2-Amino-4,5-dimethoxybenzonitrile → Prazosin

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Reaction Steps

To 3.6 g. of 6-aminoveratronitrile, dissolved in 75 ml. of anhydrous benzene, a solution of phenyl lithium (prepared from 0.35 g. of lithium and 3.9 g. of bromobenzene) in 60 ml. of anhydrous diethyl ether is added under a nitrogen atmosphere. After 45 minutes 4.4 g. of 1-cyano-4-(2-furoyl)piperazine in 50 ml. of anhydrous benzene are added. The ether and part of the benzene are distilled off and 100 ml. of tetrahydrofuran are added. The mixture is refluxed under the nitrogen atmosphere for 20 hours and then decomposed with water. The liquid is distilled off and 75 ml. of water are added to the residue. The mixture is extracted with chloroform and the extract is concentrated by evaporation of the solvent. 1-(4-Amino-6,7-dimethoxy-2-quinazolinyl)4-(2-furoyl)piperazine is obtained. The product after crystallization from a mixture of ethanol and water melts at 258°-260°C.

Provenance & Evidence