DETERMINATION OF THE STEREOCHEMISTRY OF C-2' AND C-3' POSITIONS OF TAXINE NA-1 (2'-HYDROXYTAXINE II) BY THE ASYMMETRIC SYNTHESIS OF THE REDUCTIVE DEGRADATION PRODUCT OF ITS SIDE CHAIN MOIETY

摘要

The reductive degradation of taxine NA-1 (2'-hydroxytaxine II) with n-Bu4NBH4 gave taxinine A and (-)-3-dimethylamino-3-phenylpropane-1,2-diol (1) in addition to 11,12-dihydrotaxinine A. The relative stereochemistry of (-)-1 was identical with syn-3-dimethylamino-3-phenylpropane-1,2-diol, (±)-1b, which was synthesized from cis-2,3-epoxy-3-phenylpropan-1-ol, (±)-7. The absolute configuration of (-)-1 was certified by comparison of the specific optical rotation and the spectroscopic data of (-)-1 with those of (+)-1b and (-)-1b, which were enantioselectively synthesized by Sharpless asymmetric epoxidation reaction of cis-cinnamyl alcohol (6), respectively. As the result, the relative and absolute configuration of (-)-1 was same with that of (-)-1b possessing (2R, 35) configuration. Thus, the absolute configuration of the side chain of taxine NA-1 (2'-hydroxytaxine II) at C-2' and C-3' positions was determined to be (2'R, 3'S).