H. Krishnan, S. Κ. Chowdary, P. Dubey
2000
Citations
1
Influential Citations
6
Citations
Journal
Heterocyclic Communications
Abstract
2,3-dichloroquinoxaline 3 on reaction with alcohols in the presence of K : C 0 3 as base and TEBAC as phase transfer catalyst at RT gave 1:1 products, i.e. 2-chloro-3-alkoxyquinoxalines 4. In the presence of the same reagent but under refluxing conditions, 3 gave 1:2 products i.e. 2,3-dialkoxyquinoxalines 5. 2,3-dichloro-6-nitroquinoxaline 7 on treatment with various alcohols in the presence of K ; C 0 3 as base and TEBAC as phase transfer catalyst at 1 0 ° to -5°C gave the monoalkoxy derivatives of 7 i.e. 2-alkoxy-3-chloro-6-nitroquinoxalines 8 and at RT gave the dialkoxy derivative i.e. 2,3-dialkoxy-6-nitroquinoxaline 9. The structures of these 'compounds are supported by their spectral and analytical data and comparison with those known in literature. Introduction Quinoxaline derivatives and fused quinoxalines are reported to possess interesting pharmacological properties. In continuation of our studies on the synthesis of quinoxaline derivatives of potential biological activities, we have carried out studies on the reaction of 2,3-dichloroquinoxaline 3 with alcohols under different conditions leading to the formation of title mono and dialkoxyquinoxalines. These results are reported in this paper. Results and Discussion o-Phenylenediamine 1 was condensed with oxalic acid under Phillips' conditions to obtain quinoxaline-2,3-dione 2. The latter on treatment with POCl3 gave the previously reported 2,3-dichloroquinoxaline 3. With a view to prepare the monoalkoxy derivative of 3. the reaction of the latter with methanol in the presence of K.,C03 as base and triethylbenzylammonium chloride (TEBAC) as phase transfer catalyst at RT was carried out. On processing, the reaction mixture yielded a product, which was found to be homogeneous on tic and analyzed for a 1:1 composition. Its m.p. was found to be 74-76° C, different from starting material (i.e. 152-53° C). This compound was imagined to be 2-chloro-3-