The synthesis of (-)-acetomycin 1, a highly functionalized gamma-lactone with antitumer activity, was achieved in five steps with nearly comlete enantioselectivity. The key step was realized by a large scale lipase R catalyzed esterification 0f 5-hydroxy-4-methyl-2(5H)-furanone 2 providing (-)-(5R)-5-acetoxy-4-methyl-2(5H)-furanone 3 with an e.e of 99%.
