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: In this article, the authors provide molecular insights into an NHC-catalyzed stereoselective annulation reaction between N-methylisatin and an enal leading to spirooxindole lactone in the presence of LiCl as the Lewis acid.
Abstract: An increasing number of examples are now being reported that use chiral N-heterocyclic carbenes (NHCs) in conjunction with Lewis acids to enhance catalytic potential. Herein, we provide molecular insights into an NHC-catalyzed stereoselective annulation reaction between N-methylisatin and an enal leading to spirooxindole lactone in the presence of LiCl as the Lewis acid. Mechanistic features as well as the origin of enantio- and diastereoselectivities of the catalytic reaction have been unraveled using the density functional theory (B3LYP-D3) method. The key mechanistic steps of the reaction are identified to proceed through the formation of a Breslow intermediate between the chiral NHC catalyst and the enal, an enantioselective addition of the re face of this intermediate to the re face of the carbonyl group of N-methylisatin, and an intramolecular proton transfer and lactonization that eventually provide access to (2S,3R)-spirooxindole lactone as the final product. In the most preferred pathway, the Lew...
77 citations
TL;DR: A Rh-catalyzed redox-neutral C-H functionalization of N-carbamoyl indolines with various internal alkynes has been developed, providing a divergent protocol to rapidly assemble fused-ring pyrroloquinolinone analogues by using a direct alkenylation/annulation strategy with high efficiency and selectivity.
77 citations
TL;DR: A new synthesis of 2-alkoxy-1,1-cyclobutane diesters and their first use in dipolar cycloadditions is reported, where cyclobutanes with carbon donor groups give piperidines with high trans stereoselectivity.
76 citations
TL;DR: The first chemical synthesis of solanoeclepin A, the key hatch-stimulating substance for potato cyst nematode, is reported, which has the potential to contribute to addressing one of the critical food issues of the twenty-first century.
Abstract: The first chemical synthesis of solanoeclepin A is described. The novel 5-4-6-7-5-5 polycyclic architecture was constructed in a stereoselective manner via a cyclopentene annulation strategy, the intramolecular cyclization of an epoxy nitrile intermediate, and an intramolecular Diels–Alder reaction of a furan derivative.
76 citations
TL;DR: The reaction de cyclenes-2ones avec des bromocrotonates donne en une etape les vinylcyclopropanes corespondants. Application a la synthese de l'acide retigeranique as discussed by the authors
Abstract: La reaction de cyclenes-2ones avec des bromocrotonates donne en une etape les vinylcyclopropanes corespondants. Ces derniers subissent differentes transpositions et fournissent des derives pentaleno dioxole, des bicyclo [3.3.0] octene-1, des bicyclo [4.3.0] nonene-7, des bicyclo [5.3.0] decene-8 ― carboxylates d'ethyle. Application a la synthese de l'acide retigeranique
76 citations