Total Synthesis of (+)‐trans‐Dihydronarciclasine by a Catalytic Enantioselective Regiodivergent Nitroso Diels–Alder Reaction

A novel approach to enantiomerically pure (+)-trans-dihydronarciclasine (1), a biologically active natural product of the Amaryllidaceae group, uses a catalytic enantioselective regiodivergent nitroso Diels–Alder reaction as the key step. Compound 1 is prepared in a 17-step synthesis in 5.6 % overall yield.