Approaches to the enantioselective synthesis of the useful building blocks (2R)- and (2S)-2-benzyloxy-2(H)-pyran-3(6H)-one (12 and 17, respectively) are described. The most direct and highly yielding route for the synthesis of 12 was based on the ‘one-pot’ preparation of benzyl 2-O-acetyl-arabinopyranoside 3,4-thionocarbonates (7 and 14) from benzyl β-l- or β-d-arabinopyranosides (1 and 13). Trimethylphosphite-promoted olefination, followed by O-deacetylation and oxidation gave the optically pure enantiomeric enones 12 and 17 in about 50% overall yield.
本文介绍了对映体选择性合成有用构筑物 (2R)- 和 (2S)-2- 苄氧基-2(H)-
吡喃-3(6H)-酮(分别为 12 和 17)的方法。合成 12 的最直接和高产路线是基于从苄基 ²-l- 或 ²-d- 阿拉伯
吡喃糖苷(1 和 13)"一步法 "制备苄基 2-O- 乙酰基-阿拉伯
吡喃糖苷 3,4-
硫代
碳酸酯(7 和 14)。通过
亚磷酸三甲基酯促进的烯化反应,然后进行 O-去乙酰化和氧化反应,得到了光学纯度为 50%的对映体烯酮 12 和 17。