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Synlett 2007(3): 0494-0496  
DOI: 10.1055/s-2007-968033
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Pd(OAc)2-Mediated One-Pot Synthesis of Trisubstituted Alkenes via Michael Addition of a Stabilized Ylide to Baylis-Hillman Adducts [1]

A. Sai Krishna Murthy*, C. Rambabu, K. Vijeender, P. Bibhuti Bhusan, S. Chandrasekhar
Organic Chemistry Division I, Indian Institute of Chemical Technology, Hyderabad 500007, India
Fax: +91(40)27160512; e-Mail: saikrishna@iict.res.in;
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Publication History

Received 30 August 2006
Publication Date:
07 February 2007 (online)

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A Pd(OAc)2-Mediated One-Pot Synthesis of Trisubstituted Alkenes via Michael Addition of a Stabilized Ylide to Baylis-Hillman AdductsSynlett 2007; 2007(04): 0668-0668
DOI: 10.1055/s-2007-970749

Abstract

A simple and efficient stereoselective synthesis of Z- and E-isomers of trisubstituted alkenes has been developed by treating Baylis-Hillman (BH) acetates with palladium acetate and the ­stabilized ylide (ethoxycarbonylmethylene)triphenylphosphorane. ­Several ethyl acrylate and acrylonitrile-derived BH acetates were used as substrates, which yielded the corresponding trisubstituted alkenes stereoselectively in good yields.

Key words

Baylis-Hillman adducts - palladium acetate - E- and Z-trisubstituted alkenes - stabilized ylide

1

IICT communication No: 060602.

1

IICT communication No: 060602.

10

Typical Experimental Procedure: To a solution of the Baylis-Hillman acetate (0.0016 mol) in anhyd benzene (8 mL) were added(ethoxycarbonylmethylene)triphenylphos-phorane (0.0016 mol) and Pd(OAc)2 (6 mol%) and the solution was heated to reflux for 10-13 h (monitored by TLC). After completion of the reaction, H2O (2 mL) was added to the reaction mixture, which was extracted with EtOAc (3 × 10 mL). The combined organic layers were washed with H2O and brine, dried over anhyd Na2SO4, concentrated in vacuo and the crude product was purified by flash column chromatography. The yields of the trisubstituted alkenes are given in the Table [1] .
Spectroscopic data for selected compounds are given as follows: Compound 1a: 1H NMR (200 MHz, CDCl3): δ = 7.70 (s, 1 H), 7.30-7.41 (m, 5 H), 4.28 (q, J = 6.9 Hz, 2 H), 4.11 (q, J = 6.9 Hz, 2 H), 2.85-2.88 (m, 2 H), 2.51-2.56 (m, 2 H), 1.40 (t, J = 6.9 Hz, 3 H), 1.27 (t, J = 6.9 Hz, 3 H). IR (KBr): 1730, 1709, 1250, 1095 cm-1. ESI-MS: m/z = 299 [M + Na]+. Compound 2a: 1H NMR (300 MHz, CDCl3): δ = 7.69 (s, 1 H), 7.25 (d, J = 7.5 Hz, 2 H), 7.18 (d, J = 8.3 Hz, 2 H), 4.26 (q, J = 7.5 Hz, 2 H), 4.11 (q, J = 6.8 Hz, 2 H), 2.81-2.87 (m, 2 H), 2.48-2.54 (m, 2 H), 2.37 (s, 3 H), 1.35 (t, J = 6.8 Hz, 3 H), 1.25 (t, J = 7.5 Hz, 3 H). IR (KBr): 1737, 1710, 1250, 1050 cm-1. ESI-MS: m/z = 313 [M + Na]+. Compound 6a: 1H NMR (300 MHz, CDCl3): δ = 7.62 (s, 1 H), 7.53-7.59 (m, 1 H), 7.46-7.50 (m, 1 H), 7.28-7.35 (m, 2 H), 4.28 (q, J = 7.5 Hz, 2 H), 4.11 (q, J = 6.8 Hz, 2 H), 2.81-2.83 (m, 2 H), 2.50-2.55 (m, 2 H), 1.37 (t, J = 7.5 Hz, 3 H), 1.26 (t, J = 6.8 Hz, 3 H). IR (KBr): 2961, 1715, 1711, 1260, 1252, 1072, 1028 cm-1. ESI-MS: m/z = 355 [M + H]+, 379 [M + Na + H]+. Compound 7a: 1H NMR (200 MHz, CDCl3): δ = 7.48-7.87 (m, 5 H), 7.16 (s, 1 H), 4.16 (q, J = 6.9 Hz, 2 H), 2.60-2.81 (m, 4 H), 1.26 (t, J = 6.9 Hz, 3 H). IR (KBr): 2978, 2208, 1732, 1225 cm-1. ESI-MS: m/z = 252 [M + Na]+. Compound 8a: 1H NMR (200 MHz, CDCl3): δ = 7.73-7.74 (m, 2 H), 7.52 (d, J = 7.6 Hz, 1 H), 7.26-7.33 (m, 1 H), 6.92 (s, 1 H), 4.15 (q, J = 6.8 Hz, 2 H), 2.60-2.76 (m, 4 H), 1.27 (t, J = 6.8 Hz, 3 H). IR (KBr): 2980, 2218, 1733, 1618, 1375, 1218 cm-1. ESI-MS: m/z = 330 [M + Na]+, 332 [M + Na + 2 × H+]. Compound 9a: 1H NMR (400 MHz, CDCl3): δ = 7.59 (d, J = 7.8 Hz, 2 H), 7.19-7.29 (m, 2 H), 6.96 (s, 1 H), 4.15 (q, J = 7.0 Hz, 2 H), 2.70-2.83 (m, 2 H), 2.63-2.67 (m, 2 H), 2.41 (s, 3 H), 1.27 (t, J = 7.0 Hz, 3 H). IR (KBr): 2982, 2209, 1734, 1617, 1375, 1184 cm-1. ESI-MS: m/z = 244 [M + H]+, 266 [M + Na]+.