反应详情

13.3 g of 1-benzyl 3-tert.butyl 2-(3-bromo-2-bromomethyl-propanoyl)-hexahydropyridazine-1,3-dicarboxylate in 122 ml of acetic acid and 122 ml of methanol was hydrogenated undera pressure of 1 atmosphere for 16 hours in the presence of 1.4 g of 10% palladium/charcoal, the hydrogenation being carried out under a soda-lime trap. The catalyst was removed by filtration, the filtrate was treated with 3.2 g of sodium acetate trihydrate and then evaporated. The residue was extracted with 300 ml of ethyl acetate and the solution was chromatographed on 400 g of silica gel using diethyl ether/hexane for the elution. There were obtained 1.25 g of tert.butyl 2-bromomethyl-hexahydro-3-oxo-1H-pyrazolo[1,2-a]pyridazine-5-carboxylate (diastereomer A) having a melting point of 109°-111° C. (from hexane), 2.45 g of tert.butyl 2-bromomethyl-hexahydro-3-oxo-1H-pyrazolo[1,2-a]-pyridazine-5-carboxylate (diastereomer B) having a melting point of 88°-89° C. (from hexane) and 1.20 g of a mixture of the aforementioned diastereomers.

1. customThe catalyst was removed by filtration
2. additionthe filtrate was treated with 3.2 g of sodium acetate trihydrate
3. customevaporated
4. extractionThe residue was extracted with 300 ml of ethyl acetate
5. customthe solution was chromatographed on 400 g of silica gel
6. washfor the elution