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Doubling up: The highly regioselective C3 heteroarylation of either an indole or a pyrrole with an array of electron-rich and electron-poor N-heteroarenes has been carried out using a palladium/copper co-catalytic system. The double CH activation selectively delivers the unsymmetrical bi-heteroaryl product instead of the homocoupled products.
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Li et al. (2011) studied this question.
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