Studies on the narciclasine alkaloids: Total synthesis of (+)-narciclasine and (+)-pancratistatin

Enantioselective total syntheses of the antitumor alkaloids. (+)-narciclasine and (+)-pancratistatin, are reported. These syntheses feature a stereo- and regiocontrolled aryl enamide photocyclization to construct a common, advanced intermediate possessing a trans-fused BC substructure. Differential functional group interchange in the C-ring of this phenanthridone core structure allows for the production of the two target natural products in enantiomerically pure form.