The carbon‐13 NMR signals of twelve cochicinic derivatives, have been assigned and some 1H‐13C coupling constants have been measured. The substituent effects, the colchicine‐isocolchicine isomerism, the prototropy of colchiceine and trimethylcolchicinic acid and the acylotropy of colchiceine acetate are discussed. There is a slight predominance of the isocolchicinic tautomer, both in the case of the prototropy and the acylotropy.
Die Reaktion der Carbonsäuren (I) mit den entsprechenden Aminen (II) und P2S5 in siedendem Pyridin führt zu den sek. (IIIa)‐(IIId) bzw. tertiären Thioamiden (IIIe) bis (IIIg).
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