[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([NH:8][C@H:9]([C:13]([OH:15])=[O:14])[CH:10]([CH3:12])[CH3:11])=[CH:4][CH:3]=1.CN(C1C=CC=CN=1)C.[Cl:25][C:26]([Cl:31])([Cl:30])[C:27](Cl)=[O:28].CCOCC.O>CCOCC>[Cl:25][C:26]([Cl:31])([Cl:30])[C:27]([N:8]([C:5]1[CH:4]=[CH:3][C:2]([Cl:1])=[CH:7][CH:6]=1)[C@H:9]([C:13]([OH:15])=[O:14])[CH:10]([CH3:12])[CH3:11])=[O:28]To the m-phenoxybenzyl ester of N-(4-chlorophenyl)valine (1.19 mmole) in ether (4.5 ml), under nitrogen, is added dimethylaminopyridine (4.25 mmole) which is cooled in an ice-bath and then trichloroacetyl chloride (3.58 mmole) in ether added slowly. The reaction mixture is heated at 40° for 3 days. The reaction is worked up with ether/water. The aqueous phase is extracted with ether and then the combined ether phases are washed with water and brine and dried over sodium sulfate. The residue is subjected to prep. TLC eluting with 10% ether/hexane to yield the m-phenoxybenzyl ester of N-trichloroacetyl,N-(4-chlorophenyl)valine. MS m/e 553 (M+, 1.8), 183 (100).
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