Boron trifluoride etherate → Methyl 4,7,8,9-tetra-O-acetyl-N-acetyl-2-S-[6-(5-cholesten-3beta-yloxy)hexyl]-2-thio-D-neuraminate

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Reaction Steps

Boron trifluoride etherate (700 μl, 5.5 mmol) is added to a solution of methyl 2,4,7,8,9-penta-O-acetyl-N-acetyl-D-neuraminate (1.01 g, 1.96 mmol) and 6-(5-cholesten-3β-yloxy)-hexane-1-thiol (0.98 g, 1.96 mmol) in dry chloroform (5 ml). The mixture is stirred under nitrogen for 5 hours at room temperature, and washed with aqueous sodium bicarbonate and water. The dried solution is concentrated to a residue which is put on a silica gel column and eluted with chloroform-ethyl ether-methanol (31:10:1). The β-anomer is isolated as a glass (400 mg), [α]D -38.5° (c 1.5, chloroform).

Provenance & Evidence