[C:1]([O:5][C:6]([N:8]([CH3:10])[NH2:9])=[O:7])([CH3:4])([CH3:3])[CH3:2].[F:11][C:12]([F:27])([F:26])[C:13]1[CH:18]=[CH:17][C:16]([C:19]([F:22])([F:21])[F:20])=[CH:15][C:14]=1B(O)O.C(N(CC)CC)C>ClCCCl.C([O-])(=O)C.[Cu+2].C([O-])(=O)C>[C:1]([O:5][C:6]([N:8]([CH3:10])[NH:9][C:14]1[CH:15]=[C:16]([C:19]([F:22])([F:21])[F:20])[CH:17]=[CH:18][C:13]=1[C:12]([F:11])([F:26])[F:27])=[O:7])([CH3:4])([CH3:3])[CH3:2]
A mixture of N-methyl-hydrazinecarboxylic acid tert-butyl ester (Intermediate 1; 600 mg, 3.4 mmol), 2,5-bis(trifluoromethyl)phenylboronic acid (ChemFocus, LLC, East Brunswick, N.J., USA; 953 mg, 3.7 mmol), copper(II) acetate (746 mg, 4.1 mmol) and triethylamine (575 μL, 4.1 mmol) in 1,2-dichloroethane (18 mL) was heated in an oil bath at 50° C. for 2 h. The mixture was allowed to cool, and it was then adsorbed onto silica gel and purified by chromatography using an ISCO 40 g column, eluting with 10% ethyl acetate/hexanes, to give N′-(2,5-bis-trifluoromethyl-phenyl)-N-methyl-hydrazinecarboxylic acid tert-butyl ester (480 mg, 33%) as a colorless oil that solidified.
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