Synthesis of spirolactams via Diels-Alder addition of 1,3-butadienes to an α-methylene lactam

Abstract

As part of a programme directed towards the synthesis of the bicyclic spiroimine ring systems present in the marine toxins, the spirolides and gymnodimine, a study of the Diels-Alder addition of dienes 8, 12, cyclopentadiene and 2,3-dimethyl-1,3-butadiene to α-methylene lactam 7 was undertaken. A systematic study of the use of a variety of Lewis acids to catalyze the Diels-Alder reaction was undertaken. Extension of this work to an asymmetric variant of these Diels-Alder reactions was investigated using the chiral Lewis acids [(S,S)-