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
David CR, et al.
Journal of the Chemical Society. Chemical Communications, 1993(24), 2551-2553 (1995)