Potassium Hydroxide → HCID 23680078, compound

Participants

Reaction Steps

A mixture of 1.84 g (3.92 mmol) of the preceding ester and 4.71 ml of 1 N KOH in 10 ml of tetrahydrofuran-ethanol (1:1) was refluxed overnight and the solvent removed under vacuum. The residue was triturated with diethyl ether and filtered to give 1.59 g of potassium 4-{methyl-[4-(4-pyridinyloxy)benzene-sulfonyl]amino}-3-methylisoxazolo[5,4-b]pyridine-5-carboxylate as a pale yellow solid. Following the procedure of Example 91, the preceding potassium salt (1.45 g) was reacted with hydroxylamine to give a solid. The solid was partitioned between 30 ml of CH2Cl2 and 30 ml of H2O and filtered. The CH2Cl2 layer was stirred with 2 N citric acid (aqueous phase-pH 6). The solid which precipitated was filtered off and suspended in H2O. The aqueous suspension was adjusted to pH 7 with 1 N NaHCO3 and filtered. The solid was again suspended in H2O and the pH of the aqueous suspension adjusted to pH 6 with 2 N citric acid. The mixture was stirred and filtered to give 0.66 g of 4-{methyl-[4-(4-pyridinyl-oxy)benzenesulfonyl]amino}-3-methylisoxazolo[5,4-b]pyridine-5-carboxylic acid, hydroxyamide, m.p. 141° C. dec.

Provenance & Evidence