Rh(II) Carbene-Mediated Synthesis of Methyl α- and β-Ketopyranosides: Preparation of Carbene Precursors, Quaternarization of the Anomeric Position, and Ring Opening of γ-Lactones
作者:Mélissa Boultadakis-Arapinis、Camille Lescot、Laurent Micouin、Thomas Lecourt
DOI:10.1080/07328303.2011.614983
日期:2011.9.1
Methyl alpha- and beta-ketopyranosides were efficiently prepared by carbene-mediated quaternarization of the anomeric position of corresponding aldopyranosides. Preparation of carbene precursors proved to be tedious and required a two-step procedure involving first bromoacetylation, followed by diazo-transfer with N,N'-ditosylhydrazine and DBU. Selective functionalization of the anomeric C-H bond was then achieved under Rh-2(OAc)(4) or Rh-2(acam)(4) catalysis. Finally, ring opening of the resulting gamma-lactones delivered alpha- and beta-ketopyranosides with the anomeric position functionalized by an independent chain.