Trichloroacetonitrile → 2,3,4,6-tetra-O-benzoyl-alpha-D-mannopyranosyl-(1->3)-2,4,6-tri-O-benzoyl-alpha-D-mannopyranosyl-(1->3)-2,4,6-tri-O-benzoyl-D-mannopyranosyl trichloroacetimidate

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Reaction Conditions

Reaction Steps

The hemiacetal 52 (330 mg, 0.214 mmol) was dissolved in anhydrous DCM (1.1 mL, 0.2 M). To the solution was added trichloroacetonitrile (43 μL, 0.427 mmol, 2 eq). The mixture was stirred at 0° C. while a solution of DBU (1.6 μL, 0.05 eq, 0.0107 mmol) in anhydrous DCM (0.15 mL) was added. The mixture was stirred at 0° C. for 4 h and TLC (hexane-EtOAc=65:35) indicated the complete conversion. The crude was evaporated onto silica gel and purified by silica column chromatography (2×14 cm, gradient elution with hexane-EtOAc 200:20, 150:30, 120:30, 150:50 and hexane-EtOAc-Et3N 140:70:0.3) to give the trichloroacetimidate 53 as white foam (261 mg, 72%) which was used directly in the next step without further characterization.

Provenance & Evidence