A Concise and Enantioselective Approach to Cyclobutanones by Tandem Asymmetric Epoxidation and Enantiospecific Ring Expansion of Cyclopropylidene Alcohols. An Enantiocontrolled Synthesis of (+)- and (-)-α-Cuparenones

Article abstract of DOI:10.1021/jo00032a021

A tandem Katsuki-Sharpless asymmetric epoxidation and enantiospecific ring expansion of 2-alkyl(or 2-aryl)-2-cyclopropylideneethanols (1a-i) afforded chiral 1-alkyl(or 1-aryl)-1-(hydroxymethyl)cyclobutanones (3a-i) in high yields and high enantiomeric excess.These compounds are potentially valuable synthons for the enantioselective creation of the quaternary carbons.Hence, this enabled us to accomplish a concise and enantioselective total synthesis of both (+)- and (-)-cuparenones (11).