Modified Koenigs-Knorr glycosidation

Alternate synthesis of the 2— 4-linked disaccharide J,. Upon glycosidation of 18 with the methyl ester-ketopyranosy 1 bromide under the modified Koenigs-Knorr conditions given for the synthesis of above, a 7 1 mixture of the B and o >-, 2— 4-linked disaccharide derivatives 19 and 20 was obtained in 27%... 

Paromamine, neamine, 4-0-(6-amino-6-deoxy- -D-glucopyranosyI)-2-deoxystreptamine, 5-0- (2-amino-2-deoxy-o-D-glucopyranosyl) -2-deoxy-streptamine, kasugamycin, and a,a-trehalosamine have been synthesized. A common feature in the structures of these antibiotics is the presence of an a-o-glycosidic linkage. In the total syntheses, modified Koenigs-Knorr reactions, or addition of nitrosyl chloride " to an enose, were successfully used. 

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