Guanidine → 2-Di-n-propylamino-8-(2-aminopyrimidin-4-yl)-1,2,3,4-tetrahydronaphthalene

2-Di-n-propylamino-8-(1-oxo-3-(dimethylamino)-prop-2-enyl)-1,2,3,4-tetrahydronaphthalene, prepared as in Example 8 (0.18 g; 0.55 mmol) was dissolved in 3 ml of ethanol. To the mixture was added 0.07 g (1.1 mmol) of guanidine, and the mixture was stirred at 60° C. under nitrogen for 18 hours. The mixture then was cooled to room temperature during which a crystalline solid formed. The crystals were filtered, washed with isopropyl alcohol, ether, and dried in vacuo to give 70 mg of the title compound as glistening plates. The product was recrystallized from isopropyl alcohol to obtain colorless crystals, m.p. 188°-189° C. Analysis: Theory: C, 74.04; H, 8.70; N, 17.27; Found: C, 74.30; H, 8.70; N, 17.45.