On the other hand, the reaction outcome strongly depended on the nature of the heterocyclic partner: the highest average yields were observed for 4-methylquinoline 1{1} (69%), and the lowest -for benzothiazole 1{5} (37%) (Figure ). The latter fact can be rationalized by limited stability of benzothiazole toward radical oxidants (including Ag + /S2O8 2-system). Interestingly, trifluoroborates 2 worked better with this particular heterocycle as compared to carboxylic acids 3 (almost 20% higher average product yield).