Synthesis of substituted benzoxazolinones by the curtius rearrangement: Crystal structures of Intermediates and by-products

Abstract

3-Substituted salicyloyl chlorides were converted to salicyloyl azides (R = Br, NO2) which underwent thermal rearrangement and intramolecular cyclization to benzoxazolinones. The crystal structures of 7-substituted benz[d]oxazolin-2-ones (R = Br, NH2), intermediate salicyloyl azides and by products, i.e. 3-(2-hydroxy-3-nitrophenyl)-8-nitrobenz[e][1,3]oxazine-2, 4-dione and 2-hydroxy-V- (2-hydroxy-3-nitrophenyl)-3-nitrobenzamide, have been determined. 7-Aminobenzoxazolinone was obtained by catalytic hydrogenation of the nitro compound as the hemihydrate or in anhydrous form, depending on the temperature of the crystallization. © 2011 Verlag der Zeitschrift für Naturforschung.