A convenient preparation of (S)-(−)-4-hydroxy-2-methylcyclopent-2-en-1-one and its application as a chiral synthetic equivalent of 2-methylcyclopent-2-en-1-one in the terpenoid synthesis

A method for the preparation of (S)-4-hydroxy-2-methylcyclopent-2-en-1-one from 1-(2-furyl)ethanol using modified Piancatelli rearrangement and enzymatic kinetic resolution of the racemate was developed. An application of O-protected derivatives of 4-hydroxy-2-methylcyclopent-2-en-1-one to terpenoid synthesis through tandem conjugate addition of allyl-metal reagents, enolate trapping, and consecutive Mukaiyama–Michael addition was studied. An optically active azulene derivative useful for terpenoid synthesis was efficiently synthesized.