Oxidative internal alkynes with benzoic acids

Insertion of aUcynes into aromatic C-H bonds has been achieved by iridium complexes. Shibata and coworkers found that the cationic complex [Ir(COD)2]BF4 catalyzes the hydroarylation of internal alkynes with aryl ketones in the presence of BINAP (24) [111]. The reaction selectively produces ort/to-substituted alkenated-aryl products. Styrene and norbomene were also found to undergo hydroarylation under similar condition. [Cp IrCl2]2 catalyzes aromatization of benzoic acid with two equivalents of internal alkyne to form naphthalene derivatives via decarboxylation in the presence of Ag2C03 as an oxidant (25) [112]. 

Naphthalene derivatives 158 were also prepared by the oxidative coupUng of benzoic acids 156 with internal alkynes such as diphenylacetylene 157 in the presence of [Cp lrCl2]2 complex combined with Ag2C03 as oxidant (Equation 10.42) [71]. 

Benzoic acids yield isocoumarins through a Rh-catalysed Cu-promoted oxidative coupling with internal alkynes. When a two-fold excess of alkyne is used with Ir catalysis,... 

In 2007, the Mlura group reported a Rh(III)-catalyzed oxidative coupling of benzoic acids with internal alkynes to the synthesis of isocoumarins via aromatic C-H activation (Scheme 6.24a) [38]. Importantly, the reaction of benzoic acids with alkynes takes place efficiently even with a reduced amount (5mol%) of Cu(0Ac)2-H20 under air (Scheme 6.24b) [5b]. The same group also developed the rhodium-catalyzed coupling of acrylic acids with alkynes to provide corresponding a-pyrone via vinylic C-H bond cleavage (Scheme 6.24c) [5c]. In 2015, Wen and coworkers described a Rh(III)-catalyzed synthesis of... 

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