Regioselective alkylation of 2-phenylpyridines with terminal alkenes via C–H bond activation by a rhodium catalyst

2-Phenylpyridine 1a reacts with various terminal alkenes in the presence of a rhodium(I) complex catalyst to give the corresponding mono ortho-alkylated products 2a–i and doubly alkylated products 3a–b (9:1). The same reaction using 3-methyl-2-phenylpyridine 1b gives the mono alkylated products 2j–n exclusively under the same reaction conditions due to steric hindrance between the methyl group of the pyridine and the alkyl group of 2j–n.