Epoxy Glycals

The glycal epoxide method turned out to be useful for the construction of complex 2-branched [3-aryl glycosides, which are salient features of the potent antibiotic vancomycin [75a]. Glycal epoxide glycosylation with sodium salts of indoles pro- 

The final (3-glycosylation was carried out with fluoroglycoside 157 (R = Bz) to give, after deprotection, the desired natural compound [76c]. 

In a reiterative approach, enol ether epoxidation with DM DO has been coupled with C-C bond fonnation and ring-closing metathesis to provide trans-fused THP ring systems [82], 

A conceptually new direct oxidative glycosylation with glycal donors, employing a reagent combination of triflic anhydride and diphenyl sulfoxide, has recently been reported by Gin [83], This new 3-glycosylation method works very well with hindered hydroxy nucleophiles, including sterically shielded carbohydrate hydroxy systems, and can be run on large scales. 

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There are limited data on 1,2-epoxy of glycal epoxide ring opening reaction with C-nucleophiles other than organocuprate, e.g., Grignard reagents [217, 218], organolithium compounds [217-219], aUylstannane [217], and sodio di-tert-butyl malonate [219, 220]. 

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