Potassium Carbonate → {(3R*,5S*)-5-[Cyclopropyl-(2,3-dimethyl-benzyl)-carbamoyl]-piperidin-3-yl}-carbamic acid tert-butyl ester

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Reaction Steps

To a stirred, ice-cooled mixture of (3S*,5R*)-5-tert-butoxycarbonylamino-piperidine-1,3-dicarboxylic acid 1-(9H-fluoren-9-ylmethyl) ester (5.0 g, 10.7 mmol), cyclopropyl-(2,3-dimethyl-benzyl)-amine (CAS 625437-38-9) (4.41 g, 11.8 mmol) and N-ethyldiisopropylamine (14.7 ml, 85.7 mmol) in dimethylacetamide (50 ml), propylphosphonic anhydride solution (˜50% in DMF, 10 ml, ˜16 mmol) is added. After stirring for 14 h at RT, the residue is distributed between ethyl acetate and 10% aqueous K2CO3 solution. The organic layer is dried (Na2SO4) and evaporated in vacuo. Part of the residue (365 mg, 0.58 mmol) is treated with a mixture of CH2Cl2/piperidine (4:1; 10 ml) and stirred at RT for 1 h. The reaction mixture is then evaporated and the residue purified via preparative HPLC to afford the title compound. MS: 402.5 [M+H]+; tR (HPLC, Nucleodur 100; 10-100% CH3CN+0.1% TFA/H2O+0.1% TFA for 10 min, flow 1.5 ml/min): 4.77 min.

Provenance & Evidence