Isocyanides, which contain a moiety whose structure isisoelectronic with that of carbon monoxide, are useful C1units in organic synthesis in addition to being excellentbuilding blocks for nitrogen-containing heterocyclic compounds.1 In transition-metal-catalyzed reactions, carbonmonoxide inserts into carbon−metal (C−M) bonds, generatingan acyl-metal species as key intermediates, and usually,monocarbonylation takes place selectively. In contrast, in thecase of isocyanides, not only one molecule but two or moremolecules of isocyanides can insert into C−M bonds, resultingin the formation of a mixture of mono-, di-, tri-, and oligoisocyanides-containing compounds.2−5 Thus, to develop novelsynthetic reactions using isocyanides, the control of this“multiinsertion” process is necessary. In this context, werecently developed a selective reaction between isocyanidesand triarylbismuth species in the presence of a Pd(OAc)2catalyst, to selectively afford α-diimines, through theincorporation of two isocyanide molecules (Scheme 1, eq1).6 The same reaction failed using arylating reagents of earlyelements such as PhB(OH)2 (eq 2). We therefore turned ourfocus to rate element arylating reagents and examined thereaction of t-butyl isocyanide with PhI, Ph3Sb, Ph4Sn, andPh4Pb under similar conditions as those employed for thediarylation reaction using triarylbismuth species (eq 2).Interestingly, the use of tetraphenyllead7,8 resulted in thenovel diphenylation of one isocyanide molecule to selectivelygive the corresponding benzophenone imine in good yield.