trifluoroacetic acid T=20°C; 2 h;

1: 3-bromo-5-pyridine-carboxylic acid With benzotriazol-1-ol; Wang resin; diisopropyl-carbodiimide in N,N-dimethyl-formamide 2: 3,4-(methylenedioxy)phenylboronic acid With potassium phosphate; tetrakis(triphenylphosphine) palladium(0) in N,N-dimethyl-formamide T=80°C; Suzuki coupling reaction; 24 h; 3: With trifluoroacetic acid in dichloromethane 0.333333 h;