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Several highly substituted naphthalenes 3 have been synthesized in a one-pot reaction by treatment of arenes 1 with alkynes 2 in the presence of palladium acetate and silver acetate. In this Pd-catalyzed protocol, an arene provides a benzo source for the construction of a naphthalene core through twofold aryl C-H bond activation. Reaction of triphenylphosphine with diphenylethyne (2 a) under the catalysis of Pd(IV) complexes produced 1,2,3,4-tetraphenylnaphthalene (3 ba) in 62 % yield. Here, triphenylphosphine undergoes one aryl C-P bond cleavage and one aryl C-H bond activation to serve as a benzo moiety. Crystal structures of cycloadducts 3 ea, 3 ga, and 3 ac have been analyzed. The twisted naphthalenes arise not only from the overcrowded substituents but also from the contribution of the CH(3)-pi interaction.
Wu et al. (Thu,) studied this question.