1,3-dipolar cycloaddition reactions of nitrile oxides with 4,5-dihydrooxazole and 4,5-dihydrothiazole derivatives

Abstract

4,5-Dihydro-2-metyloxazole 1a and 4,5-dihydro-2,4,4-trimethyloxazole 1b, which are examples of cyclic imidate esters, undergo 1,3-dipolar cycloaddition reactions with benzonitrile N-oxide, to give the appropriate 5,6-dihydro-7a-methyl-3-phenyl-7a H-oxazolo[3,2- d]-1,2,4-oxadiazole ( 2a and 2b respectively). 4,5-Dihydro-2-methylthiazole 1c gives the thia analogue 2c. With alkanoyl and aroyl cyanide N-oxides (RCOCNO), 4,5-dihydro-2-methyloxazole 1a and 4,5-dihydro-2-methylthiazole 1c give the open-chain compounds, RCOXCH 2CH 2N(CN)COMe (X = O and S respectively).