Emergence of Unactivated Olefins for the Synthesis of Olefinated Arenes

Mizoroki-Heck olefination is one of the most exquisite methods for making carbon-carbon bonds. Numerous methods have been reported for olefination with electronically biased olefins such as acrylates and styrenes. In the absence of suitable bias, olefination with unactivated olefins suffers from regioselectivity issues. Because of these problematic regio-chemical outcomes, there are only scattered examples of olefination with unactivated olefins. Both linear-selective and branched-selective protocols, based on control over the selectivity of olefin insertion and beta-hydride elimination, have been reported. In this microreview, different branched-selective and linear-selective olefination protocols with unactivated olefins are discussed, starting from the invention of Heck olefination. Throughout this microreview, different aspects associated with olefination protocols - such as the factors underlying selectivity, functional group tolerance and, more specifically, the use of a variety of unactivated olefins - are discussed.