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Synlett 2009(2): 302-305  
DOI: 10.1055/s-0028-1087518
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Heterocyclizations via TosMIC-Based Multicomponent Reactions: A New Approach to One-Pot Facile Synthesis of Substituted Quinoxaline Derivatives

Constantinos Neochoritis, Julia Stephanidou-Stephanatou*, Constantinos A. Tsoleridis*
Department of Chemistry, Laboratory of Organic Chemistry, University of Thessaloniki, 54124 Thessaloniki, Macedonia, Greece
Fax: +30(2310)997679; e-Mail: ioulia@chem.auth.gr; e-Mail: tsolerid@chem.auth.gr;
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Publication History

Received 6 August 2008
Publication Date:
15 January 2009 (online)

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Abstract

A novel multicomponent reaction involving o-phenylenediamines, aldehydes and p-toluenesulfonylmethyl isocyanide (TosMIC) in the presence of a base leading to the formation of quinoxalines in very good yields is described.

Key words

multicomponent reactions - TosMIC - quinoxalines

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Evolution of gas with alkaline pH and characteristic amine odor was detected.

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All melting points were determined on a Büchi apparatus and are uncorrected. The ¹H NMR and ¹³C NMR spectra were recorded on a Bruker AM 300 spectrometer in CDCl3 with TMS as internal standard. All coupling constants are given in Hz and chemical shifts are given in ppm.
Typical Experimental Procedure for the Preparation of 3e: To a stirred solution of o-phenylenediamine (1a; 1.0 mmol) in toluene (20 mL), 4-chlorobenzaldehyde (1.0 mmol) was added and stirring was continued for 5 min. Then TosMIC (1.0 mmol) and DABCO (1.2 mmol) were added and the reaction mixture was heated to 80 ˚C for 4 h. The resulting solution was initially washed with 5% HCl, then with H2O and dried. The solvent was distilled off under reduced pressure to yield the corresponding crude product mixture, which was purified by silica gel chromatography using petroleum ether-EtOAc (10:1) as eluent, to give quinoxaline 3e in 84% yield; yellow crystals; mp 136-
137 ˚C (ethanol) (lit. [³0] 137 ˚C). ¹H NMR: δ = 7.51 (dd, J = 8.8, 2.1 Hz, 2 H, 3′-H, 5′-H), 7.74 (dd, J = 8.8, 2.1 Hz, 1 H, 7-H), [³¹] 7.77 (dd, J = 8.8, 2.1 Hz, 1 H, 6-H), 8.10 (dd, J = 8.8, 2.1 Hz, 1 H, 5-H), 8.11 (dd, J = 8.8, 2.1 Hz, 1 H, 8-H), 8.12 (dd, J = 8.8, 2.0 Hz, 2 H, 2′-H, 6′-H), 9.27 (s, 1 H, 3-H). ¹³C NMR: δ = 128.7 (C-2′, C-6′), 129.1 (C-5), 129.4 (C-3′, C-5′), 129.5 (C-8), 129.8 (C-7), 130.4 (C-6), 135.1 (C-1′), 136.5 (C-4′), 141.6 (C-4a), 142.1 (C-8a), 150.5 (C-2). Anal. Calcd for C14H9ClN2 (240.69): C, 69.85; H, 3.74; N, 11.64. Found: C, 70.01; H, 3.83; N, 11.68.

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The multiplicities and chemical shifts of the aromatic protons have been confirmed after simulation with program SpinWorks, version 2.5, available from
ftp://davinci.chem.umanitoba.ca.