The strategic use of para-quinone methides to access synthetically challenging and chemoselective α,α′-diarylmethyl N-glycosides from unprotected carbohydrate amines
Synthesis and Characterization of Novel Quinone Methides: Reference Electrophiles for the Construction of Nucleophilicity Scales
作者:Dorothea Richter、Nathalie Hampel、Thomas Singer、Armin R. Ofial、Herbert Mayr
DOI:10.1002/ejoc.200900299
日期:2009.7
acceptor substituted quinonemethides 2e–g. The second-order rate constants for the reactions of 3c–f and 2e–g with the carbanions 9a–h were determined photometrically in DMSO. With Equation (1), log k2 = s (N + E), and the known nucleophilicity parameters N and s for the carbanions 9a–h, it was possible to calculate the electrophilicity parameters E for these quinonemethides. With E parameters between
An Efficient One-Pot Protocol for Direct Access to Diarylmethyl Thioglycosides with para-Quinone Methides via S-Glycosyl Isothiouronium Salts
作者:Pintu Kumar Mandal、Atul Dubey
DOI:10.1055/s-0040-1707189
日期:2020.10
An efficientone-pot protocol has been developed for the direct preparation of diarylmethyl thioglycosides starting from per-O-acetylated sugars via glycosyl isothiouronium salts. The one-pot reaction conditions involve rapid conversion of the per-O-acetylated sugar with thiourea in the presence of boron trifluoride etherate as catalyst to give the corresponding glycosyl isothiouronium salt, which
The strategic use of <i>para</i>-quinone methides to access synthetically challenging and chemoselective α,α′-diarylmethyl <i>N</i>-glycosides from unprotected carbohydrate amines
A practical route to access synthetically challenging and chemoselective α,α′-diarylmethyl N-glycosides via Sc(OTf)3-catalyzed 1,6-conjugate addition of unprotected amino sugars with p-QMs.