Isochromane-3,4-diones in Direct Vinylogous Aldol Reaction: Scope and Limitations

Herein we report for the first time the use of isochromane-3,4-diones in a direct vinylogous aldol reaction with both aromatic and aliphatic aldehydes, affording the corresponding products in moderate to good yield and with very high diastereoselectivity in most cases. The reaction is enabled by a tertiary amine, which promotes the in situ formation of nucleophilic dienolate via γ-deprotonation of the α-ketoester functionality incorporated within the 3-isochromanone scaffold.