SYNTHESIS OF BICYCLIC GUANIDINES
3687
methanol. Then 30 ml of methylene chloride was added. Sodium chloride was filtered
off, and methylene chloride solution was evaporated, first in a rotary evaporator,
then under high vacuum (<5 Torr for 1–3 h) at 90 ꢀC. Yield: 12.9 g (93%) of slightly
yellow=off-white soft solid material. 1H NMR (D2O, 400 MHz, 25 ꢀC) d 3.207 (t, 4H,
1J ¼ 6.0 Hz); 3.270 (t, 4H, 1J ¼ 6.0 Hz); 1.959 (p, 4H, 1J ¼ 6.0 Hz). Estimated purity is
95–97% as calculated by comparison of TBD resonance at 1.96 ppm versus impurity
signals at 1.84 and 1.7 ppm.
In the case of experiments where TsOH or MsOH acids were used, the acids
were added slowly after guanidine carbonate or cyanamide have been mixed
with triamine. Guanidine hydrobride was made by slow addition of aquavious
hydrobromic acid to guanidine carbonate followed by evaporation under vacuum.
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