Synthesis and X-Ray Crystal Structure of Pyrrolo 1 2

Synthesis and X-Ray Crystal Structure of Pyrrolo[1, 2 -a]benzimidazoles By Prof. Adel M. Awadallah Islamic University of Gaza e-mail: awada@iugaza. edu. ps

• Contents • * Introduction • * Reaction of Nitrilimines with 2 - Cyanomethylbenzimidazole • * Reaction of Nitrilimines with 2 aminobenzimidazole • * Reaction of Nitrilimines with 2 - Aminopyrimidine

Introduction • * Nitriles in 1, 3 -Dipolar Cycloaddition • Synthesis of Heterocycles – • General Equation

Examples • Y. Al-Soud, N. Al-Masoudi, A. R. S. Ferwanah, Bioorganic & Medicinal Chemistry, 2003, 11, 1701 – 1708.

• Reaction of Nitrilimines with 2 Cyanomethylbenzimidazole • (Expecting to get a triazole derivative)

• Results M. Wt = 333 (351 – 18) → H 2 O is lost IR (CN is present, but no C=O)

Suggested Structure • Elwan, N. Tetrahedron, 2004, 60, 1161 -1166.

Which is the correct structure ? ? Mass Spectra IR Spectra 1 H-NMR 13 C-NMR 2 D-NMR X-Ray Can not Help Will Help

X-Ray Crystal Structure of the Product

Another Example of Structure Determination Problems

Which is the correct structure? ? Mass Spectra IR Spectra 1 H-NMR 13 C-NMR X-Ray Can not Help Will Help

Lit 1: L. A. Vlasova, I. Ya. Postovskii, Khim. Geterotsikl. Soedin. 1971, 7, 700 Lit 2: A. Awadallah, P. Rademacher, R. Boese, J. Prakt. Chem. 1995, 337, 636 - 640

• Reaction of Nitrilimines with 2 -aminobenzimidazole

• Spectral Data • MS m/z (327/329 M+. , chlorine isotopes). • IR (KBr) υ 3416, 3310, 3297(3 NH), 1683(C=O) cm-1 • 1 H-NMR (DMSO-D 6) δ 2. 5 (s, 3 H, CH ), 6. 4 (s, 2 H, 3 NH 2), 6. 6 (1 H, d, 7. 0 Hz, Ar. C-H), 6. 8 (1 H, t, 7. 0 Hz, Ar. C-H), 7. 0 (1 H, t, 7. 0 Hz, Ar. C-H), 7. 2 (1 H, d, 7. 0 Hz, Ar. C-H), 7. 4 (4 H, 2 d, 9. 0 Hz, 4 -Cl. C 6 H 4), 11. 0 (s, 1 H, NH); • 13 C-NMR (DMSO-D 6) δ 191. 2 (C=O), 155. 1, 144. 7 (2 C=N), 142. 6, 134. 1, 128. 8, 126. 7 (4 Ar. C), 129. 6, 121. 7, 118. 9, 117. 0, 115. 4, 108. 1 (6 Ar. C-H), 25. 6 (CH 3)

• Reaction of Nitrilimines with 2 -Aminopyrimidine

• Spectral Data • MS m/z (287 / 289 M+. , chlorine isotopes). • IR (KBr) υ No NH(s), No C=O • 1 H-NMR (DMSO-D 6) δ 2. 51 (s, 3 H, CH ), 3 5. 51 (1 H, t, 11. 0 Hz, Ar. C-H), 7. 55 (2 H, d, 9. 0 Hz, Ar. C-H), 7. 65 (1 H, d, 11. 0 Hz, CH), 7. 92 (2 H, d, 9. 0 Hz, Ar. C-H), 8. 66 (1 H, d, 11. 0 Hz, C-H), • 13 C-NMR (DMSO-D 6) δ 191. 66 (C=O), 169. 44, 160. 96, 129. 42, 124. 99, 101. 55 (5 Ar C-H), 161. 44, 157. 62, 136. 82, 132. 00 (4 Ar C), 27. 29 (CH 3)

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