Palladium-catalyzed selective N-(hetero)arylation or N,N′-di(hetero)arylation of 1-aminoindoles

Palladium‐Catalyzed Cross‐Coupling of 1‐Aminoazoles with Aryl Chlorides: Application to the Synthesis of Unsymmetrical N,N′‐Diaryl‐1‐aminoindoles

“…Each of these goals was met with success by using the Pd 2 (dba) 3 /Xphos combination. Herein we wish to disclose our full results that extend the scope of our earlier communication 17…”

“…To establish the appropriate conditions for the monoarylation reaction, 1‐aminoindole 1a and 4‐chloroanisole 2a were selected as model substrates. The coupling was investigated under our previously reported conditions,17 using t‐ BuOK (2 equiv.) as the base, LiCl (2 equiv.)…”

“…In our preliminary study,17 difficulties associated with challenging 1‐aminoindoles have been addressed by the use of Josiphos ligand in combination with Pd 2 (dba) 3 in the presence of t‐ BuOK as the base and LiCl as the additive. Under these conditions, 1‐aminoindoles 1 were selectively coupled with the more reactive organic halides, aryl iodides and bromides to provide a variety of N ‐(hetero)aryl‐1‐aminoindoles 3 .…”

Palladium‐Catalyzed Coupling of N‐Amino­azoles with 3‐Halo‐Substituted ­Quinolin‐2(1H)‐ones, Coumarins, Quin­oxalin‐2(1H)‐ones, and Chromenes

“…However, this transformation was inefficient and resulted in a poor 19 % yield of 3a . Next, we examined the coupling reaction by using our reported catalytic system [Pd 2 dba 3 (dba = dibenzylideneacetone)/Josiphos], which was used in the N ‐arylation of 1‐aminoindoles with aryl iodides and bromides as coupling partners 14. We were delighted to find that this catalytic system efficiently led to compound 3a in 63 % yield (Scheme , Conditions 2).…”

Photo-Induced N–N Coupling of o-Nitrobenzyl Alcohols and Indolines To Give N-Aryl-1-amino Indoles

“…Three pioneering groups have tried two methods to construct N -aryl-1-amino indoles (Scheme ). The first protocol is starting from indole, which can generate 1-amino indole with hydroxylamine- O -sulfonic acid and strong bases, and followed by a Pd-catalyzed C–N cross-coupling reaction with relative halide (Scheme a) . Tunge et al .…”