*3.6. Generation of the Free Base of Papaverine (1b)*

Papaverine hydrochloride (**1a**, 200 mg) was dissolved in a mixture of ammoniated H2O (9:1, H2O:28% aq. NH3, 20 mL) and then extracted with CH2Cl2 (3 × 20 mL). The free base of papaverine (**1b**) was soluble in the CH2Cl2 layer, and following evaporation, yielded the desired product with a high purity and yield (174 mg, 93%).
