Enantioselective Synthesis of Seven-Membered Carbo- and Heterocyles by Organocatalyzed Intramolecular Michael Addition

Abstract

Unprecedented diastereo- and enantioselective synthesis of seven-membered rings has been achieved by organocatalyzed intramolecular Michael addition of enals bearing β-diketone functionality. The cyclization leads to 2,3-disubstituted cycloheptanone derivatives in high yield and excellent stereoselectivity. The same organocatalyzed cyclization process has been used to prepare six-membered homologs, but with lower stereoselectivity.