p-Toluenesulfonic acid → 7,8-Dihydro-1,3,5,7,7-pentamethyl-1H-imidazo[1,2-c]pyrazolo[3,4-e]pyrimidine

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Reaction Steps

The requisite 2-(4-amino-1,3-dimethyl-5-pyrazolyl)-3,3-dimethylimidazoline is prepared as follows. p-Toluenesulfonic acid (10 g, 0.055 mol) is added to 5 g (0.057 mol) of 1,2-diamino-2-methylpropane and to the resulting hot (100°) melt is added 7 g (0.05 mol) of 4-amino-5-cyano-1,3-dimethylpyrazole. The mixture is heated in an oil bath at 185°-195° C. for six hours. The residue, an amorphous yellow solid is dissolved in 250 ml of chloroform and stirred with 40 ml of conc. ammonium hydroxide. The organic layer is separated, dried (MgSO4), and evaporated in vacuo to give 9 g (90%) of slightly crude title compound as a viscous purple oil.

Provenance & Evidence