Dearomatising cyclisation of lithiated 1-naphthamides with a phenylglycinol-derived chiral auxiliary: asymmetric synthesis of an arylkainoid and a kainoid-like pyroglutamate

1-Naphthamides of N-benzylphenylglycinols undergo a diastereoselective dearomatising cyclisation on treatment with t-BuLi and DMPU or HMPA. A new pyrrolidinone ring is formed bearing three new stereogenic centers of defined absolute stereochemistry. Removal of the phenylglycinol auxiliary gives enantiomerically pure substituted lactams exhibiting the stereochemistry of the kainoids. These may be converted to kainoid-like pyroglutamates, or alternatively, using the method of the previous paper, to analogues of acromelic acid.