Synthesis,resolution, and absolute stereochemistry of (-)-blestriarene C |
| |
Authors: | Hattori Tetsutaro Shimazumi Yuhi Goto Hitoshi Yamabe Osamu Morohashi Naoya Kawai Wataru Miyano Sotaro |
| |
Institution: | Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aramaki-Aoba 07, Aoba-ku, Sendai 980-8579, Japan. hattori@orgsynth.che.tohoku.ac.jp |
| |
Abstract: | A naturally occurring 1,1'-biphenanthrene, blestriarene C (1), was prepared in 13 steps and 30% overall yield. The key steps are the ester-mediated nucleophilic aromatic substitution on 2,6-di-tert-butyl-4-methoxyphenyl 5-isopropoxy-2-methoxybenzoate (4) by 2-methoxy-4-methoxymethoxy-6-methylphenylmagnesium bromide (5) and a novel intramolecular cyclization of the resulting 4-isopropoxy-2'-methoxy-4'-methoxymethoxy-6'-methylbiphenyl-2-carboxylic ester 14 to 7-isopropoxy-4-methoxy-2-(methoxymethoxy)phenanthren-9-ol (15). The racemic blestriarene C was optically resolved by chiral HPLC on a preparative scale to give several 10-mg yields of both the enantiomers in up to 95% ee. The absolute stereochemistry was determined to be S(a)-(-) by the axial chirality recognition method, which was based on the stereospecific formation of a 12-membered cyclic diester containing two biaryl-o,o'-diyl unites joined by ester -CO(2)- linkages. The validity of the method was confirmed by an X-ray crystallographic analysis and ab initio conformational analyses of such 12-membered cyclic diesters. It was found that blestriarene C and its 7,7'-diisopropyl ether 2 underwent rapid photoracemization even under ambient light exposure. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|