Syntheses of 1,2-Unsaturated Cyclic Compounds and Related Derivatives

1 Syntheses of l Unsaturated Cyclic Compounds and Related Derivatives - 

An easy and efficient one pot synthesis of peracetylated glycals from unprotected sugars has been described. In this method the sugar was sequentially treated with acetic anhydride and catalytic hydrobromic acid-acetic acid (to effect per-acetylation), more hydrobromic acid-acetic acid (to form the glycosyl bromide), sodium acetate (to neutralize excess hydrobromic acid) and finally a buffered mixture of sodium acetate, acetic acid, zinc-copper sulfate and water (to effect a reductive-elimination). The method was applied to the syntheses of glycals derived from D-glucose, D-galactose, L-rhamnose, L-arabinose, maltose, lactose and maltotriose.  

Simply heating the 2-deoxy-sulfoxide 1 in benzene caused elimination of benzenesulfenic acid, producing the corresponding glycal in 98 % yield.  

Good yields of pyranoid glycals were obtained from acetal or ether protected D-gluco-, T)-galacto- or p-mamo- configured glycosyl sulfoxides by reaction with aryl- or alkyl-lithiums. It was determined that the nature of the lithium reagents 

Carbohydrate Chemistry, Volume 30 The Royal Society of Chemistry, 1998 

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