh catalyst and Et2Zn was investigated. A chiral zinc complex from α,β-unsaturated ester was easily generated as the key intermediate from Et2Zn and Wilkinson's catalyst with diisopropyl L-(+)-tartrate to give a variety of enantioenriched β-hydroxy esters. The reaction was also applied to the intramolecular
A highly enantioselective method for the synthesis of β‐hydroxy esters via reductive aldolreaction of acrylates with aryl and heteroaromatic ketones is described. In situ generated catalyst composed of zinc acetate and chiral diamine afforded enantioenriched tertiary alcohols in high yields and with excellent enantioselectivity (up to 91% ee). This is also the first successful application of the zinc