Asymmetric synthesis of (−)-epi-blastmycinone and (2R,3S,4S)-3-hydroxy-4-methyl-2-(1′-n-tetradecyl)-butanolide via a tungsten-mediated cyclization reaction

Enantiocontrolled syntheses of the natural lactones 1 and 2 were achieved based on a tungsten-mediated cyclization. The whole syntheses comprise of six or seven steps from readily available 1-trimethylsilyl-pent-1-yne; the overall yields are 25 and 28% for 1 and 2, respectively.