Despite increasing pharmaceutical importance, fluorinated aromatic organic molecules remain difficult to synthesize. Present methods require either harsh reaction conditions or highly specialized reagents, making the preparation of complex fluoroarenes challenging. Thus, the development of new and general methods for their preparation that overcome the limitations of those techniques currently in use is of great interest. We have prepared [LPd(II)Ar(F)] complexes where L is a biaryl monophosphine ligand and Ar is an aryl group, and identified conditions under which reductive elimination occurs to form an Ar-F bond. Based on these results, we have developed a catalytic process that converts aryl bromides and aryl triflates into the corresponding fluorinated arenes using simple fluoride salts. We expect this method to allow the introduction of fluorine atoms into advanced, highly functionalized intermediates.

Palladium-catalyzed amidation of five-membered heterocyclic bromides that contain multiple heteroatoms was achieved for the first time using the Pd/1 catalyst system. This system allows for efficient access to N-arylated imidazoles, pyrazoles, thiazoles, pyrroles, and thiophenes in moderate to excellent yield. Experimental results and DFT calculations point to the need for electron-rich and especially sterically demanding biaryl phosphine ligand to promote these difficult cross-coupling reactions.

The completely N1-selective Pd-catalyzed arylation of unsymmetric imidazoles with aryl halides and triflates is described. This study showed that imidazoles have a strong inhibitory effect on the in situ formation of catalytically-active Pd(0)-ligand complex. The efficacy of the N-arylation reaction was improved drastically by the use of pre-activated solution of Pd2(dba)3 and L1. From these findings it is clear that while imidazoles can prevent binding of L1 to the Pd, once the ligand is bound to the metal, these heterocycles do not displace it. The utility of the present catalytic system was demonstrated by the regioselective synthesis of clinically important tyrosine kinase inhibitor nilotinib.

Highly N2-selective arylation of 4,5-unsubstituted and 4-substituted 1,2,3-triazoles was achieved for the first time by Pd/L1 catalyst system. A wide range of N2-aryl-1,2,3-triazoles were prepared from aryl bromides, chlorides and triflates with excellent (95–99%) N2-selectivity. DFT calculations suggest that formation of N2-arylated 1,2,3-triazoles is favored kinetically.

A series of monoligated L•PdII(Ar)X complexes (L = dialkyl biarylphosphine) have been prepared and studied in an effort to better understand an unusual dearomative rearrangement previously documented in these systems. Experimental and theoretical evidence suggest a concerted process involving the unprecedented PdII-mediated insertion of an aryl group into an unactivated arene.

A conjugated polymer containing an electron donating backbone (triphenylamine) and an electron accepting side chain (cyanoacetic acid) with conjugated thiophene units as the linkers has been synthesized. Dye‐sensitized solar cells (DSSCs) are fabricated utilizing this material as the dye sensitizer, resulting a typical power conversion efficiency of 3.39% under AM 1.5 G illumination, which represents the highest efficiency for polymer dye‐sensitized DSSCs reported so far. The results show the good promise of conjugated polymers as sensitizers for DSSC applications.magnified image

Figure 1. Homoconjugation and dihedral angle tuning. Scheme 1. Syntheses of Compounds 2−6 Communication pubs.acs.org/cm

The Pd(0)-catalyzed intermolecular C–H amination of unactivated C(sp3)–H bonds using aryl amines as the nitrogen source is disclosed. Either the C–N cross-coupling product or the C–H amination product could be accessed selectively by adjusting the steric environment of the substrate.