18-Crown-6 → HCID 58524147, compound

Participants

Reaction Steps

A solution of methyl 3,4-dimethyl-2-aminobenzoate (10 g) in concentrated hydrochloric acid (20 ml) was cooled to 0° C., treated with solution of tetrafluoroammoniumborate (9.4 g) in water (2 ml), a solution of sodium nitrite (7.7 g) in water (2 ml) dropwise, stirred for 2 h, filtered to get a solid. The solid residue was dissolved in chloroform (50 m), treated with potassium acetate (2 mol equivalents) and catalytic amounts of 18-Crown-6, and stirred for 12 h. The reaction mixture was treated with water (50 ml) and extracted with chloroform (2×50 ml). The combined organic layers were dried over sodium sulfate and concentrated. Chromatographic purification (hexane/ethyl acetate 80:20) gave 4-methyl- 1H-indazole-7-carboxylic acid methyl ester (3.2 g). 1H-NMR (400 MHz, CDCl3): 2.68 (s, 3H), 4.00 (s, 3H), 7.02 (d, 1H), 7.97 (d, 1H), 8.15 (s, 1H). LC-MS (methanol): m/z=191 (M+H).

Provenance & Evidence