Remarkable Conversion of 2-Thioxo-2,3-dihydroquinazolin-4(1H)-ones into the Corresponding Quinazoline-2,4(1H,3H)-diones: Spectroscopic Analysis and X-Ray Crystallography

摘要

A simple and efficient new synthetic method to obtain 3-substituted quinazolin-2,4-diones 9 – 16 by the reaction of 3-substituted 2-thioxo-quinazolin-4-ones 1 – 8 with sodamide under mild conditions was presented. The structure of the newly synthesized compounds was determined by infrared spectroscopy, UV-visible spectroscopy, nuclear magnetic resonance, and single-crystal X-ray crystallographic analysis. The crystal structure of 6-methyl-3-phenylquinazoline-2,4(1H,3H)-dione ( 11 ) [C 15 H 12 N 2 O 2 : MF?=?252.27, triclinic, P-1, a ?=?7.8495 (13) ?, b ?=?12.456 (2) ?, c ?=?13.350 (2) ?, α ?=?103.322 (3)°, β ?=?90.002 (3)°, γ ?=?102.671 (4)°, V?=?1237.5 (3) ? 3 , Z ?=?4, R ?=?0.0592, wR?=?0.1699, S ?=?1.039] was determined. In the crystal cell, two identical conformers of compound 11 were found connected by intramolecular hydrogen bonds, responsible for the favourable occurrence of these two independent molecules.