Reaction of o-phenylenediamine with aldehydes^a.

^aReaction conditions: 1a (0.2 mmol), 2a (0.5 mmol), 4 (0.4 mmol), 4-ADPA (0.2 mmol), paraformaldehyde (0.5 mmol), TCE (0.7 mL), H₂O (0.2 mL), 100 °C, 3 h, air. Isolated yield.