Efficient Heterogeneous Gold(I)‐Catalyzed Direct C(sp²)–C(sp) Bond Functionalization of Arylalkynes through a Nitrogenation Process to Amides

Abstract

The first heterogeneous gold(I)‐catalyzed direct C(sp2)–C(sp) bond functionalization of arylalkynes through a nitrogenation process to amides has been achieved by using an ordered mesoporous silica (MCM‐41)‐immobilized phosphine gold(I) complex [MCM‐41‐PPh3‐AuCl] as catalyst and silver carbonate (Ag2CO3) as cocatalyst with trimethylsilyl azide (TMSN3) as a nitrogen source, yielding a variety of amides in moderate to excellent yields under mild conditions. This heterogeneous phosphine gold(I) complex shows the same turnover numbers as the homogeneous chloro(triphenylphosphine)gold(I) (Ph3PAuCl) and can easily be recovered by simple filtration of the reaction solution and recycled at least eight times without significant loss of activity, providing a novel, efficient, practical and economic method for the synthesis of amides from alkynes.magnified image

Heterogeneous Gold(I)‐Catalyzed Oxidative Ring Expansion of 2‐Alkynyl‐1,2‐Dihydropyridines or ‐Quinolines Towards Functionalized Azepines or Benzazepines

“…Three diphenylphosphine‐functionalized MCM‐41‐immobilized gold(I) complexes [MCM‐41‐Ph 2 P−AuX, X=OTf, NTf 2 , and SbF 6 ] were easily prepared according to the procedure illustrated in Scheme . The condensation of mesoporous MCM‐41 with commercially available 2‐(diphenylphosphino)ethyl‐triethoxysilane in toluene at 100 °C for 24 h, followed by silylation with Me 3 SiCl in toluene at room temperature for 24 h gave diphenylphosphine‐functionalized MCM‐41 material (MCM‐41‐Ph 2 P). The latter was reacted with Me 2 SAuCl in dichloromethane (DCM) at room temperature for 8 h to give MCM‐41‐Ph 2 P−AuCl [ A ] .…”

“…All chemicals were purchased from commercial suppliers and were used without purification before use. Mesoporous MCM‐41, 2‐alkynyl‐1,2‐dihydropyridine and its analogues 1 a – 1 w and 3 a – 3 e were prepared according to literature procedures. Toluene was dried over sodium and distilled before use.…”

“…Mesoporous silica material MCM‐41 has emerged as a smart and powerful support for immobilization of homogeneous metal catalysts due to its advantageous properties over other solid supports such as high surface area, big pore volume, homogeneity of the pores, and high thermal stability . Recently, MCM‐41‐supported gold(I) or gold(III) complexes have been successfully applied in many carbon‐carbon and carbon‐heteroatom bond‐forming reactions as highly efficient and recyclable catalysts ––. In continuation of our interest in development of highly efficient heterogeneous gold catalytic systems for organic transformations,– herein we report the synthesis of an MCM‐41‐immobilized diphenylphosphine gold(I) complex [MCM‐41‐Ph 2 P−AuNTf 2 ] and its successful application to oxidative ring expansion of 2‐alkynyl‐1,2‐dihydropyridines or ‐quinolines leading to functionalized azepine derivatives in mostly high to excellent yields under mild conditions (Scheme ).…”

“…Recently, MCM‐41‐supported gold(I) or gold(III) complexes have been successfully applied in many carbon‐carbon and carbon‐heteroatom bond‐forming reactions as highly efficient and recyclable catalysts ––. In continuation of our interest in development of highly efficient heterogeneous gold catalytic systems for organic transformations,– herein we report the synthesis of an MCM‐41‐immobilized diphenylphosphine gold(I) complex [MCM‐41‐Ph 2 P−AuNTf 2 ] and its successful application to oxidative ring expansion of 2‐alkynyl‐1,2‐dihydropyridines or ‐quinolines leading to functionalized azepine derivatives in mostly high to excellent yields under mild conditions (Scheme ). The new heterogeneous gold(I) catalyst can easily be recovered by a simple filtration of the reaction solution and recycled up to eight times with almost consistent activity.…”

Recent Advances in the Functionalization of Hydrocarbons: Synthesis of Amides and its Derivatives

“…Recently, Nie et al. investigated the synthesis of heterogeneous MCM‐41‐immobilized phosphine gold(I) complex (MCM‐41‐PPh 3 ‐AuCl) from readily available starting materials (Scheme a) . They successfully applied this catalyst to the synthesis of amides via direct C(sp 2 )−C(sp) bond functionalization of arylalkynes with trimethylsilyl azide (TMSN 3 ) as a nitrogen source.…”