Enantioselective Synthesis of (−)-Curcumanolide A Using Enzymatic Transesterification of meso-Spirodiol

meso-Spirodiol 12 and spirodiacetate 13 were stereoselectively prepared using π-face selective Grignard addition to norbornanone 7. Asymmetric transesterification of meso-diol and hydrolysis of meso-diacetate were studied using lipases. Pseudomonas fluorescens lipase-catalyzed transesterification of meso-diol 12 afforded the monoacetate (−)-21 of high enantiomeric excess (>99% ee). The formal synthesis of (−)-curcumanolide A has been achieved from the optically active (−)-21.