Fig. 2: Optimization of the reaction conditions.

aReaction conditions: 1a (0.2 mmol), 2a (0.2 mmol), PdCl2(10 mol%), L1 (20 mol%), NaBArF4 (30 mol%), 2,5-DTBQ (1.5 equiv.), and Al2O3 (60 mg) in DCM (0.1 M) at 70 oC under N2 atmosphere for 72 h. bYield was determined by 1H NMR of the crude product using CH2Br2 as internal standard. cIsolated yield. ArF = 3,5-(CF3)2C6H3. 2,5-DTBQ = 2,5-di-tert-butylcyclohexa-2,5-diene-1,4-dione.