Isocyanides, which contain a moiety whose structure is isoelectronic with that of carbon monoxide, are useful C1 units in organic synthesis in addition to being excellent building blocks for nitrogen-containing heterocyclic compounds. 1 In transition-metal-catalyzed reactions, carbon monoxide inserts into carbon−metal (C−M) bonds, generating an acyl-metal species as key intermediates, and usually, monocarbonylation takes place selectively. In contrast, in the case of isocyanides, not only one molecule but two or more molecules of isocyanides can insert into C−M bonds, resulting in the formation of a mixture of mono-, di-, tri-, and oligoisocyanides- containing compounds.2−5 Thus, to develop novel synthetic reactions using isocyanides, the control of this “multiinsertion” process is necessary. In this context, we recently developed a selective reaction between isocyanides and triarylbismuth species in the presence of a Pd(OAc)2 catalyst, to selectively afford α-diimines, through the incorporation of two isocyanide molecules (Scheme 1, eq 1).6 The same reaction failed using arylating reagents of early elements such as PhB(OH)2 (eq 2). We therefore turned our focus to rate element arylating reagents and examined the reaction of t-butyl isocyanide with PhI, Ph3Sb, Ph4Sn, and Ph4Pb under similar conditions as those employed for the diarylation reaction using triarylbismuth species (eq 2). Interestingly, the use of tetraphenyllead7,8 resulted in the novel diphenylation of one isocyanide molecule to selectively give the corresponding benzophenone imine in good yield. Thus, we report our investigation into the Pd-catalyzed diarylation of isocyanides using tetraaryllead (eq 3).