synthesis and some reactions of 3-chloro-2-(cyanomethylene)-1,2-dihydroquinoxalines合成和一些反应3-chloro-2u2014u2014(cyanomethylene)1、2-dihydroquinoxalines.pdf

Molecules 2004, 9, 223-231 molecules ISSN 1420-3049 Synthesis and Some Reactions of 3-Chloro-2-(cyanomethylene)- 1,2-dihydroquinoxalines Craig A Obafemi 1,* and Wolfgang Pfleiderer 2 1 Department of Chemistry, Obafemi Awolowo University, Ile-Ife, Osun State. Nigeria. Phone: (+234) 036 231 624 2 Fachbereich Chemie, Konstanz University, D-78457 Konstanz, Germany. E-mail: wolfgang.pfleiderer@uni-konstanz.de * Author to whom correspondence should be addressed; E-mail: craigoba@.ng or adeyemi01@ Received: 16 December 2002; in revised form 11 February 2004 / Accepted: 20 February 2004 / Published: 31 March 2004 Abstract: 2,3-Dichloroquinoxaline and some of its derivatives have been reacted with malononitrile and ethyl cyanoacetate to yield a variety of 3-chloro-2-(cyanomethylene)- 1,2-dihydroquinoxaline derivatives. The reaction of 3-chloro-2-(dicyanomethylene)-1,2- dihydroquinoxaline (2e) with pyridine and its methyl derivatives led to the zwitterionic structures 6a-6c. The structures of the newly synthesized compounds were assigned by spectroscopic data and elemental analyses. Keywords: 2,3-Dichloroquinoxaline, ethoxycarbonylcyanomethylene- and dicyano- methylene-3-chloro-1,2-dihydroquinoxalines, betaine structures, spectroscopic data Molecules 2004, 9 224 Introduction The two reactive chlorine atoms in 2,3-dichloroquionoxaline (1a) are prone to nucle