Addition of Arylboronic Acids to Nitriles in Aqueous Media Catalyzed by a 2,2′-Bipyridine-Cyclopalladated Ferrocenylimine Complex

Abstract

The addition of arylboronic acids to nitriles catalyzed by a bipyridine-cyclopalladated ferrocenylimine complex in aqueous media was developed. The reactions could be conducted under acidic or basic conditions in aqueous media. The addition of NH₄Cl was found to have a drastic effect on the reaction yields.

Key words

cyclopalladated ferrocenylimine complex - arylboronic acids - nitriles - bipyridine - catalysis

References and Notes

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8

General Procedure In a bottle was placed NH₄Cl, which was then dried at 60 °C in vacuo for 6 h prior to use. A reaction vessel was charged with 0.5 mmol of benzonitrile, 1.5 mmol of PhB(OH)₂, 3.0 mmol of NH₄Cl, 0.5 mmol of sodium dodecyl sulfonate (SDS), Pd catalyst 2 in 2.0 mL of H₂O incubated in a oil bath at 100 °C for 24 h. After cooling, the reaction mixture was diluted with 10 mL brine. The aqueous layer was extracted with CH₂Cl₂ and dried over Na₂SO₄. After evaporation of the solvent the residue was subjected to TLC (PE-CH₂Cl₂). The prepared compounds were identified by ¹H NMR, ¹³C NMR, and MS. The new compound 3j was also identified by HRMS (ESI).
Selected Spectroscopic Data:
Catalyst 2: mp: 228-230 °C (dec.). ¹H NMR (400 MHz, MeOD): δ = 2.12 (s, 3 H), 2.45 (s, 3 H), 4.36 (s, 5 H), 4.65 (t, J = 2.4 Hz, 1 H), 4.81 (d, J = 2.4 Hz, 1 H), 4.95 (d, J = 2.0 Hz, 1 H), 6.33 (d, J = 4.8 Hz, 1 H), 7.13 (t, J = 6.0 Hz, 3 H), 7.38 (d, J = 6.8 Hz, 2 H), 7.79 (t, J = 6.0 Hz, 1 H), 8.02 (t, J = 7.6 Hz, 1 H), 8.27 (t, J = 7.6 Hz, 1 H), 8.35 (d, J = 7.6 Hz, 1 H), 8.43 (d, J = 7.6 Hz, 1 H), 9.20 (d, J = 4.8 Hz, 1 H). ¹³C NMR (100 MHz, MeOD): δ = 17.3, 21.1, 70.6, 70.8, 72.2, 75.0, 92.1, 98.8, 124.2, 125.3, 127.3, 128.6, 131.8, 139.4, 141.4, 141.8, 145.5, 149.8, 154.1, 155.5, 157.8, 189.4. HRMS (ESI+): m/z calcd for C₂₉H₂₆N₃FeClPd [M - Cl]⁺: 578.0511; found: 578.0518. IR (KBr): ν = 3018, 1633, 1600, 1473, 1438, 1368, 1227, 1153, 1106, 1073, 1027, 810, 776, 494 cm^-1.
Compound 3a: ¹H NMR (400 MHz, CDCl₃): δ = 2.40 (s, 3 H), 4.26 (s, 2 H), 7.23-7.32 (m, 7 H), 7.91 (d, J = 7.4 Hz, 2 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 21.7, 45.4, 126.8, 128.6, 128.8, 129.3, 129.4, 134.1, 134.8, 144.0, 197.3 ppm. MS (ESI+): m/z = 211.1 [M + H]⁺, 233.1 [M + Na]⁺, 249.0 [M + K]⁺.
Compound 3c: ¹H NMR (400 MHz, CDCl₃): δ = 3.86 (s, 3 H), 4.23 (s, 2 H), 6.91-6.94 (m, 2 H), 7.24-7.33 (m, 5 H), 7.98-8.00 (m, 2 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 45.3, 55.5, 113.8, 126.8, 128.6, 129.4, 129.7, 131.0, 135.0, 163.5, 196.2 ppm. MS (ESI+): m/z = 227.3 [M + H]⁺, 249.2 [M + Na]⁺, 265.2 [M + K]⁺.
Compound 3e: ¹H NMR (400 MHz, CDCl₃): δ = 4.27 (s, 2 H), 7.25-7.28 (m, 5 H), 7.32-7.36 (m, 2 H), 8.05-8.07 (m, 2 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 45.6, 120.3 (q, J = 257.4 Hz), 120.4, 127.1, 128.8, 129.4, 130.6, 134.1, 134.8, 152.7, 196.0 ppm. MS (ESI+): m/z = 281.0 [M + H]⁺, 303.1 [M + Na]⁺, 319.0 [M + K]⁺.
Compound 3f: ¹H NMR (400 MHz, CDCl₃): δ = 7.47 (t, J = 7.6 Hz, 4 H), 7.57 (t, J = 7.4 Hz, 2 H), 7.79-7.81 (m, 4 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 128.2, 130.0, 132.3, 137.5, 196.7 ppm. MS (ESI+): m/z = 183.1 [M + H]⁺, 205.1 [M + Na]⁺, 221.0 [M + K]⁺.
Compound 3j: ¹H NMR (400 MHz, CDCl₃): δ = 7.52-7.56 (m, 2 H), 7.66-7.70 (m, 1 H), 7.80-7.83 (m, 2 H), 8.00-8.04 (m, 2 H), 8.17-8.19 (m, 2 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 119.7 (q, J = 324.1 Hz), 128.8, 130.2, 130.7, 130.9, 133.8, 134.2, 135.9, 144.8, 194.6 ppm. MS (ESI+): m/z = 337.4 [M + Na]⁺, 353.7 [M + K]⁺. HRMS (ESI+): m/z calcd for C₁₄H₉F₃SO₃ [M + H]⁺: 315.0303; found: 315.0300.
Compound 3k: ¹H NMR (400 MHz, CDCl₃): δ = 6.92-6.96 (m, 2 H), 7.46-7.49 (m, 2 H), 7.55-7.59 (m, 1 H), 7.75-7.80 (m, 4 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 115.4, 128.3, 129.7, 129.9, 132.2, 133.1, 138.0, 160.6, 196.7 ppm. MS (ESI+): m/z = 199.2 [M + H]⁺, 221.1 [M + Na]⁺, 237.1 [M + K]⁺.
Compound 3l: ¹H NMR (400 MHz, CDCl₃): δ = 5.28 (s, 2 H), 6.94-7.01 (m, 3 H), 7.26-7.31 (m, 2 H), 7.48-7.52 (m, 2 H), 7.60-7.64 (m, 1 H), 8.00-8.02 (m, 2 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 70.8, 114.8, 121.7, 128.2, 128.8, 129.6, 133.9, 134.6, 158.0, 194.6 ppm. MS (ESI+): m/z = 213.1 [M + H]⁺, 235.0 [M + Na]⁺, 251.0 [M + K]⁺.
Compound 3m: ¹H NMR (400 MHz, CDCl₃): δ = 7.53 (t, J = 7.7, 2 H), 6.64-7.68 (m, 1 H), 7.79-7.81 (m, 2 H), 7.93-7.96 (m, 2 H), 8.33-8.36 (m, 2 H) ppm. ¹³C NMR (100 MHz, CDCl₃): δ = 123.6, 128.7, 130.1, 130.7, 133.5, 136.3, 142.9, 149.9, 194.8 ppm. MS (ESI+): m/z = 228.4 [M + H]⁺, 250.3 [M + Na]⁺.