Stereospecific, High-Yielding, and Green Synthesis of β-Glycosyl Esters

Abstract

A new method of synthesizing β-glycosyl esters stereospecifically has been developed by treating O-benzyl-protected glycosyl chlorides with Cs2CO3, tetrabutylammomium bromide (TBAB), a carboxylic acid, water, and granular polytetrafluoroethylene (PTFE) at 80 °C under mechanical agitation. D-Glucosyl, D-xylosyl, and D-galactosyl chlorides and 20 carboxylic acids were used to demonstrate the scope of the reaction. Control experiments showed that the water and granular PTFE had indispensable roles. Water-soluble TBAB has been found to be as efficient as N-methyl-N,N,N-trioctyloctan-1-ammonium chloride (Aliquat 336) in the reactions. After scaling up to 5-12 g, all of the products were obtained quantitatively via simple filtration and no organic solvents or chromatography was needed for the entire process.

Practical Glucosylations and Mannosylations Using Anomeric Benzoyloxy as a Leaving Group Activated by Sulfonium Ion

“…Crystalline β-glycosyl benzoate 1a , which can be prepared quantitatively according to our recently published method, was selected as the carbohydrate donor, and lauryl alcohol ( 2a ) was selected as the acceptor (Table ). Cyanuric chloride-activated dimethyl sulfoxide (DMSO) has been investigated as a precatalyst in several synthetic methods, − and it has been shown to have Lewis acid properties.…”

“…Commercially available reagents were used without further purification. The starting materials 1a , 1c–1o , − 2c , 2f , 2g , 2h , 2n–2o, and MeSCH 2 Cl were prepared according to the literature. 1 H NMR and 13 C NMR spectra were recorded with a 400 or 600 MHz spectrometer using tetramethylsilane (TMS) as an internal standard.…”

High-yielding aqueous synthesis of chloroacetophenones and aroyl chlorohydrins

“…Therefore, various methods have been developed to reduce the amount of volatile organic solvents such as solvent-free mechanical chemical conversions, [1][2][3][4][5][6][7] deep eutectic solvent-mediated reactions, 8 ionic liquid-mediated reactions [9][10][11][12][13] and aqueous reactions. [14][15][16][17][18][19][20][21][22] Our group has developed several types of aqueous reactions, [23][24][25][26] some of which perform even better than the conventional organic solventmediated reactions. For example, when organic solvents were replaced with water in aqueous Darzens reactions between haloketones and aldehydes, a quantitative yield of the pure product was obtained aer a simple ltration workup (i.e.…”

Diversion of a thioglycoligase for the synthesis of 1-O-acyl arabinofuranoses

“…Different synthetic strategies were therefore implemented to access such useful intermediates starting from either partially protected or unprotected sugar. Most popular methods relied on SN2 nucleophilic substitution of glycosyl halides 8,9 or trichloroacetimidate glycosides, 10 remote activation of methoxypyridyl glycoside, 11 Mitsunobu 12 or carbodiimide-promoted coupling 13 to yield either α-or β-glycosyl esters. Such strategies nevertheless lack either efficiency or selectivity.…”