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Synlett 2007(11): 1671-1674  
DOI: 10.1055/s-2007-984507
LETTER
© Georg Thieme Verlag Stuttgart · New York

Al/PbCl2-Catalyzed DMF-Mediated Reductive Coupling of Baylis-Hillman Acetates with Tetrachloromethane

Yunkui Liua, Danqian Xua, Zhenyuan Xu*a, Yongmin Zhang*b,c
a State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, P. R. of China
b Department of Chemistry, Zhejiang University, Xi-xi Campus, Hangzhou 310028, P. R. of China
Fax: +86(571)88320066; e-Mail: greensyn@zjut.edu.cn;
c State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. of China
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Publication History

Received 23 January 2007
Publication Date:
25 June 2007 (online)

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Abstract

2-(2,2,2-Trichloroethyl)alk-2-enoates could be formed in good E-selectivity by the reductive coupling of Baylis-Hillman acetates with tetrachloromethane in good 76-92% yields in the presence of catalytic Al/PbCl2 and DMF.

Key words

reductive coupling - Baylis-Hillman acetate - tetra­chloromethane - catalytic system

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General Procedure for the Synthesis of 2-(2,2,2-Tri-chloroethyl)alk-2-enoates 2 In a 25 mL flask were added Al powder (0.032 g, 1.2 mmol), PbCl2 (0.055g, 0.2 mmol), Baylis-Hillman acetate 1 (1 mmol), CCl4 (0.20 mL, 2.0 mmol), and anhyd DMF (5 mL). The mixture was stirred at r.t. for 2-4 h. Upon completion, the solvent was removed under vacuum. Then, to the flask was added 10 mL 5% HCl for quenching the reaction, and the mixture was extracted by CH2Cl2 (2 × 30 mL), washed with brine (15 mL), dried over MgSO4. After evaporation of the solvent, the residue was purified by chromatography using cyclohexane-EtOAc (6:1) as eluent to give pure 2.

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Data for Compounds 2
Compound (E)-2a: 1H NMR (400 MHz, CDCl3): δ = 3.85 (s, 3 H, OCH3), 4.17 (s, 2 H, CH2), 7.32-7.39 (m, 5 H, ArH), 7.94 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 49.56, 52.32, 98.27, 126.66, 128.69, 128.84, 128.92, 134.88, 144.85, 168.27. IR (film): ν = 3060, 3028, 2952, 1724, 1633, 1577 cm-1. MS (70 eV): m/z (%) = 292 [M+]. Anal. Calcd for C12H11Cl3O2: C, 49.09; H, 3.78. Found: C, 49.38; H, 3.74.
Compound (E)-2b: 1H NMR (400 MHz, CDCl3): δ = 2.37 (s, 3 H, CH3), 3.86 (s, 3 H, OCH3), 4.19 (s, 2 H, CH2), 7.21 (d, 2 H, J = 8.0 Hz, ArH), 7.35 (d, 2 H, J = 8.0 Hz, ArH), 7.91 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 21.30, 49.74, 52.31, 98.48, 125.76, 129.14, 129.46, 131.97, 139.33, 144.98, 168.54. IR (film): ν = 3027, 3025, 2997, 2952, 1720, 1632, 1609 cm-1. MS (70 eV): m/z (%) = 306 [M+]. Anal. Calcd for C13H13Cl3O2: C, 50.76; H, 4.26. Found: C, 50.48; H, 4.30.
Compound (E)-2c: 1H NMR (400 MHz, CDCl3): δ = 3.84 (s, 3 H, OCH3), 3.86 (s, 3 H, OCH3), 4.10 (s, 2 H, CH2), 6.91 (d, 1 H, J = 8.0 Hz, ArH), 6.98 (t, 1 H, J = 8.0 Hz, ArH), 7.29 (d, 1 H, J = 8.0 Hz, ArH), 7.34 (t, 1 H, J = 8.0 Hz, ArH), 8.03 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 50.0, 52.28, 55.53, 98.51, 111.0, 120.54, 124.35, 126.91, 129.10, 130.36, 141.97, 157.29, 168.27. IR (film): ν = 3042, 3001, 2951, 2846, 1719, 1637, 1597 cm-1. MS (70 eV): m/z (%) = 322 [M+]. Anal. Calcd for C13H13Cl3O3: C, 48.25; H, 4.05. Found: C, 48.53; H, 4.08.
Compound (E)-2d: 1H NMR (400 MHz, CDCl3): δ = 3.84 (s, 3 H, OCH3), 4.17 (s, 2 H, CH2), 6.0 (s, 2 H, OCH2O), 6.83 (d, 1 H, J = 8.0 Hz, ArH), 6.95 (d, 1 H, J = 8.0 Hz, ArH), 6.99 (s, 1 H, ArH), 7.83 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 49.56, 52.30, 98.41, 101.44, 108.55, 108.84, 124.39, 124.90, 128.57, 144.52, 147.96, 148.39, 168.48. IR (film): ν = 3054, 3002, 2900, 1718, 1616 cm-1. MS (70 eV): m/z (%) = 336 [M+]. Anal. Calcd for C13H11Cl3O4: C, 46.25; H, 3.28. Found: C, 46.52; H, 3.25
Compound (E)-2e: 1H NMR (400 MHz, CDCl3): δ = 3.86 (s, 3 H, OCH3), 4.13 (s, 2 H, CH2), 7.35 (d, 2 H, J = 8.0 Hz, ArH), 7.40 (d, 2 H, J = 8.0 Hz, ArH), 7.88 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 49.59, 52.48, 98.10, 127.33, 129.07, 130.22, 133.37, 142.13, 143.51, 168.10. IR (film): ν = 3003, 2952, 2850, 1710, 1635, 1591 cm-1. MS (70 eV): m/z (%) = 328 [M+]. Anal. Calcd for C12H10Cl4O2: C, 43.94; H, 3.07. Found: C, 43.68; H, 3.11.
Compound (E)-2f: 1H NMR (400 MHz, CDCl3): δ = 3.88 (s, 3 H, OCH3), 4.04 (s, 2 H, CH2), 7.21-7.43 (m, 4 H, ArH), 7.97 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 49.41, 52.50, 97.70, 126.18, 128.43, 129.25, 129.79, 129.90, 133.87, 142.41, 167.60. IR (film): ν = 3061, 2998, 2952, 1721, 1641, 1590 cm-1. MS (70 eV): m/z (%) = 328 [M+]. Anal. Calcd for C12H10Cl4O2: C, 43.94; H, 3.07. Found: C, 43.75; H, 3.04.
Compound (E)-2g: 1H NMR (400 MHz, CDCl3): δ = 3.88 (s, 3 H, OCH3), 4.01 (s, 2 H, CH2), 7.24 (d, 1 H, J = 8.0 Hz, ArH), 7.29 (d, 1 H, J = 8.0 Hz, ArH), 7.45 (s, 1 H, ArH), 7.89 (s, 1 H, ArCH=). 13C NMR (100 MHz, CDCl3): δ = 49.34, 52.54, 97.49, 127.25, 128.98, 129.70, 130.0, 132.37, 134.59, 135.12, 140.07, 141.12, 166.50. IR (film): ν = 3092, 3001, 2954, 1729, 1643, 1586 cm-1. MS (70 eV): m/z (%) = 362 [M+]. Anal. Calcd for C12H9Cl5O2: C, 39.76; H, 2.50. Found: C, 39.51; H, 2.53.
Compound (E)-2h: 1H NMR (400 MHz, CDCl3): δ = 3.90 (s, 3 H, OCH3), 4.13 (s, 2 H, CH2), 7.64 (t, 1 H, J = 8.0 Hz, ArH), 7.75 (d, 1 H, J = 8.0 Hz, ArH), 7.97 (s, 1 H), 8.22 (d, 1 H, J = 8.0 Hz, ArH), 8.27 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 49.26, 52.61, 97.62, 123.37, 129.15, 129.84, 134.41, 136.54, 140.81, 141.90, 148.22, 167.45. IR (film): ν = 3086, 2954, 1725, 1639, 1532 cm-1. MS (70 eV):
m/z (%) = 337 [M+]. Anal. Calcd for C12H10Cl3NO2: C, 42.57; H, 2.98. Found: C, 42.33; H, 2.95.
Compound (E)-2i: 1H NMR (400 MHz, CDCl3): δ = 3.83 (s, 3 H, OCH3), 4.39 (s, 2 H, CH2), 6.51 (d, 1 H, J = 1.2 Hz, ArH), 6.74 (dd, 1 H, J 1 = 4.0 Hz, J 2 = 1.2 Hz, ArH), 7.42 (s, 1 H, ArCH=), 7.59 (d, 1 H, J = 4.0 Hz, ArH). 13C NMR (100 MHz, CDCl3): δ = 50.44, 52.30, 98.64, 112.16, 118.54, 121.02, 130.39, 145.17, 150.41, 168.35. IR (film): ν = 2952, 1717, 1636 cm-1. MS (70 eV): m/z (%) = 282 [M+]. Anal. Calcd for C10H9Cl3O3: C, 42.36; H, 3.20. Found: C, 42.58; H, 3.25.
Compound (E)-2j: 1H NMR (400 MHz, CDCl3): δ = 2.68 (q, 2 H, J = 8.0 Hz, CH2), 2.78 (t, 2 H, J = 8.0 Hz, CH2), 3.77 (s, 3 H, OCH3), 3.78 (s, 2 H, CH2), 7.09 (t, 1 H, J = 8.0 Hz, CH=), 7.16-7.31 (m, 5 H, ArH). 13C NMR (100 MHz, CDCl3): δ = 31.88, 34.44, 50.07, 52.11, 98.68, 126.27, 128.24, 128.36, 128.51, 140.42, 148.00, 167.73. IR (film): ν = 3063, 3028, 2950, 1723, 1646, 1603 cm-1. MS (70 eV): m/z (%) = 320 [M+]. Anal. Calcd for C14H15Cl3O2: C, 52.28; H, 4.70. Found: C, 52.54; H, 4.64.
Compound (E)-2k: 1H NMR (400 MHz, CDCl3): δ = 0.88 (t, 3 H, J = 6.8 Hz, CH3), 1.27-1.33 (m, 10 H), 2.37 (q, 2 H, J = 8.0 Hz, CH2), 3.78 (s, 3 H, OCH3), 3.85 (s, 2 H, CH2), 7.06 (t, 1 H, J = 8.0 Hz, CH=). 13C NMR (100 MHz, CDCl3): δ = 13.99, 22.55, 28.41, 29.01, 29.29, 30.08, 31.65, 50.20, 52.02, 98.88, 125.71, 149.75, 167.92. IR (film): ν = 2927, 2856, 1724, 1646 cm-1. MS (70 eV): m/z (%) = 314 [M+]. Anal. Calcd for C13H21Cl3O2: C, 49.46; H, 6.71. Found: C, 49.28; H, 6.66.