8-Azaspiro(4.5)decane-7,9-dione → Buspirone

Participants

Reaction Steps

A solution of 100 g (0.26 mole) of 8-[4-[4-pyrimidine-2-yl)-piperazine-1-yl]-but-2-inyl]-8-aza-spiro[4.5]decane-7,9-dione in 50 ml of tetrahydrofurane is added to a suspension of 1 g of a palladium/carbon catalyst (palladium content about 5% by weight) and 50 ml of tetrahydrofurane under vigorous stirring under the introduction of hydrogen under a pressure of 2 bar at such a rate that the hydrogen uptake of the unsaturated 8-[4-[4-(pyrimidine-2-yl)-piperazine-1-yl]-but-2-inyl]-8-aza-spiro[4.5]decane-7,9-dione added is substantially identical with the calculated hydrogen consumption. This means practically that when the addition of the starting material is stopped, the decrease of the hydrogen pressure in the apparatus ceases within 5-10 seconds. The addition of the starting material takes 1-4 hours, depending on the intensity of stirring. The reaction temperature is adjusted to 15°-30° C. during the complete period of addition. At the end of hydrogenation the catalyst is filtered off. The catalyst can be directly used in the next hydrogenating operations without any further treatment. The filtrate is evaporated, the residue is suspended in isopropanol and filtered. Thus in the form of white crystals 99.7 g of 8-[4-[4-(pyrimidine-2-yl)-piperazine-1-yl]-butyl]-8-aza-spiro[4.5]decane-7,9-dione are obtained, yield 98.7%. Melting point: 105°-106° C. (according to prior art 90°-98° C.). Content (on the base): 99.8-100.1%. According to HPLC analysis the product contains only 0.1% of contaminations.

Provenance & Evidence