One-Pot Sequential N and C Arylations: An Efficient Methodology for the Synthesis of trans 4-N,N-Diaryl AminostilbenesWe thank the National Science Foundation for support of this work and Aldrich for research samples.

N,N-Diaryl aminostilbenes and N,N-diaryl aminostyrenes are versatile compounds that have found exciting applications in the field of photochemistry; most of these compounds are patented and they are widely used as electro-photographic photoconductors and photoreceptors. Recent reports have demonstrated, for example, that these compounds can exhibit an amino-conjugation effect in their fluorescence enhancement spectra and can act as ionophores for transition metals, and have several other applications. The synthetic routes to these compounds begin from aniline and the corresponding aryl halides through a three-step process involving an Ullmann/Vilsmeier/Wittig reaction sequence or from triphenylamine through a Vilsmeir/Wittig/palladiumcatalyzed arylation sequence. Recently, the synthesis of trans 4-N,N-diaryl aminostilbenes from the corresponding halostilbenes or aminostilbenes by palladium-catalyzed amination reactions has also been reported. Palladium-catalyzed cross-coupling reactions, facilitated by a variety of ligands, are exceedingly powerful and reliable methods for C C and C heteroatom bond formations and have a vast number of applications in the pharmaceutical, dye, agriculture, and polymer industries. In recent years, our studies of commercially available proazaphosphatranes, such as 1, which were first synthesized by us, have shown them to be efficient ligands in palladium-catalyzed N arylations and the Suzuki and Stille couplings. The substrates for these coupling reactions included aryl chlorides, which encompassed electron-poor, neutral, and electron-rich examples. Moreover, proazaphosphatranes can also function as strong non-ionic stoichiometric bases that facilitate a variety of useful organic transformations. Herein, we report a one-pot synthesis of trans 4-N,Ndiaryl aminostilbenes from commercially available starting materials using a double Buchwald–Hartwig amination/intermolecular Heck reaction sequence in the presence of [Pd2(dba)3]/1 (dba= dibenzylideneacetone) as the catalytic system. Recently, transition-metal-catalyzed sequential C C and C heteroatom bond-forming reactions have attracted synthetic chemists because of their ability to facilitate the formation of more than one bond in a one-pot reaction. Reports of palladium-catalyzed amination/intramolecular cyclization reaction sequences for the synthesis of indole derivatives illustrate the importance of such coupling reactions. A one-pot two-catalyst synthesis of 1,3-diphenylindazoles using a combination of copper-catalyzed N-arylation and palladium-catalyzed C-arylation reactions has also been reported. To the best of our knowledge, a one-pot double amination/intermolecular Heck reaction sequence has not been described to date. Herein, we present the preliminary results of such a one-pot protocol. Our studies commenced with the coupling of 4-aminostyrene with bromobenzene under the conditions given in Scheme 1. Optimization studies were carried out (Table 1),