Trifluoromethanesulfonic anhydride–4-(N,N-dimethylamino)pyridine as a reagent combination for effecting Bischler–Napieraiski cyclisation under mild conditions: application to total syntheses of the Amaryllidaceae alkaloids N-methylcrinasiadine, anhydrolycorinone, hippadine and oxoassoanine

Martin G. Banwell ,  Brett D. Bissett ,  Stefan Busato ,  Cameron J. Cowden ,  David C. R. Hockless ,  Jeffrey W. Holman ,  Roger W. Read and Angela W. Wu