Ethoxalyl chloride → Ethyl 7-bromo-(1,2,4)triazolo(1,5-a)pyridine-2-carboxylate
Reaction equation
CC1C=C(C)C=C(C)C=1S([O-])(=O)=O.[NH2:14][N+:15]1[CH:20]=[CH:19][C:18]([Br:21])=[CH:17][C:16]=1[NH2:22].Cl[C:24](=O)[C:25]([O:27][CH2:28][CH3:29])=[O:26]>N1C=CC=CC=1>[Br:21][C:18]1[CH:19]=[CH:20][N:15]2[N:14]=[C:24]([C:25]([O:27][CH2:28][CH3:29])=[O:26])[N:22]=[C:16]2[CH:17]=1Participants
4
Procedure
A mixture of 1,2-diamino-4-bromopyridinium 2,4,6-trimethylbenzenesulfonate (4.18 g, 10.8 mmol) and ethyl 2-chloro-2-oxoacetate (2.4 ml, 21.5 mmol) in pyridine (25 ml) is heated for 18 hours to 100° C. The solvent is evaporated and the orange residue triturated with sat. aqueous sodium hydrogencarbonate solution for 2 hours. The solid is collected by filtration, washed several times with water and dried affording ethyl 7-bromo-[1,2,4]triazolo[1,5-a]pyridine-2-carboxylate (1.759 g, 60.5%) as a light pink solid. mp.: 158-160° C. MS: m/z=270.2 (M+H+).