M. Candan, E. Kendi, N. Gökhan
Jun 1, 2000
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Analytical Sciences
Abstract
benzoxazolinone, a number of derivatives have been tested for various activities, including anticonvulsant, antipyretic, analgesic, cardiotonic, antiulcer, or antibacterial, antimicrobial and antifungal effects. Numerous similar works are currently in progress to obtain a better understanding of the subject; it is clear that choosing a useful starting substance, such as acyl derivatives of benzoxazolinone, is the key step of the medicinal chemistry. The 6-acylbenzoxazolinones in particular exhibit analgesic properties that are much higher than those of the parent heterocycle, thus allowing the latest developments in the field of central nervous-system drugs. Although electrophilic substitution, such as chlorination, sulfonation and nitration, were achieved using classical reagents, acylation yielding 6-acyl derivatives were found to require particular conditions. The acylation of benzoxazolinone was accomplished earlier by two methods from the literature, in which either DMF-AlCl3 and acid chloride2 or polyphosphoric and carboxylic acids1 were used. It was reported that both methods gave the same product (6acylbenzoxazolinone) and almost the same yields.3 The title compound (I) (Fig. 1) was obtained and its structure analyzed by standard analytical techniques (UV, IR, NMR, mass spectroscopy and elemental analysis).4 In order to obtain information about the stereochemistry of the molecule and to confirm the assigned structure, an x-ray analysis of (I) was undertaken. 6-Acyl-2-benzoxazolinone was obtained by reacting 2benzoxazolinone with the appropriate carboxylic acid in polyphosphoric acid (PPA).1 To 2.5 mmol 6-acyl-4benzoxazolinone was added 7.5 mmol 2-vinylpyridine; the reaction mixture heated under reflux in an oil bath until molten, and then for 2 additional hours at 80 ̊C. By adding a cold alcohol–water mixture, the product separated; the resulting precipitate was collected by filtration. The crude product was recrystallized from an appropriate solvent. 671 ANALYTICAL SCIENCES JUNE 2000, VOL. 16 2000 © The Japan Society for Analytical Chemistry