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

Nucleophilic reaction of 5-amino- and 6-amino-2-substituted benzoxazoles 1 and 2 with 3-ethoxymethylene-2,4-pentanedione ( 3 ) gave compounds 5 and 6 . Compounds 1 and 2 reacted with ethyl ethoxymethylene-3-oxobutanoate ( 4 ) under formation of compounds 7 and 8 . The substitution products 7 and 8 underwent thermal cyclization at high temperature (boiling mixture of diphenyl ether and biphenyl) to give angularly and linearly 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 derivatives of 8-acetyl-9-oxo-oxazolo[5,4- f ]quinoline 11 and 6-acetyl-5-oxo-oxazolo[4,5- g ]quinoline 12 (from 8 ). The structure of the substitution products is discussed on the basis of their spectral characteristics ( 1 H and 13 C NMR, IR, UV, MS).