43 Benzo〔c〕phenanthridine型alkaloidの合成法の検討

抄録

Some tentative structures [(3)-(8)] have been proposed for the O_5-benzo[c]-phenanthridine alkaloids isolated from Papaverous plants on the basis of their NMR spectra. However, other structures could not be rigidly excluded from consideration, because the NMR data on nitidine type alkaloids did not coincide with the result of the analysis which was used to structural establishment of the above O_5-alkaloids. The direct comparison of those alkaloids to the synthetic specimen may be most powerful tool to the confirmation of the structures of them. Therefore, Robinson's synthetic pathway of the benzo[c]phenanthridine alkaloids was examined on a model compound (9). In the course of the study, the pure cis and trans tetralin formamides (16a and b) and the corresponded amino derivatives (17a and b) were obtained. These experiments disclosed that reduction of the tetralone oxime (19) with Na-Hg gave a cis amino compound (17b) as a rather main product, while such a reaction is well-known to give a thermodynamically controled product, a trans-isomer. And also the cis-and trans-derivatives of tetrahydro-(22a and b) and hexahydrobenzo[c]phenanthridine (23a and b) were prepared. Furthermore, it was found that Bischler-Napieralski cyclization of the formamide (38) which has no methoxy group at the para position could not proceed.