SiO₂-TBD as New Heterogeneous Catalyst for the Nef Conversion of ­Secondary Nitroalkanes under Neat Conditions

Abstract

Treatment of secondary nitroalkanes with neat silica-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), at room temperature, allows the direct conversion of the secondary nitro groups to the corresponding keto carbonyls.

reaction - nitroalkanes - ketones - heterogeneous catalysis - solventless conditions - SiO₂-TBD

References and Notes

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12

Selected Analytical Data for Compounds 2a-e.
Compound 2a: oil. IR: 1714, 698 cm^-1. ¹H NMR (CDCl₃): δ = 0.92 (t, 3 H, J = 7.3 Hz), 1.51-1.70 (m, 2 H), 1.84-2.01 (m, 2 H), 2.37 (t, 2 H, J = 7.3 Hz), 2.42 (t, 2 H, J = 7.3 Hz), 2.64 (t, 2 H, J = 7.5 Hz), 7.15-7.37 (m, 5 H). ¹³C NMR (CDCl₃): δ = 13.8, 17.3, 25.2, 35.1, 41.9, 44.8, 125.9, 128.4, 128.5, 141.6, 211.0. MS (EI, 70eV): m/z (%) = 190 [M⁺], 175, 147, 129, 115, 104 (100), 91, 77, 71, 65, 58, 51, 43, 29. Anal. Calcd for C₁₃H₁₈O (190.28): C, 82.06; H, 9.53. Found: C, 82.34; H, 9.71.
Compound 2b: oil. IR: 1732, 1702, 1192 cm^-1. ¹H NMR (CDCl₃): δ = 0.84-0.89 (m, 6 H), 1.23-1.38 (m, 30 H), 1.50-1.68 (m, 8 H), 2.25-2.33 (m, 2 H), 2.34-2.44 (m, 4 H), 4.03 (t, 2 H, J = 6.7 Hz). ¹³C NMR (CDCl₃): δ = 14.2, 14.3, 22.7, 22.9, 23.5, 24.0, 24.7, 26.1, 28.9, 29.1, 29.5, 29.6, 29.7, 29.8, 29.9, 30.0, 31.8, 32.1, 34.1, 34.3, 42.5, 43.1, 64.8, 64.9, 173.7, 211.1. MS (EI, 70eV): m/z (%) = 424 [M⁺], 354, 197, 168, 145, 127, 113, 83, 57, 43 (100), 29. Anal. Calcd for C₂₇H₅₂O₃ (424.70): C, 76.36; H, 12.34. Found: C, 76.26; H, 12.25.
Compound 2c: oil. IR: 1715 cm^-1. ¹H NMR (CDCl₃): δ = 0.90 (t, 3 H, J = 6.6 Hz), 1.20-1.39 (m, 4 H), 1.51-1.67 (m, 2 H), 2.20 (s, 3 H), 2.46 (t, 2 H, J = 7.5 Hz), 2.64-2.76 (m, 4 H). ¹³C NMR (CDCl₃): δ = 13.9, 23.5, 25.4, 30.0, 31.4, 36.0, 36.9, 42.8, 207.3, 209.7. MS (EI, 70eV): m/z 170 [M⁺], 127, 114, 99, 43. Anal. Calcd for C₁₀H₁₈O₂ (170.25): C, 70.55; H, 10.66. Found: C, 70.81; H, 10.84.
Compound 2d: oil. IR: 1701 cm^-1. ¹H NMR (CDCl₃): δ = 0.88 (t, 6 H, J = 6.6 Hz), 1.20-1.34 (m, 46 H), 1.52-1.62 (m, 4 H), 2.37 (t, 4 H, J = 7.4 Hz). ¹³C NMR (CDCl₃): δ = 14.3, 22.9, 24.1, 29.4, 29.50, 29.53, 29.58, 29.6, 29.7, 29.8, 29.84, 29.88, 29.92, 32.1, 32.2, 43.0, 212.0. MS (EI, 70eV): m/z (%) = 436 [M⁺], 296, 207, 185, 170 (100), 97, 71, 57, 41. Anal. Calcd for C₃₀H₆₀O (436.80): C, 82.49; H, 13.85. Found: C, 82.81; H, 14.22.
Compound 2e: oil. IR: 1728, 1705, 1190 cm^-1. ¹H NMR (CDCl₃): δ = 0.90 (t, 3 H, J = 7.2 Hz), 1.56-1.68 (m, 2 H), 2.42 (t, 2 H, J = 7.2 Hz), 2.57 (t, 2 H, J = 6.5 Hz), 2.71 (t, 2 H, J = 6.5 Hz), 3.66 (s, 3 H). ¹³C NMR (CDCl₃): δ = 13.9, 17.5, 27.9, 37.2, 44.9, 52.0, 173.5, 209.2. MS (EI, 70eV): m/z (%) = 158 [M⁺], 130, 127, 115 (100), 98, 87, 71, 43. Anal. Calcd for C₈H₁₄O₃ (158.20): C, 60.74; H, 8.92. Found: C, 60.49; H, 9.10.