Anion Relay Enabled [3 + 3]-Annulation of Active Methylene Isocyanides and Ene-Yne-Ketones.

A new anion relay enabled [3 + 3]-annulation of active methylene isocyanides and conjugated ene-yne-ketones was developed for the efficient and straightforward synthesis of biologically valuable furo[3,2-c]pyridine derivatives. In this transformation, a sequential through-bond and through-space anion relay chemistry cascade is involved, which is initiated by an intermolecular Michael addition. Three new bonds and two rings are sequentially constructed from readily available acyclic precursors.