First total synthesis of modiolide A, based on the whole-cell yeast-catalyzed asymmetric reduction of a propargyl ketone

While the first total synthesis of modiolide A (1a), a 10-membered ring lactone with a marine-origin was achieved, an important chiral building block for constructing the chirality at C-4 in 1a, (S)-6-[(4-methoxybenzyl)oxy]-1-trimethylsilyl-1-hexyn-3-ol (3a) was obtained in as high as 96.1% ee. Asymmetric reduction of a silylated propargyl ketone (5) mediated by whole-cell of Pichia minuta IAM 12215 was established. This yeast-mediated reduction was also applicable to provide stereochemically pure (3S,5R)-5-[(4-methoxybenzyl)oxy]-1-trimethylsilyl-1-hexyn-3-ol (15), a synthetic intermediate for the related 10-membered lactone, tuckolide (16).