Methanesulfonic Acid → 7,8-dihydro-1,3-dimethyl-1H-imdazo[1,2-c]pyrazolo[3,4-e]pyrimidine

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Reaction Steps

The above nitro compound (8.4 g, 0.04 mol) is dissolved in 150 ml of methanol and hydrogenated (initial hydrogen pressure=51 psi) in the presence of 0.5 g of Raney nickel until the theoretical uptake of hydrogen is observed. The catalyst is removed by filtering; the filtrate is evaporated in vacuo to give 7.4 g (0.04 mol) of a purple oil (characterized by its IR-spectrum) of 2-(4-amino-1,3-dimethyl-5-pyrazolyl)imidazoline. This amine (7.4 g, 0.04 mol) is stirred under reflux 1.5 hr in a mixture of 20 ml absolute ethanol, 50 ml of triethylorthoformate and 1 ml of methanesulfonic acid. The mixture is evaporated in vacuo. The product is dissolved in methylenedichloride (100 ml) and washed with 100 ml of dilute ammonium hydroxide; the organic layer is dried over MgSO4 and evaporated in vacuo to give 7,8-dihydro-1,3-dimethyl-1H-imdazo[1,2-c]pyrazolo[3,4-e]pyrimidine 1.5 hydrate, mp 80°-82° C. from ethyl acetate-pet ether.

Provenance & Evidence