A facile synthesis of 2-methyl-[3,4-di-O-acetyl-6-O-(chloroacetyl)-1,2-dideoxy-alpha-D-glucopyrano]-[2',1':4,5]-2-oxazoline.

The use of the chloroacetyl group as a protecting group has been studied for a 2-methylglyco-[2',1':4,5]-2-oxazoline. The reaction of chloroacetyl chloride or chloroacetic anhydride with 2-acetamido-1,3,4-tri-O-acetyl-2-deoxy-beta-D-glucopyranose provided 2-acetamido-1,3,4-tri-O-acetyl-6-O-(chloroacetyl)-2-deoxy-beta-D-glucopyranose which, on treatment with anhydrous ferric chloride in dichloromethane, produced the desired oxazoline. The glycosylating capability of the oxazoline has been investigated with aglycon hydroxides, to give the corresponding 2-acetamido-2-deoxy-beta-D-glucopyranosides. The chloroacetyl group can be selectively removed by treatment with thiourea, and migration of O-acetyl groups was not observed under these conditions.