2019
DOI: 10.1002/adsc.201900512
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Heterogeneous Gold(I)‐Catalyzed Oxidative Ring Expansion of 2‐Alkynyl‐1,2‐Dihydropyridines or ‐Quinolines Towards Functionalized Azepines or Benzazepines

Abstract: A novel and efficient heterogeneous gold(I)-catalyzed highly regio-and chemoselective oxidative ring expansion of 2-alkynyl-1,2-dihydropyridines or -quinolines has been developed that proceeds smoothly through exclusive 1,2-migration of a vinyl or phenyl group with pyridine N-oxide as oxidant under mild conditions. The reaction provides a general and practical method for the synthesis of a wide variety of azepine derivatives with high atom-economy, high to excellent yield, broad functional group tolerance, and… Show more

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Cited by 26 publications
(8 citation statements)
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“…Furthermore, the Cai group achieved the oxidative ring expansion of 2‐alkynyl‐1,2‐dihydropyridines or quinolines using MCM‐41‐immobilized diphenylphosphine gold(I) complex [MCM‐41‐Ph 2 P−AuNTf 2 ] as a catalyst. The heterogeneous gold catalyst efficiently produced the desired azepines in high yield and can be recovered and recycled up to eight times without losing its efficiency (Scheme 8c) [56] …”
Section: Skeletal Editing Of Heteroarenesmentioning
confidence: 99%
See 1 more Smart Citation
“…Furthermore, the Cai group achieved the oxidative ring expansion of 2‐alkynyl‐1,2‐dihydropyridines or quinolines using MCM‐41‐immobilized diphenylphosphine gold(I) complex [MCM‐41‐Ph 2 P−AuNTf 2 ] as a catalyst. The heterogeneous gold catalyst efficiently produced the desired azepines in high yield and can be recovered and recycled up to eight times without losing its efficiency (Scheme 8c) [56] …”
Section: Skeletal Editing Of Heteroarenesmentioning
confidence: 99%
“…The heterogeneous gold catalyst efficiently produced the desired azepines in high yield and can be recovered and recycled up to eight times without losing its efficiency (Scheme 8c). [56] Recently, the Beeler group has developed a photocatalyzed dearomative rearrangement of pyridinium ylide generated from the photolysis of ethyl diazoacetate with excess pyridine, affording azepines in low-yield. However, the formation of competitive carbene coupling byproducts, such as diazine and 2,3-diphenylmaleate, has limited the practical applicability.…”
Section: Ring Expansion Reactions Of Pyridinium Ylidesmentioning
confidence: 99%
“…14 In recent years, diverse functionalized MCM-41-immobilized gold( i ) or gold( iii ) complexes have successfully been applied to various important organic reactions. 15 As gold redox chemistry includes oxidation, the potential oxidation of solid-supported phosphine ligand has been a major concern that hinders the development of recyclable gold catalysts for gold redox catalysis since the oxidation of the heterogenized phosphine ligand might cause the rapid gold catalyst decomposition. Thus, the development of an efficient and recyclable gold catalyst for gold redox catalysis is highly desirable.…”
Section: Introductionmentioning
confidence: 99%
“…The nano-sized mesoporous silica material MCM-41 has been broadly employed as an ideal and promising support for anchoring homogeneous catalysts because of its specific properties including a high surface area, a big pore volume, homogeneity of the pores, and high thermal stability compared with other insoluble supports . To date, diverse gold­(I) or gold­(III) complexes grafted onto MCM-41 have been successfully applied to some important organic transformations as recyclable gold catalysts . Recently, we disclosed the synthesis of an MCM-41-anchored diphenylphosphine gold­(I) catalyst [MCM-41-Ph 2 P-AuNTf 2 ] and its catalytic behavior in ring expansion reaction of 2-alkynyl-1,2-dihydropyridines or -quinolines, leading to functionalized azepines or benzazepines .…”
Section: Introductionmentioning
confidence: 99%