Electrochemically driven, Cp*Ir(III)-catalyzed regioselective annulative couplings of benzoicacids with alkynes have been established herein. The combination of iridium catalyst and electricity not only circumvents the need for stoichiometric amount of chemical oxidant, but also ensures broad reaction compatibility with a wide array of sterically and electronically diverse substrates. This electrochemical
Cp*Ir<sup>III</sup>-Catalyzed Oxidative Coupling of Benzoic Acids with Alkynes
作者:Daniel A. Frasco、Cassandra P. Lilly、Paul D. Boyle、Elon A. Ison
DOI:10.1021/cs400656q
日期:2013.10.4
Cp*Ir(III) complexes have been shown to catalyze the oxidative coupling of benzoic acids with alkynes in methanol at 60 °C to form a variety of isocoumarins. The use of AgOAc as an oxidant was required to facilitate significant product formation. Alkyl alkynes were shown to be more reactive substrates than aryl alkynes, and a number of functional groups were tolerated on benzoic acid. Combined mechanistic
An inexpensive cationic ruthenium(II) catalyst enabled the expedient synthesis of isocoumarins through oxidative annulations of alkynes by benzoic acids. This C-H/O-H bond functionalization process also proved applicable to the preparation of alpha-pyrones and was shown to proceed by rate-limiting C-H bond ruthenation.