Cesium carbonate → 1-Methyl-4-[2-methyl-4-nitro-5-(propan-2-yloxy)phenyl]piperazine

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Reaction Steps

24.9 g of caesium carbonate, 745 mg of palladium acetate, 2.88 g of (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane) and 4.89 g of 1-methylpiperazine are added to a solution of 7.62 g of 1-chloro-2-methyl-4-nitro-5-(propan-2-yloxy)benzene (prepared according to WO2008/073687, p. 31) in 380 ml of dioxane under argon. The mixture is refluxed for 5.5 h, and then cooled to ambient temperature. The mixture is combined with the crude product of one and the same reaction carried out on 1.89 g of 1-chloro-2-methyl-4-nitro-5-(propan-2-yloxy)benzene under the same conditions. The mixture is concentrated under vacuum and the residue is taken up with 100 ml of water, 200 ml of ethyl acetate and a little methanol. The mixture is filtered on Clarcel and the aqueous phase is extracted twice with 100 ml of ethyl acetate. The combined organic phases are washed with 100 ml of a saturated sodium chloride solution, dried over magnesium sulfate and concentrated under vacuum. The crude product is purified on 340 g of silica, elution being carried out with 0-100% of acetone in dichloromethane, so as to obtain 5.60 g of 1-methyl-4-[2-methyl-4-nitro-5-(propan-2-yloxy)phenyl]piperazine in the form of a black solid.

Provenance & Evidence