Absolute Configurations of the cis- and trans-13-Methyltetrahydroprotoberberines. Total Synthesis of (+)-Thalictricavine, (+)-Canadine, (+/-)-, (-)-, and (+)-Thalictrifoline, and (+/-)-, (-)-, and (+)-Cavidine

Article abstract of DOI:10.1021/jo00336a024

The tetrahydroprotoberberine alkaloids (+)-thalictricavine <(+)-6> and (+)-canadine <(+)-23> have been synthesized from an optically resolved (+)-13-carboxy-7,8,13,14-tetrahydro-9-oxoprotoberberine <(+)-26>.This establishes the absolute configuration of (+)-thalictricavine as 13S,14R. (+)-Thalictrifoline <(+)-2> and (+)-cavidine <(+)-1> have also been prepared from a common intermediate, (+)-32, whose absolute configuration was established by correlation with (+)-26.This determines the absolute configuration of (+)-thalictrifoline as 13R,14R, of (+)-corydalic acid methyl ester (22) as 3R,4R, and of the protopine (+)-corycavine (20) as 13R.