HIGH TEMPERATURE HECK COUPLING.doc

High temperature Heck coupling of (2-bromo-5-methoxy-3-methylphenyl)-acetonitrile with ethyl acrylate.; 3-(2-cyanomethyl-4-methoxy-6-tolyl)-acrylic acid ethyl ester SyntheticPage 173 (2001)Submitted 27th Nov 2001, published 27th Nov 2001 lisa frost ( HYPERLINK mailto:kafs4@sussex.ac.uk kafs4@sussex.ac.uk),A contribution from the Caddick Group, Sussex Chemicals Used(2-bromo-5-methoxy-3-methylphenyl)-acetonitrile HYPERLINK /pages/172 [SyntheticPage 172] Palladium dichloride-bis-triphenylphosphine (Aldrich) Tri-o-tolylphosphine HYPERLINK /pages/170 [SyntheticPage 170] Triethylamine (distilled from CaH2) Ethyl acrylate (Lancaster) Toluene (distilled from sodium) ProcedureIn a high pressure vessel was placed 2-bromo-5-methoxy-3-methylphenyl)-acetonitrile (17.6 g, 73 mmol, 1 equiv), Pd(PPh3)2Cl2 (2.57 g, 3.67 mmol, 5 mol%), P(o-tolyl)3 (3.35 g, 11 mmol, 15 mol%), ethyl acrylate (8.8 g, 88 mmol, 1.2 equiv), triethylamine (11.1 g, 110 mol, 1.5 equiv) and toluene (22 mL/g nitrile). The vessel was purged with nitrogen, sealed and slowly cooled to -78 oC. The vessel was evacuated at this temperature, sealed and allowed to slowly warm to room temperature. The vessel was then heated to 165 oC for 16 h, after which it was allowed to cool to room temperature and was washed with water (200 mL). The organics were extracted into ether (3 x 200 mL)and washed with a further portion of water (100 mL). The combined organics were dried over MgSO4, filtered and concentrated in vacuo. The resulting brown oil was purified by column chromatography on silica gel with petrol:ethyl acetate (5:1 v:v) as the eluent yielding the title compound as a yellow solid (9.0 g, 48%) Authors CommentsThe glass vessel used in this reaction was basically a schlenk tube (or ampule) fitted with a youngs tap. The tube was made from thick glass able to withstand moderate pressures. This reaction seems low yielding, but the yield can vary from 75% to 30% depending on i. catalyst purity, ii. turnover iii. re