An improved multigram synthesis of tetradeuterated buspirone

A simple, convenient and efficient two step method for the synthesis of bus pirone-d(4) hydrochloride 4 from the commercially available materials is de scribed. Tetramethylene glutarimide 1 was first N-alkylated with 1,4-dibrom obutane-2,2,3,3-d(4) 2 to give a monoalkylated compound 3 which was transfo rmed to buspirone-d(4) by alkylation with 1-(2-pyrimidyl)piperazine. This i mportant antianxiety compound obtained in 63% yield having isotopic purity similar to 96% should prove useful in carrying out bioavailability studies.