2-BENZYLOXY-6,8-DIOXABICYCLO[3.2.1]OCTANES - NEW CARBOHYDRATE-DERIVED HERBICIDES

Structure-activity relationships in a new group of 'cyclic ether' herbicides have been probed by synthesis and evaluation of a range of isomers and analogues of 1,6-anhydro-4-O-benzyl-3-deoxy-2-O-methyl-beta-D-glucopyranose. The absolute and relative stereochemical arrangement of the benzyloxy- and methoxy-groups and the pyran-ring oxygen atom possessed by this compound were essential for herbicidal activity, but the directionality of the -CH2O- bridge unit was not. The benzyl substituent could be modified, especially by ortho-substitution on the benzene ring, without significant loss of herbicidal activity, but the azido-, ethoxy- and allyloxy-groups were the only replacements for the methoxy-group that did not result in a significant loss of potency. Selectivity for weeds in broad-leaf crops was enhanced by the introduction of an alkyl or substituted alkyl group at the anomeric carbon.