BrC[C:3]1[CH:4]=[C:5]([C:11]2[CH:16]=[CH:15][C:14]([Cl:17])=[CH:13][C:12]=2[Cl:18])[CH:6]=[CH:7][C:8]=1[CH2:9]C.[C:19]([O-])(=[S:21])[CH3:20].[K+].C(=O)([O-])[O-].[K+].[K+].[CH2:30]([O:32][C:33]([C:35]1[C:40]([CH2:41]Br)=[N:39][CH:38]=[CH:37][N:36]=1)=[O:34])[CH3:31]>C(O)C>[CH2:30]([O:32][C:33]([C:35]1[C:40]([CH2:41][S:21][CH2:19][C:20]2[CH:7]=[CH:6][C:5]([C:11]3[CH:16]=[CH:15][C:14]([Cl:17])=[CH:13][C:12]=3[Cl:18])=[CH:4][C:3]=2[CH2:8][CH3:9])=[N:39][CH:38]=[CH:37][N:36]=1)=[O:34])[CH3:31]To a solution of 3′-bromomethyl-2,4-dichloro-4′-ethyl-biphenyl (1 g) in ethanol (10 ml) was added potassium thioacetate (1.1 g, Aldrich 241776) and the mixture stirred for 1 hr. To this mixture was added potassium carbonate (0.442 g) and stirring was continued for a further hour. A solution of 3-bromomethyl-pyrazine-2-carboxylic acid ethyl ester (0.712 g) in ethanol (3 ml) was added to the reaction mixture and the reaction was stirred for a further 18 hr. The reaction was partitioned between chloroform and water. The organic layer was concentrated and the residue purified by chromatography on silica gel (eluent: 0-20% v/v ethyl acetate in dichloromethane) to give a 30% pure sample of 3-(2′,4′-dichloro-3-ethyl-biphenyl-4-ylmethylsulfanylmethyl)-pyrazine-2-carboxylic acid ethyl ester contaminated with 3-bromomethyl-pyrazine-2-carboxylic acid ethyl ester (0.300 g). MH+=461, RT=2.25 min (Method A).
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