Mahata, P. K. ; Venkatesh, C. ; Kumar, U. K. Syam ; Ila, H. ; Junjappa, H. (2003) Reaction of α-oxoketene-N,S-arylaminoacetals with vilsmeier reagents: an efficient route to highly functionalized quinolines and their benzo/hetero-fused analogue Journal of Organic Chemistry, 68 (10). pp. 3966-3975. ISSN 0022-3263
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Official URL: http://pubs.acs.org/doi/abs/10.1021/jo034053l
Related URL: http://dx.doi.org/10.1021/jo034053l
Abstract
A simple, highly efficient, and regioselective synthesis of functionalized quinolines through Vilsmeier cyclization of a variety of α-oxoketene-N,S-anilinoacetals has been reported. The cyclization is found to be facile with N,S-acetals bearing strongly activating groups on aniline, whereas yields of quinolines are moderate in other cases. The reaction could also be extended for the synthesis of substituted tricyclic benzo[h]quinoline, pyrido[2,3-h]quinoline, 4,7-diphenylphenanthroline, and tetracyclic quino[8,7-h]quinoline by performing a Vilsmeier reaction on N,S-acetals derived from 1-naphthylamine, m-phenylenediamine, o-phenylenediamine, and 1,5-diaminonaphthalene, respectively. A few of the newly synthesized quinolines are subjected to further transformation to afford 2-unsubstituted (Raney-Ni/Ethanol), quinoline-5,8-quinone (NBS/H2SO4), or 2-alkyl/aryl aminoquinolines through sequential m-CPBA oxidation to the corresponding (2-methylsulfonyl)quinoline followed by replacement with appropriate amines. Similarly, cycloannulation of a few 2-methylthio-3-benzoylquinolines with hydrazine hydrate under microwave irradiation afforded the corresponding substituted and fused pyrazolo[3,4-b]quinolines in excellent yields, whereas TBTH/AIBN-mediated cyclization of the corresponding 3-(2-bromobenzoyl)-2-methylthioquinolines yielded the corresponding benzothiopyrano-fused quinolines through radical translocation.
Item Type: | Article |
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Source: | Copyright of this article belongs to American Chemical Society. |
ID Code: | 15271 |
Deposited On: | 13 Nov 2010 13:01 |
Last Modified: | 03 Jun 2011 09:15 |
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