Collect. Czech. Chem. Commun. 1996, 61, 371-380

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

Katarína Heleyováa, Dušan Ilavskýb, Vladimír Bobošíkb and Naďa Prónayovác

a Research Institute for Drugs, 900 01 Modra, Slovak Republic
b Department of Organic Chemistry, Slovak Technical University, 812 37 Bratislava, Slovak Republic
c Central Laboratory, Slovak Technical University, 812 37 Bratislava, Slovak Republic


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 7and 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 (1H and 13C NMR, IR, UV, MS).

Keywords: Gould-Jacobs reaction; Oxazoloquinolones.