Stereoselective α-glycosidation using FeCl3 as a Lewis acid catalyst

Highly Efficient Deacetylation by Use of the Neutral Organotin Catalyst [tBu2SnOH(Cl)]2

“…The crude product was subjected to a column chromatography on silica gel to give pure 1,2,3,4-tetra-O-acetyl-a-d-glucose [29] in 88 % yield. The deacetylated products obtained by treatment of 31, [29] 32, [30] 34, [31] 35, [29] 36, [32] 37, [33] and 41 [34] with methanol in the presence of catalyst 1 are reported previously, and the deacetylated pyranose derived from 33 is a commercially available. Deacetylation of cytidine tetraacetate (43) and the subsequent pivalation (Representative procedure): Tetraacetate 43 (411 mg, 1.0 mmol), 1 (28.5 mg, 0.05 mmol), THF (5 mL), and methanol (5 mL) were added to a round-bottomed flask, and the mixture was stirred at 30 8C for 24 h. After addition of CH 2 Cl 2 , the reaction mixture was filtered through a thin pad of silica gel, and the filtrate was concentrated to give a crude product of 2,3-di-O-acetylcytidine.…”

A Straightforward Synthesis of 1‐Adamantylmethyl Glycosides, and Their Binding to Cyclodextrins

“…The α-anomer was obtained by in situ anomerization of the initially formed β-anomer. [12] Control over the anomerization step, however, should lead to α/β mixtures depending on the anomerization conditions. [13] Classical glycosidation methods demand both selective activation of the anomeric centre and differently protected monosaccharides for obtaining each anomer.…”

Formation of the Glycosidic Linkage

“…When this ester is present at the anomeric position, it presents a way of activating the molecule, with the aid of a Lewis acid, into an effective glycosyl donor: 75 Glycosyl acetates should be considered as cheap and effective glycosyl donors and certainly one of the first 'off-the-shelf' choices (often in combination with boron trifluoride diethyl etherate): [76][77][78] Other sorts of esters have seen increasing use as glycosyl donors, including xanthates (O-alkyl S-glycosyl dithiocarbonates), 7,79-81 phosphites 82-88 and phosphates: [89][90][91] When this ester is present at the anomeric position, it presents a way of activating the molecule, with the aid of a Lewis acid, into an effective glycosyl donor: 75 Glycosyl acetates should be considered as cheap and effective glycosyl donors and certainly one of the first 'off-the-shelf' choices (often in combination with boron trifluoride diethyl etherate): [76][77][78] Other sorts of esters have seen increasing use as glycosyl donors, including xanthates (O-alkyl S-glycosyl dithiocarbonates), 7,79-81 phosphites 82-88 and phosphates: [89][90][91] …”