An efficient enantioselective approach to multifunctionalized -butyrolactone: concise synthesis of (+)-nephrosteranic acid

A short, efficient and novel approach for multifunctionalized gamma-butyrolactone paraconic acids and its application to the total synthesis of (+)-nephrosteranic acid from readily available PMB (R)-glycidyl ether as a starting material are described. Key transformations include asymmetric Michael addition catalyzed by chiral diphenylprolinol silyl ether and stereoselective alpha-methylation.