作者:Pavol Kováč、Bart Ruttens
DOI:10.1055/s-2004-831206
日期:——
Ethyl 2,4-di-O-acetyl-3,6-dideoxy-1-thio-β-l-xylo-hexopyranoside (10) and ethyl 2,4-di-O-benzyl-3,6-dideoxy-1-thio-β-l-xylo-hexopyranoside (12) were synthesized in 60% and 55% overall yield, respectively. Starting from α-l-fucose, sequential peracetylation, anomeric bromination, nucleophilic substitution of the anomeric bromide with NaSEt and deacetylation gave ethyl 1-thio-β-l-fucopyranoside (6). Acid catalyzed regioselective cleavage of the orthoester in ethyl 2-O-acetyl-3,4-O-(1-ethoxyethylidene)-1-thio-β-l-fucopyranoside, prepared from 6, yielded the corresponding 2,4-diacetate, which was deoxygenated at C-3 to provide the disarmed thioglycoside 10. Deacetylation of 10, followed by benzylation, gave armed thioglycoside 12. Several intermediates did not require purification by chromatography.
合成了乙基 2,4-二-O-乙酰基-3,6-二脱氧-1-硫代-δ-²-l-氧基吡喃己糖苷(10)和乙基 2,4-二-O-苄基-3,6-二脱氧-1-硫代-δ-²-l-氧基吡喃己糖苷(12),总收率分别为 60% 和 55%。从δ-l-岩藻糖开始,依次进行过乙酰化、异构体溴化、用 NaSEt 亲核取代异构体溴化物和脱乙酰化,得到乙基 1-硫代-δ-²-l-岩藻糖苷(6)。由 6 制备的 2-O-乙酰基-3,4-O-(1-乙氧基亚乙基)-1-硫代-δ-l-岩藻糖苷中的正酯在酸催化下进行区域选择性裂解,得到相应的 2,4-二乙酸酯,在 C-3 处进行脱氧反应,得到解除了武装的硫代糖苷 10。对 10 进行脱乙酰化,然后进行苄基化,就得到了武装硫代糖苷 12。有几种中间体不需要通过色谱法进行纯化。