Selenoglycosides preparation

Selenoglycosides of sialic acid have been successfully prepared in excellent yields from the corresponding peracetylated glycosyl chloride with phenylselenol in the presence of N,N-di-isopropylethylamine [519]. This reagent combination succeeded where others were less effective or failed (Scheme 4.98 [520]. 

Photochemical oxidation has been employed for the activation of O-glycosides [552], thioglycosides [553] and telluroglycosides [554], It is also effective for O-glycosylation with the phenyl selenoglycoside donors [555], although this approach has not been widely taken up for preparative use. 

Typical Procedure for the Preparation of Selenoglycosides from Clycosyl Bromides... 

Mehta S, Pinto M. Phenyl selenoglycosides as versatile glycosylation agents in oligosaccharide synthesis and the chemical synthesis of disaccharides containing sulfur and selenium. In Hanessian S ed.. Preparative Carbohydrate Chemistry. New York Marcel Dekker, Inc., 1997 10 129. 

Another useful method for the preparation of phenyl selenoglycosides is the azidoselenation reaction, in which a glycal is reacted with sodium azide, diphenyldiselenide and (diacetoxyiodo)benzene to give a 2-azido-2-deoxy-seleno-glycoside. The reaction is believed to proceed through a radical mechanism, and... 

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