A Short Asymmetric Synthesis of the Benzopyrano[3,4‐c]pyrrolidine Core via an Organocatalytic Domino Oxa‐Michael/Michael Reaction

A short and highly stereoselective asymmetric synthesis of 3,4‐ trans ‐disubstituted chromans employing nitrovinylphenols and acrolein as precursors via a domino oxa‐Michael/Michael reaction is described. This cascade was efficiently catalyzed by diphenylprolinol TMS ether furnishing the products in good to excellent yields (62–91%) and excellent stereoselectivities ( dr : 94:6–97:3, 93–98% ee ). The domino products can be converted into the corresponding N ‐alkylated trans ‐benzopyrano[3,4‐ c ]pyrrolidines through a reductive amination/ N ‐alkylation sequence. This was demonstrated for the case of a descyano derivative of S33138.