Search

Nickel-catalyzed anti-selective alkyne functionalization reactions are reviewed with an emphasis on the mechanisms that lead to their observed stereoselectivity. Since the isomerization of alkenylnickel species plays a key role in a large number of these reactions, the potential mechanisms for these processes are also described in detail.1 Introduction2 anti-Selective Hydroarylation3 anti-Selective Carboborylation4 anti-Selective Dicarbofunctionalization4.1 Carbocyanative Cyclization4.2 Cyclization with Aryl Donors4.3 Cyclization with CO2 4.4 Intermolecular Dicarbofunctionalization5 anti-Selective Carbosulfonylation6 Alkenylnickel Isomerization7 Conclusions

An operationally simple nickel-catalyzed hydroarylation reaction for alkynes is described. This three-component coupling reaction utilizes commercially available alkynes and aryl bromides, along with water and Zn. An air-stable and easily synthesized Ni(II) precatalyst is the only entity used in the reaction that is not commercially available. This reductive cross-coupling reaction displays a fairly unusual anti selectivity when aryl bromides with ortho substituents are used. In addition to optimization data and a preliminary substrate scope, complementary experiments including deuterium labeling studies are used to provide a tentative catalytic mechanism. We believe this report should inspire and inform other Ni-catalyzed carbofunctionalization reactions.

Herein is presented a direct method for the metal-free hydrotrifluoromethylation of alkenes. The method relies on the single electron oxidation of a commercially available sodium trifluoromethanesulfinate salt (CF3SO2Na, Langlois reagent) by N-Me-9-mesityl acridinium as a photoredox catalyst. Methyl thiosalicylate is used as a substoichiometric H-atom donor for aliphatic alkenes, and thiophenol is used as a stoichiometric H-atom donor for styrenyl substrates. The substrate scope for the transformation is broad, including mono-, di- and trisubstituted aliphatic and styrenyl alkenes, with high regioselectivity in nearly all cases examined.