Fig. 2: Reaction optimization studies^a.

A N-Activating group screening; B Secondary amine evaluation; C Reaction condition optimization; D Investigation into one-pot reactions. ^aYield was determined by ¹H NMR using 1,2-dichloroethane as the internal standard; ^breaction conditions: 3-phenylpyridinium salt (0.1 mmol), pyrrolidine (0.2 mmol), (COCl)₂ (10.0 equiv.), DMF (1.0 mL), CHCl₃ (1.0 mL), 60 °C, 10 h; ^cN-DNP 3-phenylpyridinium salt (0.1 mmol), HNR₂ (0.2 mmol) were used. ^dpyrrolidine (0.02 mmol, 0.2 equiv.) was used; CHCl₃ = chloroform, DMF = N, N-Dimethylformamide.