Efficient Gold(I) Acyclic Diaminocarbenes for the Synthesis of Propargylamines and Indolizines

Abstract

Mononuclear gold(I) acyclic diaminocarbenes (ADCs) were prepared by the reaction of 1,2-cyclohexanediamine with the corresponding isocyanide complexes [AuCl(CNR)] (R = Cy, t Bu). The three-component coupling of aldehydes, amines, and alkynes was investigated by using these gold(I) ADC complexes. The new gold(I) metal complexes are highly efficient catalysts for the synthesis of propargylamines and indolizines in the absence of solvent and in mild conditions. This method affords the corresponding final products with excellent yields in short reaction times. Additionally, chiral gold(I) complexes with ADCs have been prepared and tried in the enantioselective synthesis of propargylamines.

An Efficient A3 Coupling Catalyst Based on a Silver Complex Bearing N‐Heterocyclic Carbene and Homoscorpionate Bis(3‐methyl‐mercaptoimidazolyl)borate Ligands

“…Despite great achievements in the past two decades in the field of A 3 coupling, these reactions still suffer from some shortcomings. For example, some of these reactions require high reaction temperatures or a high percentage of catalyst loading is required to achieve higher yields of products . Among carbene ligands, N‐heterocyclic carbenes, commonly known as NHCs, are excellent sigma donor ligands and their electronic and steric properties are adjustable by changing the nature of substituents on the nitrogen atoms .…”

“…For example, some of these reactions require high reaction temperatures or a high percentage of catalyst loading is required to achieve higher yields of products. [32] Among carbene ligands, Nheterocyclic carbenes, commonly known as NHCs, are excellent sigma donor ligands and their electronic and steric properties are adjustable by changing the nature of substituents on the nitrogen atoms. [47][48][49][50][51][52][53][54][55][56][57][58][59][60] While different salts or nanostructures of coinage metals have been utilized as catalysts for A 3 coupling reactions, reports in regards to the N-heterocyclic complexes of these metals are rare.…”

“…Multiple strategies have been implemented in the literature. Previous studies in A 3 coupling reactions have shown that coinage metals are powerful catalysts for A 3 coupling reactions . Despite great achievements in the past two decades in the field of A 3 coupling, these reactions still suffer from some shortcomings.…”

Cyclative MCRs of Azines and Azinium Salts

“…Using the same strategy, Gimeno [76] and co-workers reported a green multicomponent synthesis of aminoindolizines (74) in the presence of new gold (I) acyclic diaminocarbenes (ADCs) using aldehyde (71), acetylenes (72) and dialkylamines (73) starting materials (Scheme 14). This approach resulted in the corresponding final products with excellent yields at mild condition and short reaction time.…”

Gold Catalyzed Multicomponent Reactions beyond A3 Coupling

“…In relation with both fields of research, important contributions have been achieved with gold catalysts in the development of new multicomponent reactions, although many of these reactions have been only focused on the coupling of aldehydes, amines and alkynes known as A 3 -coupling-type reactions for the synthesis of propargylamines [ 21 , 22 ]. Since this process has already been compiled and revised in a previous pivotal review [ 23 ], we will give to the reader a broader vision of the scope of gold catalysts in the design and development of new MCRs beyond A 3 -coupling-type reactions.…”