Enantioselective bromolactonization using an S-alkyl thiocarbamate catalyst.

The apple never falls far from the tree: S-alkyl thiocarbamate 1 (see scheme, NBP = N-bromophthalimide) was prepared in high yield through a synthetic sequence involving a Newman-Kwart rearrangement of the corresponding O-alkyl thiocarbamates. Compound 1 was used to catalyze bromolactonization, thus providing enantioenriched δ-lactones in excellent yield and enantioselectivity.