Topic
Annulation
About: Annulation is a research topic. Over the lifetime, 10152 publications have been published within this topic receiving 189701 citations.
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TL;DR: The method provides trans-disubstituted pyrroloindolones with good yields and excellent diastereo- and enantioselectivities and leads to tetracyclic pyrro[1,2-a]indoles with potential psychotropic and other bioactivities.
Abstract: NHC-enolate plus 3: N-heterocyclic carbenes (NHCs) serve as organocatalysts for the [2+3] annulation of nitrovinylindoles with α-chloroaldehydes via an intermediate azolium enolate. The method provides trans-disubstituted pyrroloindolones with good yields and excellent diastereo- and enantioselectivities. Further transformations lead to tetracyclic pyrrolo[1,2-a]indoles with potential psychotropic and other bioactivities.
106 citations
TL;DR: An ortho’palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.
Abstract: A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.
106 citations
TL;DR: A strategy for the synthesis of polycyclic aromatic hydrocarbons by the ring-closing olefin metathesis (RCM) of pendant olefins on a phenylene backbone has been developed and is an effective and general method for the preparation of PAHs.
Abstract: A strategy for the synthesis of polycyclic aromatic hydrocarbons (PAHs) by the ring-closing olefin metathesis (RCM) of pendant olefins on a phenylene backbone has been developed. RCM of 2,4',6',2' '-tetravinyl-[1,1';3',1' ']terphenyl and 2,2',5',2' '-tetravinyl-[1,1';4',1']terphenyl affords in high yield the isomeric [a,j] and [a,h] dibenzanthracenes, respectively. In contrast with other intramolecular annulation methods, such as Friedel-Crafts acylations, this reaction is completely regioselective. Since RCM is reversible and PAHs are often thermodynamic sinks, this strategy is an effective and general method for the preparation of PAHs. Density functional theory calculations support these results. Carbon disulfide is a suitable solvent for these reactions.
106 citations
TL;DR: Double C-H activations of C(5)-H and Csp(2)-H of 2-substituted N-vinyl- or arylimidazoles were realized without heteroatom-directing assistance by rhodium(III) catalyst, producing aza-fused heterocycles with high molecular complexity in low to excellent yields.
106 citations
TL;DR: The present green synthesis of imidazo[1,2-a]pyridine derivatives shows fascinating properties such as high regioselectivity, concise one-pot methodology, short reaction times, easy purification and avoids the use of transition metals.
106 citations