CuBr/NHPI co-catalyzed aerobic oxidative [3 + 2] cycloaddition-aromatization to access 5,6-dihydro-pyrrolo[2,1-a]isoquinolines

Abstract

An efficientl and enviromental friendly CuBr /NHPI co-catalyzed aerobic oxidative [3+2] cycloaddition-aromatization cascade was realized with N-substituted tetrahydroisoquinolines and electron-deficient olefins. Under the mild conditions, the reaction proceeded smoothly and...

Aerobic Oxidative EDA Catalysis: Synthesis of Tetrahydroquinolines Using an Organocatalytic EDA Active Acceptor

“…As a starting point for the study, N-substituted maleimides were chosen as reaction partners due to their well-known reactivity with aromatic α-amino alkyl radicals, forming tetrahydroquinolines under a range of reaction conditions. ,− The photochemically driven annulation reaction between DMA 1a and N -phenyl maleimide ( 2a ) to furnish tetrahydroquinoline ( 3a ) proceeded smoothly without an external photocatalyst under UV irradiation . However, the initial screening of reaction conditions, presented in Table , shows that visible light irradiation (with a white compact fluorescent lamp) in the absence of a catalyst resulted in a low yield.…”

Recent progress in the synthesis of pyrrolo[2,1-a]isoquinolines

“…The CuBr/NHPI co-catalyzed construction of 5,6-dihydropyrrolo[2,1- a ]isoquinoline derivatives via an aerobic oxidative 1,3-dipolar cycloaddition/aromatization cascade has been reported by Li, Xie and coworkers (Scheme 5). 10 This process features a broad substrate scope of dipolarophiles such as N -substituted maleimides, unsaturated carbonyl compounds, acrylonitrile and nitroolefins. In general, moderate to good yields can be obtained.…”

Photocatalytic Oxidative [3+2] Cycloaddition for Pyrrolo[2,1‐a]isoquinoline Synthesis Using a Porphyrin‐Based Covalent Organic Framework

“…Therefore, great efforts have been devoted to the development of methodologies for the construction of pyrrolo[2,1‐ a ]isoquinolines, including electrocyclization pathway, double‐barreled Heck cyclization, and so on [6–15] . Among them, the dipolar [3+2] cycloadditions between azomethine ylides and dipolarophiles have attracted special attention, because it allows the construction of pyrrolo[2,1‐ a ]isoquinolines in a straightforward and convenient way [16–26] . In this strategy, a variety of metal complexes based on Cu (II), Co(II), Rh(II), or molecular KI, I 2 , N ‐heterocyclic carbene were employed as the catalysts in conjunction with suitable oxidants.…”