SYNTHESIS OF POLYPROPIONATES AND CARBOHYDRATES

描述：据报道，通往生物活性的路线 聚丙酸酯、碳水化合物和相关的天然产品 并利用最近的发现对这些化合物进行了研究 (1)烯丙基锡烷和伽马-(烷氧基)烯丙基锡烷的量较大 可以容易地制备超过95%的ee，以及(2)这些试剂 通过高度选择性的SE‘途径与醛缩合。值得注意的是 烯丙基锡烷发生Cram或络合控制加成反应 到α-手性醛，得到syn，syn；anti，syn；syn，anti；或 根据反应条件的不同，不同的反应条件也不同。这种反应是 据说对聚丙酸酯抗生素有潜在的应用 综合。首席调查员指出，拟议的路线是 简单和复杂的单糖是基于观察到的伽马- (烷氧基)烯丙基锡烷进行非对映和对映体选择性加成 给出单保护的高烯丙基1，2-二醇的醛 超过95%的光学纯度。他指出，用非外消旋的α-烷氧基 醛大大增强，实现了非对映选择性 通过试剂/底物匹配。这种方法论据说是 特别有吸引力，因为它允许准备 不同保护的5-10个碳的复合单糖 容易获得的手性池起始材料。值得注意的是，这样的 中间体是糖偶联物和低聚物的前体 潜在的抗生素和抗肿瘤特性。最终表明， 该方法也适用于α-氨基醛和 某些亚胺，从而允许合成各种生物上的 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.