Catalyst-Controlled Stereoselective <i>O</i>-Glycosylation: Pd(0) vs Pd(II)
作者:Hui Yao、Shasha Zhang、Wei-Lin Leng、Min-Li Leow、Shaohua Xiang、Jingxi He、Hongze Liao、Kim Le Mai Hoang、Xue-Wei Liu
DOI:10.1021/acscatal.7b01630
日期:2017.8.4
Stereoselective construction of various O-glycosidic bonds was first achieved by different palladium sources using 3,4-O-carbonate galactal as the donor to reach yields up to 95% under mild conditions. With Pd(II) catalyst coordination of this glycal donor from the β-face directed by carbonate group, hard nucleophiles (aliphatic alcohols) gave β-glycosides and α-glycosides were obtained from soft nucleophiles
Dissection of the effects that govern thioglucoside and thiomannoside reactivity
作者:Mads Heuckendorff、Lulu Teressa Poulsen、Christinne Hedberg、Henrik H. Jensen
DOI:10.1039/c7ob02968c
日期:——
Neighboringgroupeffects were investigated in gluco- and manno-configured thioglycosides under NIS/TfOH activation. Donors possessing a 2-O-benzoyl group that are capable (1,2-trans) and incapable (1,2-cis) of exerting nucleophilic push were compared with donors possessing a participatory neutral 2-O-benzyl group. By using competition experiments between sets of glycosyl donors the direct effect of