Phenylbutazone → 1,2-Diphenyl-4-butyl-4-pivalyloxymethyl-3,5-pyrazolidinedione

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Reaction Steps

Potassium carbonate (2.26 g, 0.016 mole) was suspended in an acetone (125 ml) solution of phenylbutazone and the suspension was refluxed overnight. The next day pivalyloxymethyl chloride (4.99 g, 0.033 mole) was added to the resulting solution and the solution was refluxed overnight. The suspension was cooled and filtered; the residue (2.00 g, 83%) was potassium chloride. The filtrate was concentrated in vacuo and the residue was suspended in ether, then filtered. The residue was washed with ether until the washings did not contain any product by TLC. The residue from the ether suspension was the potassium salt of phenylbutazone (2.25 g, 20%). The ether was then concentrated in vacuo and the residue was absorbed on silica gel and chromatographed on neutral silica gel (CC-7, Mallinckrodt) using petroleum ether bp 30°-60° C. -- ether (1:1) as the eluent to give two fractions. The first fraction (Rf 0.46, silica gel, heptane-ether, 1:1) was crystallized from heptane-petroleum ether bp 30°-60° C., 1:1 to give 0.63 g (mp 116°-117° C., 5% yield) of 1,2-diphenyl-4-butyl-4-pivalyloxymethyl-3,5-pyrazolidinedione. nmr (CDCl3) δ 4.40 (S, 2) ##STR13##

Provenance & Evidence