Ammonium Chloride → 1-(3-Hydroxybutan-2-yl)-4-(4-(4-(4-hydroxyphenyl)piperazin-1-yl)phenyl)-1H-1,2,4-triazol-5(4H)-one

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Reaction Steps

A mixture of (±)-2,4-dihydro-4-[4-[4-(4-hydroxyphenyl)-1-piperazinyl]phenyl]-2-(1-methyl-2-oxopropyl)-3H-1,2,4-triazol-3-one (0.120 mol) in DMF (700 ml) was cooled on ice. Potassium tri-sec-butylborohydride, 1M solution in THF (300 ml) was added dropwise. The mixture was allowed to warm to room temperature, then poured out into an aqueous NH4Cl solution. The precipitate was filtered off, dried and crystallized from 2-propanol. This fraction was separated into its enantiomers over CHIRALPAC AD [(amylose 3,5 dimethylphenyl carbamate) purchased from Daicel Chemical Industries, Ltd, in Japan] (eluent: 100% ethanol). Two pure fraction groups were collected and their solvent was evaporated. The desired fraction was recrystallized from methanol. The precipitate was filtered off and dried, yielding 0.9 g of [R-(R*,R*)]-2,4-dihydro-2-(2-hydroxy-1methylpropyl)-4-[4-[4-(4-hydroxyphenyl)-1-piperazinyl]phenyl]-3H-1,2,4-triazol-3-one (interm. 14a; [α]20D=+10.35° @ 48.61 mg/5 ml in DMF) and 0.8 g [S-(R*,R*)]-2,4-dihydro-2-(2-hydroxy-1-methylpropyl)-4-[4-[4-(4-hydroxyphenyl)-1-piperazinyl]phenyl]-3H-1,2,4-triazol-3-one (interm. 14b).

Provenance & Evidence