Substrate scope of urea derivatives 1 in the manganese-catalyzed transfer hydrogenation^a.

^aReaction conditions: substrates 1a–1l (0.5 mmol), Mn–IV (2 mol%), KOtBu (6 mol%), toluene (1 mL), iPrOH (1 mL), 120 °C, 16 h. The yield was determined by GC using mesitylene as the internal standard. Isolated yields are given in brackets.

^b50 mmol 1a, 30 h.

^c36 h.