Medium Size Ether Ring Formation of C-Alkynylated SugarsviaDicobalthexacarbonyl Complexes

All articles of this category Four C-alkynylated compounds at the C-1 position of D-glucal were converted into the corresponding dicobalthexacarbonyl complexes, which recyclized upon treatment with acid to form the medium size (7, 8, 9 and 10 membered) rings. Decomplexation was difficult under the usual oxidative condition, but it successfully worked under reductive condition in the presence of rhodium catalyst under high pressure hydrogen atmosphere.