Gold(I)-Catalyzed Direct Stereoselective Synthesis of Deoxyglycosides from Glycals
作者:Carlos Palo-Nieto、Abhijit Sau、M. Carmen Galan
DOI:10.1021/jacs.7b08898
日期:2017.10.11
AgOTf enables the unprecedented direct and α-stereoselective catalytic synthesis of deoxyglycosides fromglycals. Mechanistic investigations suggest that the reaction proceeds via Au(I)-catalyzed hydrofunctionalization of the enol ether glycoside. The room temperature reaction is high yielding and amenable to a wide range of glycal donors and OH nucleophiles.
Stereoselective organocatalyzed glycosylations – thiouracil, thioureas and monothiophthalimide act as Brønsted acid catalysts at low loadings
作者:G. A. Bradshaw、A. C. Colgan、N. P. Allen、I. Pongener、M. B. Boland、Y. Ortin、E. M. McGarrigle
DOI:10.1039/c8sc02788a
日期:——
Thiouracil catalyzes stereoselective glycosylations with galactals in loadings as low as 0.1 mol%.
硫尿嘧啶在载体负载量低至0.1 mol%时,催化与半乳糖醛糖苷的立体选择性糖基化。
Cooperative Brønsted Acid-Type Organocatalysis for the Stereoselective Synthesis of Deoxyglycosides
作者:Carlos Palo-Nieto、Abhijit Sau、Ryan Williams、M. Carmen Galan
DOI:10.1021/acs.joc.6b02498
日期:2017.1.6
α-stereoselective synthesis of deoxyglycosides using cooperative Brønsted acid-type organocatalysis has been developed. The method is tolerant of a wide range of glycoside donors and acceptors, and its versatility is exemplified in the one-pot synthesis of a trisaccharide. Mechanistic studies suggest that thiourea-induced acid amplification of the chiral acid via H-bonding is key for the enhancement
devised a method for stereoselective O-glycosylation using an Ir(I)-catalyst which enables both hydroalkoxylation and nucleophilic substitution of glycals with varying substituents at the C3 position. In this transformation, 2-deoxy-α-O-glycosides were acquired when glycals equipped with a notoriously poor leaving group at C3 were used; in contrast 2,3-unsaturated-α-O-glycosides were produced from glycals
作者:Miao Liu、Zhao-Xiang Luo、Tian Li、De-Cai Xiong、Xin-Shan Ye
DOI:10.1021/acs.joc.1c01318
日期:2021.11.19
Carbohydrates play essential roles in various physiological and pathological processes. Trifluoromethylated compounds have wide applications in the field of medicinal chemistry. Herein, we report a practical and efficient trifluoromethylation of glycals by an electrochemical approach using CF3SO2Na as the trifluoromethyl source and MnBr2 as the redox mediator. A variety of trifluoromethylated glycals
碳水化合物在各种生理和病理过程中发挥着重要作用。三氟甲基化化合物在药物化学领域有着广泛的应用。在此,我们报道了一种使用CF 3 SO 2 Na 作为三氟甲基源和MnBr 2作为氧化还原介体的电化学方法对糖醛进行实用且有效的三氟甲基化。多种带有不同保护基团的三氟甲基化糖以 60-90% 的收率获得,具有高区域选择性。CF 3自由基的成功捕获表明该反应涉及自由基机理。