Assembly of tetracyclic tetrahydrocarbazoles via a visible-light promoted cascade process

Abstract

We disclose an efficient method for the synthesis of tetracyclic tetrahydrocarbazoles via a visible-light promoted cascade reaction of alkene tethered indoles and bromodifluoroacetate esters. This reaction involves two C–C bonds...

The Synthesis of 5,6‐dihydrobenzo[4,5]imidazo[2,1‐a]isoquinoline Derivatives via Metal‐Free Radical Cascade Pathway

“…In summary, we have developed an oxidative radical cyclization of methyl 2-((2-phenyl-1Hbenzo[d]imidazol-1-yl)methyl)acrylates with a wide variety of hydrocarbons, including ethers, toluenes, alcohols and cycloalkanes, via direct C(sp 3 )-H functionalization following addition/cyclization cascade. This reaction gives 5,6-dihydrobenzo [4,5]imidazo [2,1a]isoquinoline derivatives, specially spiro compounds. Further studies on the application of these compounds in drug discovery are currently ongoing in our laboratory.…”

“…The fused-benzimidazole derivatives are ubiquitous structural motifs, which could be found in majority of natural and pharmaceutically interesting compounds. [1] Specially, 5,6-dihydrobenzo [4,5]imidazo [2,1a]isoquinoline skeleton, a subclass of benzimidazole family, is known as the core structure of many pharmaceutically active compounds and functional materials (Figure 1), [2] and has attracted increasing attention from both synthetic and medicinal chemists. Because of the significance of this skeleton, huge efforts have been devoted into the assembly of this special type of heterocyclic moiety.…”

“…[3] Indeed, all of papers for the preparation of 5,6dihydrobenzo [4,5]imidazo [2,1-a]isoquinolines are focused on the benzo[d]imidazol-1-yl)prop-2-en-1-ones bearing a carbonyl group in C-6 position (Scheme 1b). [4] Nevertheless, to the best of our knowledge, there are no related reports about the derivatization of 5,6-dihydrobenzo [4,5]imidazo [2,1-a]isoquinolines which contain 2H in C-6 position.…”

“…To extend the application of this unique skeleton in organic and medicinal chemistry, it is meaningful to develop a high-efficiency approach to synthesize the derivatives. In continuation of our research on the functionalization of activated alkenes, we report a mild and metal-free radical cascade reaction of 2-aryl-Nacrylate with different substrates to construct various [4,5]imidazo [2,1-a]isoquinolines. 5,6-dihydrobenzo[4,5]imidazo[2,1-a]isoquinoline derivatives (Scheme 1c).…”

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

“…Owing to their remarkable significance, developing convenient synthetic protocols for functionalized tetrahydrocarbazoles has attracted continual attention in synthetic and pharmaceutical chemistry [8][9][10][11][12][13][14][15]. Among many well-designed strategies for the synthesis of tetrahydrocarbazoles, the direct assembly of the tetrahydrocyclohexenyl ring with readily available functionalized indoles as pre-cursors has proven to be one of the most efficient synthetic protocols [16][17][18][19][20][21]. Therefore, many [4 + 2] reactions of 3-vinylindolines or 2-vinylindolines with diverse dienophiles have been successfully developed for the synthesis of many tetrahydrocarbazole and carbazole derivatives .…”