Rhodium(II) catalyzed asymmetric cyclopropanation of glycals with ethyl diazoacetate
摘要:
Carbenoid species generated from ethyl diazoacetate and catalytic Rh-2(OAc)(4) react smoothly and with a high degree of stereoselectivity with glycals resulting in the predominant formation of doubly branched adducts containing an alpha-exo-orientated ethyl cyclopropanecarboxylate moiety.
Light-Mediated Cross-Coupling of Anomeric Trifluoroborates
作者:Eric M. Miller、Maciej A. Walczak
DOI:10.1021/acs.orglett.1c01035
日期:2021.6.4
Stereoselective reactions at the anomeric carbon constitute the cornerstone of preparative carbohydrate chemistry. Here, we report stereoselective C-arylation and etherification reactions of anomeric trifluoroborates derived from BMIDA esters. These reactions are characterized by high anomeric selectivities for 2-deoxysugars and broad substrate scope (24 examples), including disaccharides and trifluoroborates
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。
Catalytic and Photochemical Strategies to Stabilized Radicals Based on Anomeric Nucleophiles
作者:Feng Zhu、Shuo-qing Zhang、Zhenhao Chen、Jinyan Rui、Xin Hong、Maciej A. Walczak
DOI:10.1021/jacs.0c03298
日期:2020.6.24
metal-free conditions where a disulfide initiator can be activated by a Lewis base additive. Both strategies utilize anomeric nucleophiles as efficient radical donors and achieve a switch from an ionic to a radical pathway. Taken together, the stability of glycosyl nucleophiles, a broad substrate scope, and high anomer-ic selectivities observed for the thermal and photochemical protocols make this novel
A palladium-catalyzed direct C–H functionalization of glycals with cycloalkenones is described and a series of C-2functionalized glycals were synthesized efficiently with cyclic enones. The direct C–H functionalization of glycals with Pd(II) and subsequent insertion of cyclic enones via β-hydride elimination is the key to the synthesis of 2C-branched glycals. The synthetic utility of this methodology
<scp>C‐Aryl</scp> Glycosylation via Interrupted Pummerer Rearrangement<sup>†</sup>
作者:Jiagen Li、Xuefeng Jiang
DOI:10.1002/cjoc.202300308
日期:2023.11
enzymes. Herein, C-aryl glycosylation was established for the synthesis of 2-sulfur C-aryl glycals and 1,2-dihydrobenzofuran-fused C-aryl glycosides via interrupted Pummerer process, featured with sulfonium-tethered [3,3]-sigmatropic rearrangement between sulfoxide glycals and phenols. This protocol offers a broad substrate scope with diverse glycosyl and phenols. Dapagliflozin, Empagliflozin, and Ipragliflozin