The [4+3] cycloaddition between furan and the oxyallyl cation generated from 2,4-dibromopentan-3-one resulted in the formation of 2alpha,4alpha-dimethyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (1). The catalytic oxidation of 1 with osmium tetraoxide and excess hydrogen peroxide resulted in the formation of acetonide 10. This was further converted into the alcohols 2, 11-15 with 23-86% yield. The alcohols 11-13 were treated with thionyl chloride in pyridine, forming their respective alkenes 17 (94%), 18 (89%) and 19 (80%). The herbicidal activity of the compounds was evaluated on the development of radicle of Sorghum bicolor L. and Cucumis sativus L., at the concentration of 100 and 250 ppm.
[4+3] cycloaddition; oxyallyl cation; herbicides
