3-Chloro-2-hydrazinylpyridine → Ethyl 1-(3-chloropyridin-2-yl)-5-hydroxy-3-(hydroxymethyl)-4,5-dihydro-1H-pyrazole-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

The mixture of ethyl (3E)-3-(2,2-dimethyl-1,3-dioxolan-4-ylidene)-2-oxopropanoate (21.4 g, 0.1 mol) and 2-hydrazino-3-chloropyridine (14.3 g, 0.1 mol) in 50 ml of ethanol was stirred for 18 hours at 35° C. Ethanol was removed in vacuo and the residue was taken up in 100 ml of methyl (tert)-butyl ether. The organic phase was washed once with 50 ml of 1% strength HCl and concentrated by evaporation. This gave 26.2 g (86% yield) of the product as a viscous oil with a purity (HPLC) of 97%.

Provenance & Evidence