Synthesis and photoinitiated thiol–ene reactions of exo-mannals – a new route to C-β-d-mannosyl derivatives

Abstract

A synthetic procedure was elaborated for O-peracylated exo-mannals. Thiol-ene additions to pyranoid and furanoid exo-mannals gave mannosylmethyl sulfide type adducts with exclusive regio- and β(d)-stereoselectivities including disaccharide mimetics.

Stereoselective Synthesis of Ribofuranoid exo-Glycals by One-Pot Julia Olefination Using Ribofuranosyl Sulfones

“…A variety of reactions, such as the Julia olefination, Wittig reaction, methylenation with the Tebbe reagent or Petasis reagent, dihalomethylenation with tris­(dimethylamino)­phosphine or triphenylphosphine and carbon tetrahalide, as well as nucleophilic addition of organometallic compounds and subsequent dehydration, are used to synthesize exo -glycals from sugar lactones. Many other methods have been reported, such as the Ramberg–Bäcklund rearrangement of glycosyl sulfones, Wittig reaction with glycosyl phosphonium salts, Keck allylation of 1-bromoglycosyl chlorides and dehydrochlorination, Bamford–Stevens reaction, [2,3]-Wittig rearrangement of 1- C -alkenylglycosides, β-elimination reaction, Claisen rearrangement or S N 1′-type substitution of 1- C -vinylglycosides, and base-promoted alkynol cycloisomerization …”