3,4-DIHYDRO-BENZ[1,3]OXAZINE DERIVATIVES FROM 2-ACYL(OR AROYL)-CYANATOBENZENES

3,4-Dihydro-2H-benz[1,3]oxazin-2-ones 3 are obtained from 2-acyl(or ar oyl)-cyanatobenzenes 2 and anisole. The reaction proceeds under Friede l-Crafts conditions via DIMROTH rearrangement. Compounds 2, dissolved in diethyl ether, react with 1 in the presence of finely powdered KOH at ambient temperature leading to 8. The structure of 8b is confirmed by X-ray structure analysis. (Z) - 4 -Ethylidene - 3,4-dihydro-2H-benz [1,3] oxazin-2-one 9 is formed upon treatment of 2-cyanatopropiopheno ne 2b with diluted hydrochloric acid. The ethylene derivative 5 is obt ained from 4 upon reaction with cyanogen bromide/triethyl amine.