Convenient Synthesis of Pyruvate Acetals of Carbohydrates by Coupling of Trialkylsilylated Diols and Pyruvates.

Abstract Hexopyranoside diols, mainly 4,6-diols with α- gluco , β- gluco , α- galacto , β- galacto , and α- manno configurations could be converted effectively (40 – 74% yields), to the corresponding pyruvate acetals by the coupling of the O -trialkylsilylated, namely. O -TBDMS and/or O -TMS diols, and ethyl pyruvate in the presence of TMSOTf at temperatures between −30 °C and +3 °C. In the case of β- manno isomer, the anomerization of the β-glycoside to the α-glycoside as well as the ring contraction of the pyranoside to the furanoside predominated.