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 first synthesis of polysubstituted quinoline derivatives from aromatic or aliphatic alcohols with RuCl2(dmso)4 as catalyst under solvent-free conditions is described in this paper.
97 citations
TL;DR: A highly efficient and mild palladium-catalyzed, one-pot, four-step cascade annulation has been developed to afford functionalized β- and γ-lactones in moderate to good yields with high regio- and diastereoselectivities in ionic liquids.
Abstract: A highly efficient and mild palladium-catalyzed, one-pot, four-step cascade annulation has been developed to afford functionalized β- and γ-lactones in moderate to good yields with high regio- and diastereoselectivities in ionic liquids The employment of ionic liquids under mild reaction conditions makes this transformation green and practical Especially, this reaction provided a novel and convenient methodology for the construction of naturally occurring biologically active β- and γ-lactones
96 citations
TL;DR: The disclosed procedures broaden significantly the synthetic applicability of the oxidative intramolecular diamination of alkenes with tethered ureas and related groups as the nitrogen source.
Abstract: The oxidative intramolecular diamination of alkenes with tethered ureas and related groups as the nitrogen source has been investigated both with the iodonium reagent IPy(2)BF(4) (Py=pyridine) and under palladium catalysis in the presence of copper(II) bromide as a reoxidant. For terminal alkenes, the two procedures enable selective and high-yielding transformations. Studies with deuterated material led to the conclusion that the reactions proceed through different stereochemical pathways. An advanced protocol for palladium-catalyzed diamination through six-membered-ring annulation was also developed, and the first examples of the intramolecular diamination of internal alkenes are described. In this case, the same stereochemical outcome was observed for the iodonium-promoted and palladium-catalyzed transformations. On this basis, it was possible to determine the importance of aminohalogenated intermediates in both diamination reactions. Overall, the disclosed procedures broaden significantly the synthetic applicability of the oxidative intramolecular diamination of alkenes.
96 citations
TL;DR: A nickel-catalyzed C-H functionalization of 2-pyridones and subsequent cyclization affords 1,6-annulated 2- pyridone motif by selective intramolecular olefin hydroarylation, which was further applied in the synthesis of the lupin alkaloid cytisine.
Abstract: The 1,6-annulated 2-pyridone motif is found in many biologically active compounds and its close relation to the indolizidine and quinolizidine alkaloid core makes it an attractive building block. A nickel-catalyzed CH functionalization of 2-pyridones and subsequent cyclization affords 1,6-annulated 2-pyridones by selective intramolecular olefin hydroarylation. The switch between the exo- and endo-cyclization modes is controlled by two complementary sets of ligands. Irrespective of the ring size, the regioselectivity during the cyclization is under full catalyst control. Simple cyclooctadiene promotes an exo-selective cyclization, whereas a bulky N-heterocyclic carbene ligand results in an endo-selective mode. The method was further applied in the synthesis of the lupin alkaloid cytisine.
96 citations
96 citations