1-8H-pyrano[3,2-g]benzoxazol-8-ones from 7-methoxyimino-4-methylchromene-2,8-dione

Article abstract of DOI:10.1016/S0040-4020(01)91229-3

7-Methoxyimino-4-methylchromene-2,8-dione 3, easily prepared from the quinone 1 reacts thermally with methylaromatics 5(a-g), benzyl derivatives 13(a-c), halo derivatives 14(a-c) to give mainly oxazolocoumarins. Products 8(a-d) are obtained from 5(a-d), 13(a-c). Compound 9 is obtained from 5(a-c) and 13(a-c), compounds 15(a-c) are obtained from 14(a-c), the aminophenol 10 and coumarin 16 are obtained from 5f and 14c respectively, while coumarin 12 is obtained from 5g. The reaction of 3 with N-methyl-aniline and N,N-dimethylbenzylamine gives compound 10 and 8a respectively.