scaffold has been a historical challenge. Here, we report a strategy that allows for the site-selective and site-divergent delivery of terminal propargyls to various monosaccharides, the basic units of carbohydrates. This strategy is based on synergistic catalysis that combines copper and borinic acid catalysis. With a pair of antipodal ligands, this method can be tuned to propargylate either the equatorial
A facile synthesis of per-O-alkylated glycono-δ-lactones from per-O-alkylated glycopyranosides and a novel ring contraction for pyranoses
作者:Matthias Goebel、Heinz-Georg Nothofer、Günther Roß、Ivar Ugi
DOI:10.1016/s0040-4020(97)00068-9
日期:1997.3
A novel one-pot synthesis of a variety of O-peralkylated δ-aldonolactones 9 from their corresponding glycosides 1 is introduced. This facile procedure involves combining glycoside precursor, tin(IV) chloride and trimethylsilyl azide in methylene chloride at room temperature to furnish the title compounds in moderate to high yields. A side reaction involving extrusion of C-1 of the common carbohydrate
Anomeric alkylations and acylations of unprotected mono- and disaccharides mediated by pyridoneimine in aqueous solutions
作者:Kalyan Dey、Narayanaswamy Jayaraman
DOI:10.1039/d1cc07056h
日期:——
A site-specific deprotonation followed by alkylations and acylations of sugar hemiacetals to the corresponding alkyl glycosides and acylated sugars in aqueoussolutions is disclosed herein. Pyridoneimine as a new base is developed to mediate the deprotonation of readily available sugar hemiacetals and further reactions with alkylation and acylation agents.
A synergistic Rh(I)/organoboron-catalysed site-selective carbohydrate functionalization that involves multiple stereocontrol
作者:V. U. Bhaskara Rao、Caiming Wang、Daniel P. Demarque、Corentin Grassin、Felix Otte、Christian Merten、Carsten Strohmann、Charles C. J. Loh
DOI:10.1038/s41557-022-01110-z
日期:2023.3
Particularly, exploiting chiral catalysis to control site selectivity in complex carbohydrate functionalizations has emerged as a leading method to unravel unprecedented routes into biologically relevant glycosides. However, robust catalytic systems available to overcome multiple facets of stereoselectivity challenges to this end still remain scarce. Here we report a synergistic chiral Rh(I)- and organoboron-catalysed
Arabinose as a chiral auxiliary for the asymmetric α-hydroxyallylation of aldehydes to syn-1,2-diols
作者:Jun-ichi Chika、Hisashi Takei
DOI:10.1016/s0040-4039(97)10656-6
日期:1998.2
In the presence of triethylaluminum, enantiomerically pure syn-1-substituted-butene-1,2-diol derivatives 4 are synthesized stereoselectively starting from allyl arabinopyranoside 3 and aldehydes. (C) 1998 Elsevier Science Ltd. All rights reserved.