Ethyl 5-oxo-1-phenyl-4,5-dihydro-1H-pyrazole-3-carboxylate → 3H-Pyrazol-3-one, 2,4-dihydro-2,5-diphenyl-

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Reaction Conditions

Reaction Steps

A mixture of 2,4-dihydro-2-phenyl-5-ethoxycarbonyl-3H-pyrazol-3-one (10 g; 43 mmol) and 1-(2-aminoethyl)pyrrolidine (10 ml) was heated at 130° C. under nitrogen for 2 hours and cooled. The mixture was triturated in hexane, filtered and the solid was washed with hexane to yield 15 gm of a crude product. A portion (8.6 g ) of the crude product was purified by column chromatography (silica gel, triethylamine:methanol:methylene chloride 1:9:90) to afford 5.04 g of 2,4-dihydro-2-phenyl-5-[C(O)NH(CH2)2 -1-pyrrolidinyl]-3H-pyrazol-3-one (Formula III: R1 =Ph; R2 =C(O)NH(CH2)2 -1-pyrrolidinyl; R3 =H) as a tan solid, which was further crystallized in toluene/methanol (2×) to yield a white solid, m.p. 210°-211° C.

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