in o-xylene T=20 - 142°C; 40 h; Heating / reflux;

1: With N,N-dimethyl-cyclohexylamine T=155°C; 58 h; 2: With hydrogenchloride in dichloromethane; water 1.5 h; Heating / reflux; 3: With sodium hydroxide in water pH=13 - 14;