Structural and conformational studies on tetrahydroprotoberberine alkaloids

Abstract

Two new tetrahydroprotoberberine alkaloids are reported, one from Corydalisthalictrifolia and the other from Corydalistuberosa. The former is apparently identical with a previously described synthetic compound. The latter is a des-methyl derivative of the first. Both compounds are 13-methyltetrahydroprotoberberines in which the hydrogens at C-13 and -14 are cis to one another. An examination has been made of the p.m.r. spectra of the two new bases and of several 13-methyltetrahydroprotoberberines of established structure and stereochemistry. The spectra can be used to assign the relative stereochemistry of these 13-methyl compounds.