THALICTRUM ALKALOIDS .9. ISOLATION STRUCTURAL ELUCIDATION AND SYNTHESIS OF THALISOPAVINE

Evidence is presented for assignment of structure 5 to thalisopavine, a new phenolic alkaloid isolated from the roots of Thalictrum dasycarpum Fisch. and Lall. Elementary analysis and mass spectrometry supported a C20H23NO4 empirical formula. Diazomethane methylation yielded O-methylthalisopavine (6). N-Methylation of 6, followed by Hofmann degradation, gave N-methylisopavinemethine (10), characterized by direct comparison with a sample prepared from isopavine (7). Nmr and mass spectral analogies to amurensine (8) and amurensinine (9) favored assignment of structure 5 for thalisopavine. The structure was confirmed by total synthesis of (±)-thalisopavine by an unequivocal route similar to that used for the synthesis of (±)- isopavine (7). Other phenolic alkaloids isolated include (-)-norargemonine (1), (-)-bisnorargemonine (2), L-(+)-laudanidine (3), and corypalline (4). © 1969, American Chemical Society. All rights reserved.