SYNTHESIS OF POLYPROPIONATES AND CARBOHYDRATES

描述：据称， 聚丙酸酯、碳水化合物和相关的天然产物是 这些化合物的方法利用了最近的发现， (1)更大的丙二烯基锡烷和γ-（烷氧基）烯丙基锡烷， 可以容易地制备大于95%ee，和（2）这些试剂 通过高选择性的SE'途径与醛缩合。应注意 丙二烯基锡烷进行Cram或螯合控制添加 导致顺式，顺式;反式，顺式;顺式，反式;或 反式，反式产物取决于反应条件。该反应 据说在聚丙酸酯抗生素方面有潜在的应用 合成.主要研究者指出， 简单和复杂的单糖是基于对γ- （烷氧基）烯丙基锡烷进行非对映和对映选择性加成 得到单保护的高烯丙基1，2-二醇的醛， 光学纯度大于95%。他指出，对于非外消旋的α-烷氧基， 醛显着增强，实现非对映选择性 通过试剂/底物匹配。据说这种方法是 特别有吸引力，因为它允许制备 5-10个碳的差异保护的复合单糖， 容易获得的手性池起始材料。值得注意的是， 中间体是糖缀合物和低聚物的前体， 潜在的抗生素和抗肿瘤特性。最后指出， 该方法也适用于α-氨基醛， 某些亚胺，从而允许合成各种生物学上的 具有高度立体化学控制的活性氨基糖。

DESCRIPTION: It is stated that routes to biologically active polypropionates, carbohydrates, and related natural products are proposed and that approaches to these compounds utilize recent findings (1) that allenyl stannanes and gamma-(alkoxy)allyl stannanes of greater than 95% ee can be readily prepared, and (2) that these reagents condense with aldehydes by highly selective SE' pathways. It is noted that the allenylstannanes undergo Cram or chelation controlled additions to alpha-chiral aldehydes leading to syn,syn; anti,syn; syn, anti; or anti,anti products depending on reaction conditions. This reaction is said to have potential applications to polypropionate antibiotic synthesis. The principal investigator notes that the proposed route to simple and complex monosaccharides is based on observations that gamma- (alkoxy)allylstannanes undergo diastereo- and enantioselective additions to aldehydes affording monoprotected homoallylic 1,2-diols of greater than 95% optical purity. He indicates that with nonracemic alpha-alkoxy aldehydes considerably enhanced, diastereoselectivities are realized through reagents/substrate matching. This methodology is said to be particularly attractive because it allows the preparation of differentially protected complex monosaccharides of 5-10 carbons from readily available chiral pool starting materials. It is noted that such intermediates are precursors to glycoconjugates and oligomers with potential antibiotic and antitumor properties. It is finally indicated that the methodology is also applicable to alpha-amino aldehydes and certain imines, thus allowing for the synthesis of various biologically active amino sugars with high stereochemical control.