Reactions of Some Pyranoside Diol Monotriflates with Nucleophiles and Bases

Article abstract of DOI:10.1021/jo00052a058

Reaction of pyranoside diol (equatorial) monotriflates with soft, nonbasic nucleophiles is a useful way to make axial heteroatom-substituted and "epimerized" pyranosides, particularly where a fused acetal ring inhibits ring contraction.Among the substrates examined (1,2,3,4,35), only 4 shows a strong tendency to give ring-contracted products.The reaction of 1-3 with more basic nucleophiles (F(1-), t-BuO(1-)) leads to the anhydrosugars 8, 25, and 26, respectively.The S_N2 reaction of 35 with tetra n-butylammonium iodide forms the basis for a new synthesis of the Cerny epoxide 32.