2-Ethyl-5-phenyl-2H-pyrazole-3-carboxylic Acid Methoxy-methyl-amide → [4-(2-Ethyl-5-phenyl-2H-pyrazol-3-yl)-4-oxo-but-2-ynyl]-carbamic Acid Tert-Butyl Ester

Participants

Reaction Conditions

Reaction Steps

To a −10° C. solution of N-t-butoxycarbonyl propargylamine (502 mg, 3.24 mmoles) in THF (5 mL) was added nBuLi (3.7 mL of a 1.6 M solution in hexanes, 5.94 mmoles) dropwise over 10 minutes. The resulting dianion mixture was stirred at −10° C. for 15 minutes, then treated with a THF solution (2 mL) of the above-prepared 2-ethyl-5-phenyl-2H-pyrazole-3-carboxylic acid methoxy-methyl-amide (125 mg, 482 μmoles), allowed to warm to room temperature, and stirred at room temperature for 2 hours. The resulting mixture was cooled to 0° C., quenched with 2 M NaH2PO4, diluted with ethyl acetate, and vigorously stirred for 5 minutes. The phases were separated, the organic phase dried over Na2SO4, filtered, and concentrated in vacuo. The crude title compound was used directly in the next step.

Provenance & Evidence