An efficient synthesis of 2,3-dihydro-1-H-pyrimido[1,2-a]quinoxaline 6-Oxides

MA. BEATRIZ GARCÍA; LILIANA R. ORELLI; MA. LAURA MAGRI; ISABEL A. PERILLO

SYNTHESIS-STUTTGART

Georg Thieme Verlag Stuttgart

Año: 2002 vol. 23 p. 2687 - 2690

0039-7881

5-Aryl 2,3-dihydro-1H-pyrimido[1,2a]quinoxaline 6-oxides 1a-f were synthesized with high yields (78-91%) by ring closure of N-acyl-N´-(o-nitroaryl)-1,3-propanediamines 2 with ethyl polyphosphate (PPE) to the corresponding 2-benzyl-1-(o-nitroaryl)-1,4,5,6-tetrahydropyrimidines 3, followed by spontaneous heterocyclization. 5-Alkyl (or aralkyl) derivatives derivatives were prepared by the same procedure. The method was extended to the synthesis of homologous 1,2,3,4-tetrahydro-6-phenyl-1,3-diazepino[1,2a]quinoxaline 7-oxide, a new type of condensed nitrogen heterocycle. Amidinoquinoxaline oxides are known to posess antimicrobial and antitumor properties.