Synlett 2005(19): 2999-3001  
DOI: 10.1055/s-2005-921897
LETTER
© Georg Thieme Verlag Stuttgart · New York

An Atom-Economical and Environmentally Benign Preparation of ­Unsymmetrical Bis-allyl Ethers via Dimerization of Baylis-Hillman Adducts Catalyzed by Cesium Hydroxide Monohydrate

Yunkui Liua, Jian Lib, Hui Zhenga, Danqian Xub, 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
Fax: +86(571)88320609; e-Mail: chrc@zjut.edu.cn;
b Department of Chemistry, Zhejiang University, Xi-xi Campus, Hangzhou 310028, P. R. of China
c State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. of China
Further Information

Publication History

Received 13 September 2005
Publication Date:
04 November 2005 (online)

Abstract

Promoted by a catalytic amount of cesium hydroxide monohydrate, unsymmetrical bis-allyl ethers consisting of an E-allylic unit and a terminal allylic unit were formed via dimerization of Baylis-Hillman adducts in moderate to good yields at room temperature.

12

Typical Experimental Procedure. In a 25-mL flask was charged with CsOH·H2O (50 mg, 0.3 mmol) and THF (10 mL). The suspension was stirred at r.t. for 10 min. The Baylis-Hillman adduct 1 (1 mmol) was added to the flask and stirred at r.t. for 0.5-1 h. The reaction mixture was poured into Et2O (50 mL), washed with H2O (2 × 25 mL) and brine (35 mL). The combined ethereal layers were dried over MgSO4. After evaporation of solvent the residue was purified by chromatography using cyclohexane-EtOAc (6:1) as eluent.

13

Spectroscopic data of 2b: oil. 1H NMR (400 MHz, CDCl3): δ = 2.34 (s, 3 H, CH 3), 2.37 (s, 3 H, CH 3), 3.71 (s, 3 H, OCH 3), 3.79 (s, 3 H, OCH 3), 4.20 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 4.33 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 5.35 (s, 1 H, O-CH-Ar), 6.00 (t, 1 H, 2 J = 1.6 Hz, terminal olefin-H), 6.35 (t, 1 H, 2 J = 1.6 Hz, terminal olefin-H), 7.13 (d, 2 H, J = 8.0 Hz, ArH), 7.15 (d, 2 H, J = 8.0 Hz, ArH), 7.27 (d, 2 H, J = 8.0 Hz, ArH), 7.39 (d, 2 H, J = 8.0 Hz, ArH), 7.87 (s, 1 H, ArCH=). 13C NMR (400 MHz, CDCl3): δ = 21.16, 21.39, 51.74, 51.97, 63.72, 79.28, 125.53, 127.81, 128.93, 129.18, 129.97, 131.80, 136.29, 137.60, 139.63, 140.84, 143.24, 144.95, 166.42, 168.15. IR (film): ν = 3073, 3025, 1721, 1631, 1594, 1066 cm-1. MS (70 eV): m/z (%) = 394 [M+]. Anal. Calcd for C24H26O5: C, 73.08; H, 6.64. Found: C, 73.25; H, 6.70. According to NOESY experiment, there is no NOE correlation between the signals of the internal olefin proton and the allylic methylene protons.

14

Selected spectroscopic data for compound 2:
Compound 2a: oil. 1H NMR (400 MHz, CDCl3): δ = 3.69 (s, 3 H, OCH 3), 3.80 (s, 3 H, OCH 3), 4.23 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 4.34 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 5.33 (s, 1 H, OCH-Ph), 5.90 (t, 1 H, 2 J = 1.2 Hz, terminal-olefin-H), 6.31 (t, 1 H, 2 J = 1.2 Hz, terminal-olefin-H), 7.25-7.51 (m, 10 H, ArH), 7.91 (s, 1 H, ArCH=). IR (film): ν = 3078, 3030, 1720, 1633, 1600, 1067 cm-1. MS (70 eV): m/z (%) = 366 [M+]. Anal. Calcd for C22H22O5: C, 72.12; H, 6.05. Found: C, 72.25; H, 6.01.
Compound 2c: oil. 1H NMR (400 MHz, CDCl3): δ = 3.70 (s, 3 H, OCH 3), 3.80 (s, 3 H, OCH 3), 4.20 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 4.29 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 5.34 (s, 1 H, O-CH-Ar), 5.94 (t, 1 H, 2 J = 1.2 Hz, terminal-olefin-H), 6.36 (t, 1 H, 2 J = 1.2 Hz, terminal-olefin-H), 7.29-7.36 (m, 6 H, ArH), 7.41 (d, 2 H, J = 8.0 Hz, ArH), 7.85 (s, 1 H, ArCH=). 13C NMR (400 MHz, CDCl3): δ = 51.80, 52.08, 63.56, 78.79, 125.90, 128.43, 128.74, 129.11, 131.09, 131.36, 132.95, 133.80, 135.54, 137.83, 140.52, 143.54, 166.05, 167.58. IR (film): ν = 3070, 3026, 1724, 1632, 1593, 1118 cm-1. MS (70 eV): m/z (%) = 434 [M+], 436 [M+ + 2]. Anal. Calcd for C22H20Cl2O5: C, 60.70; H, 4.63. Found: C, 60.56; H, 4.69.
Compound 2d: oil. 1H NMR (400 MHz, CDCl3): δ = 3.74 (s, 3 H, OCH 3), 3.82 (s, 3 H, OCH 3), 4.25 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 4.32 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 5.76 (t, 1 H, 2 J = 1.2 Hz, terminal olefin-H), 5.83 (s, 1 H, O-CH-Ar), 6.41 (t, 1 H, 2 J = 1.2 Hz, terminal olefin-H), 7.22-7.42 (m, 6 H, ArH), 7.52-7.63 (m, 2 H, ArH), 8.04 (s, 1 H, ArCH=). 13C NMR (400 MHz, CDCl3): δ = 52.15, 52.40, 64.72, 76.07, 127.08, 127.13, 127.51, 129.21, 129.40, 128.64, 129.73, 130.19, 130.66, 131.19, 131.49, 133.28, 136.88, 139.84, 141.38, 141.83, 166.48, 167.61. IR (film): ν = 3066, 3025, 1721, 1635, 1592, 1067 cm-1. MS (70 eV): m/z (%) = 434 [M+], 436 [M+ + 2]. Anal. Calcd for C22H20Cl2O5: C, 60.70; H, 4.63. Found: C, 60.64; H, 4.56.
Compound 2e: oil. 1H NMR (400 MHz, CDCl3): δ = 3.79 (s, 3 H, OCH 3), 3.80 (s, 3 H, OCH 3), 3.81 (s, 3 H, OCH 3), 3.84 (s, 3 H, OCH 3), 4.25 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 4.34 (d, 1 H, 2 J = 10.0 Hz, methylene-H), 5.35 (s, 1 H, O-CH-Ar), 6.01 (t, 1 H, 2 J = 1.2 Hz, terminal olefin-H), 6.36 (t, 1 H, 2 J = 1.2 Hz, terminal olefin-H), 6.86 (d, 2 H, J = 8.0 Hz, ArH), 6.90 (d, 2 H, J = 8.0 Hz, ArH), 7.32 (d, 2 H, J = 8.0 Hz, ArH), 7.48 (d, 2 H, J = 8.0 Hz, ArH), 7.86 (s, 1 H, ArCH=). IR (film): ν = 3075, 3020, 1721, 1629, 1606, 1120 cm-1. MS (70 eV): m/z (%) = 426 [M+]. Anal. Calcd for C24H26O7: C, 67.59; H, 6.15. Found: C, 67.40; H, 6.24.