Preparation, Reactivity and Tautomeric Preferences of Novel (1H-Quinolin-2-ylidene)propan-2-ones

H. Loghmani-Khouzani^a,*, B. Osmailowski^b, R. Gawinecki^b, E. Kolehmainen^c, R.W. Harrington^d and W. Clegg^d

^aDepartment of Chemistry, Faculty of Sciences, University of Isfahan 81746-73441 IR Iran
^bDepartment of Chemistry, Technical and Agricultural University, Seminaryjna 3PL-85-326 Bydgoszcz, Poland
^cDepartment of Chemistry, P.O. Box 35, FIN-40014, University of Jyväskylä, Finland
^dSchool of Natural Sciences (Chemistry), University of Newcastle, Newcastle upon Tyne NE1 7RU, U.K

(Received1 January 2006 , Accepted 15 March 2006)

      1,1-Difluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1a, 1,1,1-trifluoro-3-(1H-quinolin-2-ylidene)propan-2-one 1b, 1,1,1-trifluoro-3-(4-chloro-1H-quinolin-2-ylidene)propan-2-one 1c and 1,3-dibromo-1,1-difluoro-3-(2-quinolyl)propan-2-one 2 are prepared and characterized by various spectroscopic techniques. The crystal structure of 1a is determined by X-ray diffraction. Furthermore, a series of previously known non-halogenated (1H-quinolin-2-ylidene)propan-2-ones 1d-1h are oxidized with AgBrO₃ in the presence of AlCl₃. In all cases, 2-(1-bromo-1-chloromethyl)quinoline 3 is obtained in high yield. The bromination order and sites of 1a are analyzed based on ab initio MP2 and DFT calculations for the molecule and its anions.