An enantioselective oxa-Michael–Henry reaction of substituted salicylaldehydes with nitroolefins that proceeds though an aromatic iminium activation (AIA) has been developed by using a chiral secondary amine organocatalyst and salicylic acid as a co-catalyst. The corresponding 3-nitro-2H-chromenes were obtained in moderate-to-good yields with up to 91% ee under mild conditions. Based on the experimental
The asymmetric domino oxa-Michael–Henry reaction of salicylaldehyde derivatives with trans-β-nitro olefins catalyzed by a readily available trans-4-hydroxy-L-prolinamide with 4-nitrophenol as an effective cocatalyst is presented. The corresponding 3-nitro-2H-chromenes were obtained in moderate to excellent yields (up to 99 %) and with up to 90 % ee under mild conditions. In addition, a preliminary