Synthesis of Delta(2)-isoxazoline fatty acid ester heterocycles

Fatty ester Delta (2)-isoxazoline heterocycles were prepared in good yields and excellent regioselectivity from 1,3-dipolar cycloaddition reactions be tween methyl 10-undecenoate and nitrile oxides. This methodology provides c onvenient access to the methyl esters of margaric (4b) and stearic (4c) aci ds in 63-66% yield that contain the isoxazoline heterocycle between C-10 an d C-12. These fatty heterocycle compounds are synthesized in a one-pot sequ ence in which methyl 10-undecenoate is used to trap the reactive nitrile ox ide intermediates that are generated by reacting aldoximes with aqueous sod ium hypochlorite and a catalytic amount of triethylamine or by directly rea cting hydroximic acid chlorides with a stoichiometric amount of base. The f atty ester Delta (2)-isoxazoline heterocycles represent a versatile synthon that may be useful to obtain oleochemicals with potentially new and intere sting properties not easily accessible by other methods.