Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II-Complesso Universitario Monte Sant'Angelo, via Cinthia, 4 I-80126 Napoli, Italy.
J Org Chem. 2010 Jun 4;75(11):3558-68. doi: 10.1021/jo100077k.
An efficient and general de novo synthetic route to enantiomerically pure L-hexoses has been accomplished starting from the heterocyclic homologating agent 5,6-dihydro-1,4-dithiin-2-yl[(4-methoxybenzyl)oxy]methane and methyl alpha,beta-isopropylidene-L-glycerate. The sugar scaffold was constructed by an acid-catalyzed domino reaction, which enabled selective preparation of either methyl 2,3-dideoxy-alpha-L-threo-hex-2-enopyranosides or 1,6-anhydro-2,3-dideoxy-beta-L-threo-hex-2-enopyranose as key intermediates. The subsequent double bond functionalization by syn or anti dihydroxylation reactions allowed introduction of the remaining stereogenic centers, leading to desired orthogonally protected L-hexopyranosides with a high degree of diastereoselectivity and with very good overall yields. These and previous results (based on the use of the corresponding L-erythro epimers) contribute to make our approach general and place it among the few methods able to synthesize the whole series of the rare L-hexoses.
已经完成了一种从杂环同系化试剂 5,6-二氢-1,4-二噻因-2-基[(4-甲氧基苄基)氧基]甲烷和甲基 alpha,beta-亚异丙基-L-甘油酸出发，高效且通用的全合成对映体纯 L-己糖的方法。糖骨架通过酸催化的多米诺反应构建，该反应能够选择性地制备甲基 2,3-二脱氧-α-L-赤型-己-2-烯吡喃糖苷或 1,6-脱水-2,3-二脱氧-β-L-赤型-己-2-烯吡喃糖作为关键中间体。随后通过顺式或反式二羟化反应对双键进行官能化，引入其余的手性中心，得到所需的具有高度非对映选择性和非常好的总收率的正交保护的 L-吡喃糖苷。这些和以前的结果（基于使用相应的 L-赤型差向异构体）有助于使我们的方法具有普遍性，并使其成为能够合成整个罕见的 L-己糖系列的少数几种方法之一。
