Fritsch's cyclization of N-(a-veratrylveratry1idene)-an~inoacetal in sulphuric acid was shown to give 1.1% of papaverine and 23% of an isomer, n1.p. lG4.5-165.5"C.; hydrochloride, m.p. 212°C. decomp., which was supposed to be 4,5-bis(3,4-dirnethoxypheny1)-2fI-pyrrolenine, produced by an internal condensation of the acetal or the corresponding aldehyde with the reactive methylene group. A similar structure was proposed for another unidentified isomer prepared by Schlittler and Miiller. Ilydrogenation of Fritsch's acetal gave N-(a-veratrylveratry1)-aminoacetal, m.p. 69.5-7O0C., which was cyclized to a base, m.p. 155.5-156°C.; N-aceiyl derivative, m.p. 203.5-204"C., formulated as 2,3-bis(3,4-dimethoxypheny1)-3-pyrroline. Substances pres~imed t o be the intermediate aldehyde and aldol were isolated as colorless oils. Condensation of the dil-&one veratril with aminoacetal, followed by cyclization of the crude product, constituted a new two-step synthesis of papaveraldine in 8y0 yield, and the reduction of the latter to papaverine was known.Other crystalline compounds prepared incidentally and thought to be new were veratril monoanil, m.p. 172-173°C.; a,al-biveratrylidenean~ii~oacetal, m.p. 101-102°C. ; a compound formulated as 2,3-bis(3,4-dimethoxyphenyl)-4-ethylmercaptopyrrolidine hydrochloride, m.p. 184-185°C.; from this a n unidentified mercury complex, n1.p. 109°C. decornp.; 4,4'dibe11zylosy-3,3'-dimethoxydesoxybenzoin, n1.p. 141-142°C.; and its osime, m.p. 137.5"C.
