Synthesis of 1,2‐Diols and Their Base‐Initiated Rearrangement to Butyrolactones

Abstract

1,2‐Diols 3 have been synthesized by the aldol addition of hydroxy esters 1 to propargyl aldehydes 2 in dichloromethane. These 1,2‐diols undergo a base‐initiated rearrangement under mild conditions in methanol with an unusual 1,2‐alkyl shift to afford interesting α,β‐unsaturated γ‐butyrolactones 4. A possible mechanism is postulated on the basis of experimental evidence and the results of DFT calculations.