(1R,2S,4R)-2-benzyloxy-4-methoxy-5-(1-methylethyl)-6,8-dioxabicyclo[3.2.1]octane and (1R,2S,4R)-2-benzyloxy-4-methoxy-2-methyl-6,8-dioxabicyclo[3.2.1]octane

The title compounds, C17H24O4 and C15H20O4, respectively, were obtained during studies of the relationship between structure and herbicidal activity of derivatives of levoglucosenone [Furneax et al. (1989). European Patent Application 0 302 599; Furneaux, Henzell & Tyler (1991). US Patent 5 047 518; Blattner, Furneaux, Mason & Tyler (1991). Pestic. Sci. 31, 419-435; Furneaux, Mason & Tyler (1995). Unpublished results]. The crystal structures contain independent molecules held together by van der Waals packing forces. The pendant groups at Cl in C17H24O4 have a minor effect on the fused dioxolane-pyranose ring conformation. The O-benzyl groups adopt different conformations determined by minimization of intramolecular repulsive contacts, particularly for the 4-C-methyl molecule, and intermolecular non-bonding contacts.