Starting from (R)-O-benzylglycidol and a sulfur-stabilized allyl anion
, a (3 + 3) synthesis of the alpha,beta-unsaturated (6S)-delta-lactone
7 is achieved. Subsequent diastereoselective addition of a phenyldime
thylsilyl cuprate and unmasking of the latent hydroxy function provide
s the lactone unit of compactin.