Treatment of colchicine with concentrated sulfuric acid at 80-90 "C afforded besides 2-demethylcolchicine a mixture of catecholic colchicines which could be separated and identified. Similar treatment of 1-demethyland 3-demethylcolchicine gave predominantly the 1,2-catechol or ita 2,3 isomer. Methylenation of these catechols afforded the colchicine congeners 1 and 10. A comparison with natural cornigerine revealed that the alkaloid was identical with the 2,3-methylenedioxy compound 10 and not with 1, as formerly proposed.Cornigerine, an alk@oid from Colchium cornigerum species, was isolated by Santae et al. in 19612 and reported to exhibit similar biological activities as ~olchicine.~ Structure 1 for cornigerine, with a 1,Bmethylenedioxy ring annulated to the aromatic ring A of colchicine replacing the two original methoxy groups, was proposed on the basis of a 'H NMR analysis and by chemical degradation4 (see structures 1 and 10). It isinteresting to note that the -0OMe 10 CORNIGERINE postulated structure of cornigerine differed in the aromatic A region with respect to the methylenedioxy substitution pattern from that established for the accompanying minor alkalcjds CC-20 and CC-!L5 It was also interesting to note that Santavjr's groups concluded that the singlet at 6 6.01 marked the protons of the methylenedioxy group, contrary to reporta that hindered aromatic methylenedioxy groups have unequal protons, frequently shown as doublets.6These discrepancies, together with a recently accomplished selective 0-demethylation of the ring-A-positioned methoxy groups of colchicine,7S8 suggested the preparation of cornigerine by partial synthesis. Treatment of colchicine (2) with concentrated sulfuric acid at 80-90 "C afforded, besides a small amount of 2-demethylcolchicine (41, the major reaction product obtained at 60 0C,7 a slightly more polar substance (TLC; see structures 2-9). The dark blue color shown after the plate was sprayed with an alcoholic ferric chloride solution hinted that this substance might be of catecholic nature. The same product was formed by similar treatment of 1-demethylcolchicine (3)798 or 2-de-(1) Guest scientist from the Pharmaceutical Division of Hoechst AG, Frankfurt, Federal ublic of Germany.(2) El-Hamidi, A x t a e , F. Collect. Czech. Chem. Commun. 1962, 27, 2111 (3) $anta@, F. Acta. Univ. Palacki. Olomouc. 1979,90, 15-44. We thank Professor $ a n t a e for having sent us a copy of this review article. (4) Cross, A. D.; El-Hamidi, A,; Hrbek, Jr., J.; $ a n t a e , F. Collect. Czech. Chem. Commun. 1964,29, 1187. (5) Battersby, A. R.; Ramage, R.; Cameron, A. F.; Hannaway, C.; $anta@, F.; J. Chem. SOC. C 1971, 3514. (6) Brossi, A.: Blount, J. F.: O'Brien, J.: Teitel, S. J. Am. Chem. Soc. 1971,93,6248. (7) Rasner, M.; Capraro, H A . ; Iorio, M. A.; Jacobson, A. E.; Atwell,
