Palladium-catalysed amination of 2-acyl-1-alkyl-5-bromopyrroles

Abstract

Abstract-The first intermolecular C-N bond-forming reactions between substituted 2-bromopyrroles and primary and cyclic secondary amines were performed using Pd 2 (dba) 3 as catalyst with BINAP as the ligand. The aminations proceeded in the presence of NaO t Bu at 80-100°C in 31-93% yields.

Synthesis and properties of novel second-order NLO chromophores containing pyrrole as an auxiliary electron donor

“…Pd-catalyzed direct amination of aromatic rings such as halobenzenes and halothiophenes is an efficient method for C-N formation. 26 However, such a method was not successful with halopyrrole until 2004 when Alvarez-Builla and co-workers 27 reported the first Pd-catalyzed cross coupling reaction between 2-acetyl substituted 5-bromo-N-methylpyrrole and amines.…”

“…28 The synthesis of aminated pyrrole compounds 5, 6 and 7 was accomplished via a modified method reported by Alvarez-Builla and co-workers. 27 As shown in Scheme 1, 4 reacts with piperidine in toluene in the presence of Pd 2 (dba) 3 as a catalyst and BINAP as a ligand to give 5 in a very high yield of 96%. In contrast to the reaction conditions reported by Alvarez-Builla and co-workers, we found it was necessary to use a relatively weak base of caesium carbonate, a higher reaction temperature of 110 C and a higher catalyst-to-ligand ratio of 1/1.5 to ensure the high reaction yield.…”

Highly Reactive, General and Long-Lived Catalysts for Palladium-Catalyzed Amination of Heteroaryl and Aryl Chlorides, Bromides, and Iodides: Scope and Structure–Activity Relationships

“…32,[68][69][70][71] The strong NaOtBu base, more than the palladium catalyst, limits the tolerance of the process to ancillary functionality. Several approaches have been followed to address functional group compatability.…”

Palladium‐Catalysed Cross‐Coupling and Related Reactions Involving Pyrroles

“…Type I Pd 0 ‐catalysed C–N bond‐forming reactions between C ‐halogenated pyrroles and amines, and so leading to C ‐aminated pyrroles, have only been reported recently 31,32. The conversion 17 + 18 → 19 shown in Scheme is indicative and highlights the great potential of this sort of process.…”