SeO₂-Mediated Oxidation of 1,3-Diazabuta-1,3-dienes: A Single-Pot Synthesis of Functionalized 4-Hydroxyimidazoles

Abstract

A single-pot novel synthesis of variedly substituted 4-hydroxyimidazoles by SeO₂-mediated oxidation of 1-aryl-2-phen­yl/thiomethyl/secondary amino-4-N,N-dimethylamino-4-methyl-1,3-diazabuta-1,3-dienes is reported.

Key words

functionalized imidazoles - selenium dioxide - 1,3-di­azabuta-1,3-dienes

References and Notes

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12

2,3-Diphenyl-3H-imidazol-4-ol (2a): mp 159-160 °C. Anal. Calcd for C₁₅H₁₂N₂O (%): C, 76.25; H, 5.12; N, 11.86. Found C, 76.12; H, 5.03; N, 12.08. ¹H NMR (300 MHz): δ = 7.28 (m, 1 H, ArH), 7.45-7.90 (m, 8 H, ArH), 7.96-8.00 (m, 3 H, 2 ArH + OH exchangeable with D₂O). ¹³C NMR (75.4 MHz): δ = 119.8, 120.1, 124.5, 127.0, 128.8, 129.0, 129.3, 131.8, 134.5, 143.2, 145.8. MS: m/z = 236 [M⁺].
3-Phenyl-2-piperidin-1-yl-3H-imidazol-4-ol (2b): mp 143-144 °C. Anal. Calcd for C₁₄H₁₇N₃O: C, 69.11; H, 7.04; N, 17.27. Found: C, 69.25; H, 6.96; N, 17.21. ¹H NMR (300 MHz): δ = 1.65-1.69 (m, 6 H, -CH₂CH₂CH₂-), 3.54-3.58 (m, 4 H, -CH₂NCH₂-), 7.05-7.14 (m, 4 H, ArH), 7.22-7.27 (m, 2 H, ArH), 10.72 (s, 1 H, OH exchangeable with D₂O). ¹³C NMR (75.4 MHz): δ = 25.2 (-CH₂), 26.0 (-CH₂CH₂-), 44.4 (-CH₂NCH₂-), 118.0, 126.5, 128.2, 129.1, 134.2, 142.2, 146.2. MS: m/z = 243.
(1,2-Diphenyl-1H-imidazol-4-yl)dimethylamine (10a): mp 116-118 °C. Anal. Calcd. for C₁₇H₁₇N₃: C, 77.54; H, 6.51; N, 15.96. Found: C, 77.42; H, 6.38; N, 16.20. ¹H NMR (300 MHz): δ = 3.1 [s, 6 H, -N(CH₃)₂], 7.18-7.48 (m, 11 H, ArH). ¹³C (75.4 MHz): δ = 44.0 [-N(CH₃)₂], 121.2, 122.8, 123.0, 124.8, 126.2, 128.1, 128.7, 131.0, 132.7, 136.2, 148.3. MS: m/z 263 [M⁺].