(6S,7S,8R,8aR)-6,7,8-Trihydroxyindolizidine (1) and its (7R)-deoxyfluoro analogue (2) was synthesised from 5,8-benzyloxycarbonylimino-5,6,7,8-tetradeoxy-1,2-O-isopropylidene-alpha-D-gluco-octose (3). The key step is an oxidation-reduction sequence. Introduction of a fluoro substituent at C-3 (6) was readily effected by displacement of the 3-trifluoromethanesulfonyl (triflate) group with tris-(dimethylamino)-sulfonium-difluorotrimethylsilicate (TASF).
(6S,7S,8R,8aR)-6,7,8-
三羟基吲哚嗪啶(1)及其(7R)-去氧
氟类似物(2)是由5,8-苯甲氧基亚
氨基-5,6,7,8-四去氧-1,2-O-异丙基甲基-C-α-D-葡萄-八糖(3)合成的。关键步骤是氧化还原序列。在C-3位引入
氟代基团(6)是通过用三甲基甲
硅烷二
氟化物甲基
硫酸酯(TASF)取代3-三
氟甲基磺酸酯(triflate)基团来实现的。