A diastereoselective, metal-free, one-pot domino synthetic strategy was developed for the transformation of glycals into new chiral scaffolds. Optimization of the reaction conditions to exclude normal Ferrier products, characterization of the new entities, and a plausible mechanism were investigated.
A highly stereoselective rapid C-glycosylation reaction has been developed between glycal and unactivated alkynes in the presence of coppertriflate and ascorbic acid at low catalyst loading and at room temperature. A wide variety of glycals and aryl acetylenes participate in the reaction smoothly. TfOH generated during the reduction of Cu(OTf)2 by ascorbic acid may be the active catalyst for the glycosylation.
Tris(pentafluorophenyl)borane-Catalyzed Stereoselective C-Glycosylation of Glycals: A Facile Synthesis of Allyl and Alkynyl Glycosides
作者:Pintu Kumar Mandal、Anand Gaurav、Zanjila Azeem
DOI:10.1055/a-2186-7116
日期:2024.3
features a broad functional group tolerance including a variety of glycals coupled with allyltrimethylsilane and trimethylsilylphenylacetylene to access the corresponding 2,3-unsaturated allyl- and alkynyl-C-glycosides with excellent α-selectivity. The reaction proceeds in good to excellent yields via concomitant borane activation of glycal donor under mild conditions.
在现代发展中,三(五氟苯基)硼烷(通常称为 BCF)催化剂因其在多种有机反应中的广泛用途而受到重视。通过在温和反应条件下使用催化量的B(C 6 F 5 ) 3生成2,3-不饱和C-糖苷,提出了一种有效且高度立体选择性的α- C-糖基化策略。该反应具有广泛的官能团耐受性,包括多种糖醛与烯丙基三甲基硅烷和三甲基甲硅烷基苯乙炔偶联,以优异的α-选择性获得相应的2,3-不饱和烯丙基-和炔基-C-糖苷。通过在温和条件下伴随硼烷活化糖醛供体,该反应以良好至优异的产率进行。