4-Hydroxybenzoic acid hydrazide → 4-(5-{[4-Chloro-3-(trifluoromethyl)-phenyl]amino}-1,3,4-oxadiazol-2-yl)phenol

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Reaction Steps

Mercury (II) oxide (yellow) (4.55 g, 21.0 mmol) was suspended in 60 mL of anhydrous MeOH under Ar. A bright-orange suspension was formed. To this suspension was added 4-hydroxybenzoic acid hydrazide (3.20 g, 21.0 mmol) and 4-chloro-3-trifluoromethyl-phenylisothiocyanate (5.0 g, 21.0 mmol). The reaction mixture was refluxed for 2 hours. The solvent was removed in vacuo. The black residue was redissolved in 100 mL of EtOAc and the resulting black suspension was filtered through a short pad of silica gel. The filtrate was mixed with 10 g of dry silica gel and solvent was removed in vacuo. The impregnated silica gel was loaded on silica gel column and the product was separated using a gradient of hexane:ethyl acetate mixture starting from 50:50 ratio and finishing at 0:100. All fractions containing the product were combined; solvent was removed in vacuo to give a grey solid. The solid was heated in 50 mL of 4:1 mixture of EtOAc/MeOH. The formed suspension was cooled down to ambient temperature and filtered to give the title product as a white crystalline solid (4.54 g, 60.7% yield).

Provenance & Evidence