X-ray mapping in heterocyclic design: VI. X-ray diffraction study of 3-(isonicotinoyl)-2-oxooxazolo[3,2-a]pyridine and the product of its hydrolysis
Rybakov VB, Babaev EV, Pasichnichenko KY, Sonneveld EJ
CRYSTALLOGRAPHY REPORTS 47 (1): 69-74 JAN-FEB 2002

Abstract:
The structure of 3-(isonicotinoyl)-2-oxooxazolo[3,2-a]pyridine, C13H8N2O3, (1) is determined by X-ray powder diffraction analysis. Crystals I are orthorhombic, a = 16.610(2) Angstrom, b = 3.853(1) Angstrom, c = 16.431(2) Angstrom, Z = 4, and space group Pna2(1). The structure is solved by the grid search procedure and refined by the Reitveld method (R-p = 0.086, R-wp = 0.115, R-e = 0.030, and chi(2) = 11.138). The structure of the product of hydrolysis of compound I, C12H10N2O2, (II) is determined by the single-crystal X-ray diffraction technique. Crystals II are orthorhombic, a = 8.755(4) Angstrom, b = 10.526(17) Angstrom, c = 23.088(6) Angstrom, Z = 8, and space group Pc2(1)b. The structure is solved by the direct method and refined by the full-matrix least-squares procedure to R = 0.0464. A fragment of two fused heterocycles in I is planar. The dihedral angle between the plane of the pyridine ring in the isonicotinoyl fragment and the plane of the bicyclic system is 51.2(2)degrees. Both exocyclic CO groups that are adjacent to the five-membered fragment contain double bonds. The structures of two crystallographically independent molecules II are almost identical to each other, and the isonicotinoyl fragment is nearly perpendicular to the plane of the pyridone fragment [84.3(1)degrees and 87.0(1)degrees]. (C) 2002 MAIK "Nauka/Interperiodica".