Heating N-acyl derivatives 4 of 3-endo-aminobicyclo [2.2. l] hept-5-en-2-end0-01 (3) at 185- 195 OC for 4-5 h provides oxazoles la-in 49-8895 yields. The reaction proceeds via initial dehydration to an oxazoline which undergoes retro-Diels-Alder reaction to provide the oxazole. Similarly, imidazoles 7a-f may be obtained in 40-79% yields by heating imidazolines 6a-f to effect the cycloreversion.
