O-Glucosyl trichloroacetimidates

To our knowledge, only one attempt has been made toward the preparation and use of a fixed glucosyl trichloroacetimidate.9 Takahashi et al. described the synthesis of an attached O-glucosyl trichloroacetimidate and extended the use of the well known traceless silyl linker strategy (Scheme 4.11). 

A known method [221] for the preparation of C-glycosyl cyanides from tri-chloroacetimidates has been applied to the reaction of the 0-acetyl-protected O-glucosyl trichloroacetimidate [222, 223], Reaction with trimethylsilyl cyanide gave the a-glycoside, a valuable intermediate in the synthesis of carboxylic acid derivatives or other C-glycosides, in quantitative yield. 

The first total synthesis of simmondsin (73) a naturally occurring cyanoglucoside has been achieved from L-quebrachitoI and D-glucose. The key steps involve the deoxygenation of epoxide (74) with lithium aluminium hydride, cyanomethylation of the ketone (75) by Homer-Emmons alkenylation (with separation of Z and E isomers) and glycosidation of alcohol (76) with 2,3,4,6-tetra-O-acetyl-P-D-glucosyl trichloroacetimidate. 

Disaccharides ending in pentose units include a fully substituted 2-0-a-D-ribofuranosyl-L-rhamnose derivative produced from a glucosyl acetate or glycosyl trichloroacetimidate. 2,3,5-T ri-O-benzoyl-a-L-arabinofuranosyl chloride... 

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