[CH2:1]([C:3]1[CH:8]=[CH:7][C:6]([OH:9])=[CH:5][CH:4]=1)[CH3:2].B(Cl)(Cl)Cl.CS[C:16]#[N:17].[Cl-].[Al+3].[Cl-].[Cl-].[OH-].[Na+]>ClCCl>[C:16]([C:5]1[CH:4]=[C:3]([CH2:1][CH3:2])[CH:8]=[CH:7][C:6]=1[OH:9])#[N:17]
A solution of 4-ethylphenol (2.44 g) in dichloromethane (10 ml), was added to a stirred, ice-cooled, solution of 1M boron trichloride in dichloromethane (24 ml) under argon, followed by methylthiocyanate (1.64 ml), and then anhydrous aluminium chloride (2.66 g). The mixture was stirred for 1 hour at 4° C., then heated at reflux (bath temperature 60° C.) for 4 hours and finally stirred for 16 hours at ambient temperature. The mixture was added cautiously to a stirred, ice-cooled, 4M sodium hydroxide solution and the resultant mixture heated at 70° C. for 30 minutes then cooled. The aqueous phase was separated, washed with dichloromethane (2×25 ml), then acidified to pH 2 with 6M hydrochloric acid and extracted with ethyl acetate (3×75 ml). The combined organic extracts were washed with saturated brine (3×50 ml), dried (MgSO4) and the solvent removed in vacuo to give a brown solid. Purification by flash chromatography, eluting with 20% v/v ethyl acetate in hexane, followed by recrystallisation from hexane gave 2-cyano-4-ethylphenol (A) (2.56 g), m.p. 95°-98° C.; NMR: 1.21 (3H, t, J=7 Hz), 2.59 (2H, q, J=7 Hz), 5.70 (1H, b), 6.90 (1H, m), 7.29 (2H, m).
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