Transition-metal-free Coupling Reactions of Aryl Halides

Transition metal catalysis plays a leading role in C(sp(2))-C(sp(2)) bond formation through substitution reactions. On the other hand, a similar type of substitution reaction has recently been achieved without the aid of transition-metal catalysts. In this review, recent transition-metal-free coupling reactions of aryl halides with arenes, alkenes, or aryl Grignard reagents are summarized in view of S(RN)1 reaction.