Organocatalyzed Rearrangement of S-(2-Oxoalkyl)-thioenoates.

The highly Lewis basic amidine-based catalyst DHIP promotes the rearrangement of S-phenacyl thiocinnamate and related thioesters into dihydrothiophene derivatives. In contrast to previously explored rearrangements of thioesters, the reaction proceeds via a novel Dieckmann-like cyclization pathway. An alternative two-component synthesis of the same products has also been developed.