W. Watson, Guanmin Wu, M. Richmond
Nov 1, 2004
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Influential Citations
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Journal
Journal of Chemical Crystallography
Abstract
Refluxing equimolar amounts of 2,3-dichloromaleic anhydride and o-phenylenediamine in toluene affords the three compounds 2,3-dichloro-N-o-C6H4(NH2)maleimide (1), N,N′-o-C6H4-bis(2,3-dichloromaleimide) (2), and 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one (3). Under these conditions the former compound is observed as the major product. Repeating the same reaction in the presence of added PTSA furnishes the heterocyclic compound 2,3-dichloropyrrolo[1,2-a]benzimidazol-1-one, as the major product. Treatment of compound 1 with PTSA, coupled with water removal, gives compound 3 in near quantitative yield and confirms the intermediacy of 1en route to 3. The new compounds 1–3 have been isolated by column chromatography and characterized in solution by spectroscopic methods. The molecular structures of the maleimide-substituted compounds 1 and 2 were determined by X-ray crystallography. 2,3-Dichloro-N-o-C6H4(NH2)maleimide crystallizes in the monoclinic space group P21/c, a = 20.693(8) Å, b = 5.712(2) Å, c = 8.787(4) Å, β = 92.819(7)°, V = 1037.3(7) Å3, Z = 4, and dcalc = 1.646 Mg/m3; R = 0.0604, Rw = 0.1140 for 1354 reflections with I > 2 σ (I), with N,N′-o-C6H4-bis(2,3-dichloromaleimide) crystallizing in the triclinic space group P−1, a = 7.9509(4) Å, b = 10.2532(6) Å, c = 12.1126(7) Å, α = 82.637(1)°, β = 87.799(1)°, γ = 71.634(1)°, V = 929.42(9) Å3, Z = 2, and dcalc = 1.651 Mg/m3; R = 0.0499, Rw = 0.1545 for 1977 reflections with I > 2σ (I).