A 2,4-O-[(Z)-2-butenylene]-bridged glucopyranose: efficient construction of the bicyclic skeleton and its axial-rich twist-boat conformation

Synthesis and conformational analyses of 1-O-acetyl-3,6-di-O-benzyl-2,4-O-[(Z)-2-butenylene]-β-d-glucopyranose are described. The construction of the trioxabicyclo[6.3.1]dodecane skeleton of the compound was initiated from a ring-opened glucose, followed by the successive cyclization of first the nine-membered ring and then the six-membered ring. The pyranose of the compound was in 3S1, an axial-rich twist-boat conformation. This result demonstrated an alternative method for the restriction of the pyranose into the axial-rich twist-boat conformation in contrast to the procedures that use bulky silyl protecting groups.