Diastereoselective Cascade Assembly of Functionalized Pyrano[3,4‑<i>c</i>]pyrrole Derivatives

A novel convenient approach for the synthesis of densely functionalized pyrano­[3,4-c]­pyrrole derivatives was developed. Cascade transformation of the simple adducts of tetracyanoethylene (TCNE) and ketones (4-oxoalkane-1,1,2,2-tetracarbonitriles) in the presence of aldehyde under the action of acetic acid led to the diastereoselective formation of targeted pyrano­[3,4-c]­pyrroles. The reaction pathway was thoroughly investigated, and proposed intermediates were shown to be consistent with experiment.