Transition-Metal-Catalyzed C–H Alkylation Using Alkenes

Abstract

Alkylation reactions represent an important organic transformation to form C-C bonds. In addition to conventional approaches with alkyl halides or sulfonates as alkylating agents, the use of unactivated olefins for alkylations has become attractive from both cost and sustainability viewpoints. This Review summarizes transition-metal-catalyzed alkylations of various carbon-hydrogen bonds (addition of C-H bonds across olefins) using regular olefins or 1,3-dienes up to May 2016. According to the mode of activation, the Review is divided into two sections: alkylation via C-H activation and alkylation via olefin activation.

Palladium(I) Dimer Enabled Extremely Rapid and Chemoselective Alkylation of Aryl Bromides over Triflates and Chlorides in Air

“…[1] While remarkable progress has been made with transition-metal catalysis, [2] Pd-based methodology frequently offers superior generality and mildness-a prerequisite to access richly functionalized building blocks for further synthetic transformations.…”

The Use of a Rhodium Catalyst/8-Aminoquinoline Directing Group in the C-H Alkylation of Aromatic Amides with Alkenes: Possible Generation of a Carbene Intermediate from an Alkene

“…Rhodium complexes were the candidates of choice as catalysts because there are many reactions in which the oxidative addition of C-H bonds is involved as the key step in various C-H alkylation reactions. 4,21,37 As we expected, C-H alkylation reactions with various alkenes, including acrylic esters, 30 styrenes, 38 α,β-unsaturated lactones, 39 dihydrofurans, 39 maleimides, 40 and norbornene derivatives, 41 were achieved when a rhodium catalyst was used in conjunction with an 8-aminoquinoline directing group (Scheme 3). However, the reactions did not proceed via the mechanism as we expected based on the working hypothesis, i.e., hydrometalation or carbometalation which are the generally accepted mechanisms for C-H alkylation with alkenes.…”

H-bonded reusable template assisted para-selective ketonisation using soft electrophilic vinyl ethers

“…Over the last few decades directed C−H activation has offered a promising strategy for superior regioselectivity. 17–39 However, directed carbonyl insertion is mostly explored for ortho C−H bonds. 40–44 Expanding the idea to distal para positions, spans larger separation and thus tunnels through bulky and strained intermediates, vulnerable to subtle manifold modification.…”