Direct, microwave-assisted substitution of anomeric nitrate-esters

Intramolecular Metal-Free C(sp3)-H Activation Enables a Selective Mono O-Debenzylation of Fully Protected Aminosugars

“…Following the hydrogenation general procedure, methyl 2-azido-3,4,6-tri- O -benzyl-2-deoxy-α- d -galactopyranoside S 2 (200 mg, 0.41 mmol) afforded, after 16 h, compounds 3 and 4 (188 mg, 0.33 mmol, 81%) as an equimolecular mixture easily separable by column chromatography (hexanes–EtOAc, 80:20). Compound 3 : Colorless oil.…”

“…Methyl 3,4,amino-2deoxy-α-D-galactopyranoside (3) and Methyl 3,4,6-tri-O-Benzyl-2-(tert-butoxycarbonyl)amino-2-deoxy-β-D-galactopyranoside(4). Following the hydrogenation general procedure, methyl 2-azido-3,4,6-tri-O-benzyl-2-deoxy-α-D-galactopyranoside S219 (200 mg, 0.41 mmol) afforded, after 16 h, compounds 3 and 4 (188 mg, 0.33 mmol, 81%) as an equimolecular mixture easily separable by column chromatography 80:20). Compound 3: Colorless oil.…”

Investigation of Glycosyl Nitrates as Building Blocks for Chemical Glycosylation

“…[20] Glycosyl nitrates have been known for years, but their application was limited to their use as precursors for other leaving groups after azidonitration reaction of glycals. [21,22] Another, less known application, is the synthesis of 1,2-orthoesters. [23] However, glycosyl nitrates have never been O -glycosidated beyond the synthesis of aliphatic glycosides of amino sugars with charged nucleophiles [24,25] or under microwave irradiation conditions.…”

“…[23] However, glycosyl nitrates have never been O -glycosidated beyond the synthesis of aliphatic glycosides of amino sugars with charged nucleophiles [24,25] or under microwave irradiation conditions. [22] The ability to form 2-OH glucose from glycosyl nitrates without additional reagents implies that the anomeric nitro group can act as a suitable leaving group in glycosylation. Reported herein is our first attempt to study glycosyl nitrates as glycosyl donors in chemical glycosylation reactions with a variety of sugar alcohols as glycosyl acceptors.…”

One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates

“…The process involves a two reaction, one-pot procedure from 2-azido-1-nitrate esters. 21 This detailed protocol is intended to assist practitioners in successfully completing the transformation in high yield. Of particular interest is the first step of the sequence, which focuses on thermal denitration under microwaveassisted heating.…”