Reaction of monosaccharaide derivatives with stabilized sulfur ylides. A highly stereoselective synthesis for C-glycofuranosides
摘要:
Stereoselectivity in the formation of glycidic amides by reaction of various aldehydo- and keto-sugars [(1), (4), (6), (8), (10) and (12)] with N,N-dimethyl-2-(dimethylsulfuranylidene)acetamide (2) was studied. The reaction with derivatives of reducing cyclohemiacetalic monosaccharides (14) and (21), gives to alpha-C-glycofuranosyl-2(S)-hydroxyacetamides with a higher yield and stereoselectivity.
A new type of chiral sulfoniumsalts that are characterized by a bicyclic system has been designed and synthesized from α‐amino acids. Their corresponding ylides, which were prepared by basic treatment of the sulfoniumsalts, reacted smoothly with a broad array of simple and chiral aldehydes to provide trans‐epoxy amides in reasonable to very good yields and excellent stereoselectivities (>98 %). The
chiral sulfonium salts, derived fromL- and D-methionine, has been designed and successfully employed in our laboratories for the diastereoselective synthesis of glycidic amides. The epoxy amides obtained were converted cleanly into 1,2-difunctionalized products through oxirane ring-opening reactions with different types of nucleophiles. The resulting ring-opened products represent valuable and useful
一类新的手性锍盐衍生自 L- 和 D-甲硫氨酸,已被设计并成功用于我们实验室的缩水甘油酰胺的非对映选择性合成。获得的环氧酰胺通过与不同类型亲核试剂的环氧乙烷开环反应完全转化为 1,2-双官能化产物。由此产生的开环产品代表了合成不同生物活性产品的有价值和有用的构建模块。因此,已经实现了克拉维醇 H 的便利合成以及其他生物活性化合物的关键前体的合成,例如聚酮衍生的天然产物,证明了这种化学的合成效率和实用性。
Epoxyamide-Based Strategy for the Synthesis of Polypropionate-Type Frameworks
作者:Francisco Sarabia、Francisca Martín-Gálvez、Miguel García-Castro、Samy Chammaa、Antonio Sánchez-Ruiz、José F. Tejón-Blanco
DOI:10.1021/jo801728s
日期:2008.11.21
A new approach to the stereoselectivesynthesis of polypropionate-type frameworks is reported utilizing reactions of amide-stabilized sulfur ylides with chiral aldehydes. To establish a new strategy for macrolide fragmentsynthesis, the stereoselectivity of these reactions in the construction of epoxy amides was the most important aspect of this study. In this aspect, we found a strong influence of
3]-sigmatropic rearrangement involving stabilized sulfur ylides and allenoates has been thoroughly established. The scope and utility of this reaction have been extensively studied resulting in C–C bond formation under mild conditions with greater than 20 examples reported. A highlight of the work is the simple and fully operational process that does not involve the use of carbenes or the associated hazardous
The synthesis of the polypropionate chain of Streptovaricin U (1) is described utilizing a new approach for the stereoselective synthesis of the macrolide-type antibiotics via sulfur ylides.