Thiogalactosyl donors

In situ preactivation of thioglycosides with BSP/Tf20, initially developed by Crich for the synthesis of /i-mannosides 21 was applied to expeditious oligosaccharide synthesis by van der Marel and co-workers.20 For a representative example, see the synthesis110 of 106 depicted in Scheme 19. The thiogalactosyl donor 102 was preactivated with BSP/Tf20 and then allowed to react with thiomannoside 103 to yield disaccharide 104 in 73% yield. The latter then reacted with glycosyl acceptor... 

Table 2 Influence of positions of the benzoyl group over the hydroxyl group on the reactivity of thiogalactosyl donors...

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