GOULD-JACOBS REACTION OF 5-AMINO-2-SUBSTITUTEDAND 6-AMINO-2-SUBSTITUTED BENZOXAZOLES .2. REACTION WITH 3-ETHOXYMETHYLENE-2,4-PENTANEDIONE AND ETHYL 2-ETHOXYMETHYLENE-3-OXOBUTANOATE

Nucleophilic reaction of 5-amino- and 6-amino-2-sustituted benzoxazole s. 1 and 2 with 3-ethoxymethylene-2,4-pentenedione (3) gave compounds 5 and 6. Compounds 1 and 2 reacted with ethyl ethoxymethylene-3-oxobut anoate (4) under formation of compounds 7 and 8. The substitution prod ucts 7 and 8 underwent thermal cyclization at high temperature (boilin g mixture of diphenyl ether and biphenyl) to give angularly and linear ly annelated derivatives of 5-acetyl-4-oxo-oxazolo[4,5-f]-quinoline 9 and 7-acetyl-8-oxo-oxazolo[5,4-g]quinoline 10 (from 7), and derivative s of 8-acetyl-9-oxo-oxazolo[5,4-f]quinoline 11 and 6-acetyl-5-oxo-oxaz olo [4,5-g] quinoline 12 (from 8). The structure of the substitution p roducts is discussed on the basis of their spectral characteristics (H -1 and C-13 NMR, LR, UV, MS).