p-Toluenesulfonic acid monohydrate → 4-(4-bromo-2-methylbenzylidene)-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-5(4H)-imine

Participants

Reaction Conditions

Reaction Steps

A suspension of 1-methyl-3-(pyridin-2-yl)-1H-pyrazol-5-amine (4.50 g, 25.8 mmol, Example #2 step B), 4-bromo-2-methylbenzaldehyde (5.14 g, 25.8 mmol, Astatech) and 4-methylbenzenesulfonic acid hydrate (0.491 g, 2.58 mmol) in MeCN (36 ml) was warmed up to about 45° C. for about 15 min to give a solution then the reaction was allowed to cool to rt. The precipitate was filtered and washed with MeCN to give 4-(4-bromo-2-methylbenzylidene)-1-methyl-3-(pyridin-2-yl)-1H-pyrazol-5(4H)-imine (5.88 g, 16.55 mmol, 64%) as a beige solid: LC-MS (Table 1, Method g) Rt=2.55 min, m/z 355/357 (M+H)+; 1H-NMR (DMSO-d6, Bruker 400 MHz) δ 9.07 (s, 1H), 8.60-8.57 (m, 1H), 8.02-7.95 (m, 2H), 7.91-7.86 (m, 1H), 7.61-7.50 (m, 2H), 7.40-7.31 (m, 1H), 7.19 (s, 1H), 3.96 (s, 3H), 2.62 (s, 3H).

Provenance & Evidence