Photocatalytic Alkylation of Pyrroles and Indoles with α-Diazo Esters
This article describes the photoalkylation of electron-rich aromatic compounds with diazo esters. C-2-alkylated indoles and pyrroles are obtained with good yields even though the photocatalyst loading is as low as 0.075 mol %. For EWG-substituted substrates, the addition of a catalytic amount of N,N-dimethyl-4-methoxyaniline is required. Both EWG-EWG- and EWG-EDG-substituted diazo esters are suitable as alkylating agents. The reaction selectivity and mechanistic experiments suggest that carbenes/carbenoid intermediates are not involved in the reaction pathway.
Ciszewski, Lukasz W.,Durka, Jakub,Gryko, Dorota
supporting information
p. 7028 - 7032
(2019/09/12)
Transnitrilation from Dimethylmalononitrile to Aryl Grignard and Lithium Reagents: A Practical Method for Aryl Nitrile Synthesis
An electrophilic cyanation of aryl Grignard or lithium reagents, generated in situ from the corresponding aryl bromides or iodides, by a transnitrilation with dimethylmalononitrile (DMMN) was developed. DMMN is a commercially available, bench-stable solid. The transnitrilation with DMMN avoids the use of toxic reagents and transition metals and occurs under mild reaction conditions, even for extremely sterically hindered substrates. The transnitrilation of aryllithium species generated by directed ortho-lithiation enabled a net C-H cyanation. The intermediacy of a Thorpe-type imine adduct in the reaction was supported by isolation of the corresponding ketone from the quenched reaction. Computational studies supported the energetic favorability of retro-Thorpe fragmentation of the imine adduct. (Chemical Equation Presented).
Reeves, Jonathan T.,Malapit, Christian A.,Buono, Frederic G.,Sidhu, Kanwar P.,Marsini, Maurice A.,Sader, C. Avery,Fandrick, Keith R.,Busacca, Carl A.,Senanayake, Chris H.
supporting information
p. 9481 - 9488
(2015/08/11)
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