3. 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,Angela W. Wu J. Chem. Soc. Chem. Commun. 1995 2551
