Expeditious Synthesis of 1,2-Diaminoimidazoles under Solvent-Free Conditions

Abstract

1,2-Diaminoimidazoles are obtained in good yields by reaction of 1,2-diaza-1,3-butadienes with cyanamide at 50 °C under solvent-free conditions. These compounds are important intermediates for the synthesis of imidazo[1,2-b][1,2,4]triazines.

1,2-diaza-1,3-butadienes - 1,2-diaminoimidazoles - hydrazones - Michael additions - cylizations

References

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9

Analytical data of compound 3a: mp 173-177 °C. IR 3435, 3323, 1739, 1704, 1627 cm^-1. ¹H NMR (DMSO-d ₆): δ = 2.16 (s, 3 H), 3.65 (s, 3 H), 3.68 (s, 3 H), 5.88 (s, 2 H), 10.36 (s, 1 H). ¹³C NMR (DMSO-d ₆): δ = 9.0, 50.5, 52.7, 120.3, 131.4, 148.0, 155.1, 163.3. MS: m/z (%) = 228 (54) [M⁺], 196 (100). Anal. Calcd for C₈H₁₂N₄O₄: C, 42.10; H, 5.30; N, 24.55. Found: C, 42.17; H, 5.28; N, 24.58.

10

Analytical data of compound 4: oil. IR 3310, 2258, 2202 cm^-1. ¹H NMR (DMSO-d ₆): δ = 1.29 (s, 18 H), 2.23 (s, 3 H), 3.66 (s, 3 H), 5.27 (s, 1 H), 10.24 (br s, 1 H). ¹³C NMR (CDCl₃-d ₆): δ = 14.2, 27.9, 29.6, 51.0, 51.5, 82.7, 114.2, 132.8, 144.4, 150.0, 161.9. MS: m/z (%) = 326 (4) [M⁺], 270 (10), 211 (19), 182 (26), 170 (36), 155 (72), 123 (100). Anal. Calcd for C₁₅H₂₆N₄O₄: C, 55.20; H, 8.03; N, 17.17. Found: C, 55.16; H, 8.09; N, 17.15.

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