Studies on antihepatitic drugs. Total synthesis of (+/-)schizandrin C and its analogs

This paper reports the total synthesis of (+/-) schizandrin, C, namely 5,6,7,8-tetrahydro-1, 12-dimethoxy-2, 3, 10, 11-bismethylenedioxy-6, 7-cis-dimethyldibenzo (a, c) cyclooctene (12B), a new active SGPT lowering principle isolated from the Chinese medical plant Schizandra chinensis, and its 6, 7-trans-dimethyl isomer (16B). We also synthesized two more isomers, namely 5, 6, 7, 8-tetrahydro-3, 10-dimethoxy-1, 2, 11, 12-bismethylenedioxy-6, and 7-cis-(and trans-) dimethyldibenzo (a, c) cyclooctene (12A and 16A). The NMR, UV and mass spectra of these four isomers are discussed. IR (in chloroform), UV, NMR and MS of synthetic schizandrin C (12B) are identical with those of the natural compound.

Two new SiC polytypes belonging to the [(44) n 43]3 structure family

Using a modified Laue method as well as electron diffraction and lattice image methods, two new poly types of SiC, 93R and 261R, have been found which belong to a new structure family [(44) n 43]3 based on 8H (44) stacking.