940 Synthesis of {2-Oxo(thioxo)-3,4-dihydro-2H-1,3-benzoxazin- 4- yl}(thio)ureas and Their Derivatives M. M. Kurbanova Baku State University, ul. Z.Khalilova 23, Baku, AZ-1073, Azerbaijan e-mail: kurbanova1972@rambler.ru Received May 17, 2012 SHORT COMMUNICATIONS Synthesis of natural and biologically active hetero- cyclic compounds is an important problem of organic and medicinal chemistry. Oxazine derivatives were found to be efficient medicines exhibiting high cyto- static, antibacterial, and antiviral activity [1]; some compounds showed pronounced fungicidal and hypo- tensive effects [2]. These findings have stimulated research in the field of oxazine heterocycles, develop- ment of efficient methods for their preparation, and thorough study of their structure and chemical trans- formations with a view to define their role and place among other heterocycles. However, some oxazine derivatives remain poorly studied up to now; in partic- ular, this applies to {2-oxo(thioxo)-3,4-dihydro-2H- 1,3-benzoxazin-4-yl}(thio)ureas and their derivatives, though these compounds attract interest from the viewpoints of synthetic and theoretical chemistry and design of new efficient medicinal substances. The condensation of salicylaldehyde with urea in the presence of HCl was reported to produce 1,1'-[(2-hydroxyphenyl)methylene]diurea [3]. I syn- thesized (2-oxo-3,4-dihydro-2H-1,3-benzoxazin-4-yl)- urea (I) by reaction of salicylaldehyde with urea in acetonitrile. Likewise, (6-bromo-2-oxo-3,4-dihydro- 2H-1,3-benzoxazin-4-yl)urea (II) was synthesized by analogous condensation of 5-bromosalicylaldehyde (Scheme 1). Compounds I and II were isolated as crystalline substances whose structure was confirmed by NMR and IR spectroscopy and X-ray analysis of a single crystal of I (see figure) [4]. The ureido substit- uent in the oxazine ring of I occupies axial position; the torsion angle C 9 N 2 C 2 N 1 is –64.31(15)°, and the N 1 C 2 N 2 bond angle is 112.46(11)°]. The N 1 atom deviates by 0.2674 Å from the plane formed by the other atoms constituting the oxazine ring, which is due to formation of intermolecular hydrogen bond between the N 1 H proton and O 2 of the other molecule. The sum of the bond angles at the N 1 atom is 352.7°, and the torsion angle C 2 N 1 O 1 C 1 is 22.4(2)°. Crystalline com- pound I is a racemate (molecule I possesses one asym- metric center, C 2 ). Molecules I in crystal form zigzag layers parallel to the 0yz plane via intermolecular hydrogen bonds involving solvation water molecule as well. According to the data of [5], the condensation of salicylaldehyde with thiourea in methanol yields (1E,3E)-1,3-bis(2-hydroxybenzylidene)thiourea [5]. I carried out the reaction with the same reactants in acetonitrile and obtained (2-thioxo-3,4-dihydro-2H- 1,3-benzoxazin-4-yl)thiourea ( III ). (6-Bromo-2- ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 6, pp. 940–942. © Pleiades Publishing, Ltd., 2013. Original Russian Text © M.M. Kurbanova, 2013, published in Zhurnal Organicheskoi Khimii, 2013, Vol. 49, No. 6, pp. 953–955. DOI: 10.1134/S1070428013060274 I, R = H; II, R = Br. CHO OH (H 2 N) 2 C=O, MeCN OH N H OH NH 2 O (H 2 N) 2 C=O –H 2 O, –NH 3 O NH O HN NH 2 O I, II R R R Scheme 1.