Triphenylphosphine → 4-(4-Chloro-5-methyl-2-nitro-phenoxy)-piperidine-1-carboxylic acid tert-butyl ester

Beteiligte Stoffe

Reaktionsschritte

To a mixture of 4-Chloro-5-methyl-2-nitro-phenol (3.752 g, 20.0 mmol), 4-Hydroxy-piperidine-1-carboxylic acid tert-butyl ester (4.83 g, 24 mmol), and triphenylphosphine (6.23 g, 24 mmol) in 75 mL THF is added diisopropyl asodicarboxylate (4.73 mL, 245 mmol) in several portions at 22° C. for 1 h. The reaction is stirred at the same temperature for an additional 2 hrs. The reaction mixture is concentrated in vacuo. The residue is taken up in 50 mL ether, and let stand at 22° C. for 14 hrs. The resulting crystals are removed by filtration. The filtrate is concentrated in vacuo, and the residue is purified over a 330 g SiO2 column (ISCO) using a gradient of 20 to 40% ethyl acetate in hexanes as eluent, affording 4-(4-Chloro-5-methyl-2-nitro-phenoxy)-piperidine-1-carboxylic acid tert-butyl ester as dark yellow viscous oil. MS (ES+); 315.1 (MH+-C4H8), 393.1 (MNa+).

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