New Cyclization Partners

To close on the new cyclization partners used in cobalt-catalyzed [2 + 2 + 2] cycloaddition to give benzene derivatives, it is worth mentioning that alkynyl halides have been used for the first time in this transformation [29]. Until then, only ruthenium-based catalysts had been used with such substrates [30]. While the standard catalysts CpCo(CO)2 and CpCo(C2H4)2 did not allow the formation of cycloadducts, the new catalyst III proved able to accomplish this task efficiently starting from alkynyl bromides 59 and 62 (Scheme 1.15). 

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