Sodium → 4-(2-chloro-5-fluorobenzyl)-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one

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Reaction Steps

To a solution of MeONa (0.82 M) in methanol (200 mL), freshly prepared from sodium (3.80 g, 165 mmol) and dry methanol (200 mL), was added methyl 2-(2-(2-chloro-5-fluorobenzylcarbamothioyl)hydrazono)propanoate (28, 10.00 g, 31.5 mmol). The mixture was heated at reflux for 36 h. Most of the solvent was evaporated. The resulting residue was diluted with water (300 mL), acidified with 2 N HCl to pH=1˜2, and then extracted with EtOAc (250 mL×2). The extracts were washed with brine, dried over MgSO4, and concentrated to give a mixture, which was separated by silica gel column, and eluted with 20-30% ethyl acetate in petroleum ether to give 4-(2-chloro-5-fluorobenzyl)-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one (29).

Provenance & Evidence