Site- and Stereoselective C–H Alkylations of Carbohydrates Enabled by Cooperative Photoredox, Hydrogen Atom Transfer, and Organotin Catalysis
作者:Daniel J. Gorelik、Julia A. Turner、Tarunpreet S. Virk、Daniel A. Foucher、Mark S. Taylor
DOI:10.1021/acs.orglett.1c01718
日期:2021.7.2
carbohydrates with electron-deficientalkenes in the presence of an Ir(III) photoredox catalyst and quinuclidine, a hydrogen atom transfer mediator. Quantum-chemical calculations support a proposed mechanism involving the formation of a cyclic stannylene acetal intermediate that shows enhanced reactivity toward hydrogen atom abstraction by the quinuclidinium radical cation. Addition of the carbon-centered
Stereocontrolled Synthesis of <scp>d</scp>- and <scp>l</scp>-β-Rhamnopyranosides with 4-<i>O</i>-6-<i>S</i>-α-Cyanobenzylidene-Protected 6-Thiorhamnopyranosyl Thioglycosides
作者:David Crich、Linfeng Li
DOI:10.1021/jo8022439
日期:2009.1.16
The synthesis of both enantiomers of a 4-O-6-S-α-cyanobenzylidene-protected 6-thiorhamnopyranosyl thioglycoside is described starting from d-mannnose and l-arabinose derivatives for the d- and l-series, respectively. This donor is effective in the preparation of the corresponding β-glycosides using the 1-benzenesulfinyl piperidine/trifluoromethanesulfonic anhydride protocol. Following desulfurization