title: Metal-Catalyzed Cyclization Reactions of 2,3,4-Trien-1-ols: A Joint Experimental-Computational Study.
abstract: Controlled preparation of tri- and tetrasubstituted furans, as well as carbazoles has been achieved through chemo- and regioselective metal-catalyzed cyclization reactions of cumulenic alcohols. The gold- and palladium-catalyzed cycloisomerization reactions of cumulenols, including indole-tethered 2,3,4-trien-1-ols, to trisubstituted furans was effective, due to a 5-endo-dig oxycyclization by attack of the hydroxy group onto the central cumulene double bond. In contrast, palladium-catalyzed heterocyclization/coupling reactions with 3-bromoprop-1-enes furnished tetrasubstituted furans. Also studied was the palladium-catalyzed cyclization/coupling sequence involving protected indole-tethered 2,3,4-trien-1-ols and 3-bromoprop-1-enes that exclusively generated trisubstituted carbazole derivatives. These results could be explained through a selective 6-endo-dig cumulenic hydroarylation, followed by aromatization. DFT calculations were carried out to understand this difference in reactivity.
authors.affiliation: Grupo de Lactamas y Heterociclos Bioactivos, Departamento de Química Orgánica I, Unidad Asociada al CSIC, Facultad de Química, Universidad Complutense de Madrid, 28040, Madrid, Spain. alcaideb@quim.ucm.es.
authors.forename: Benito
authors.identifier: http://orcid.org/0000-0002-2180-9605
authors.initials: B
authors.lastname: Alcaide
authors.affiliation: Instituto de Qímica General, Consejo Superior de Investigaciones Científicas, IQOG-CSIC, Juan de la Cierva 3, 28006, Madrid, Spain. Palmendros@iqog.csic.es.
authors.forename: Pedro
authors.identifier: http://orcid.org/0000-0001-6564-2758
authors.initials: P
authors.lastname: Almendros
authors.affiliation: Grupo de Lactamas y Heterociclos Bioactivos, Departamento de Química Orgánica I, Unidad Asociada al CSIC, Facultad de Química, Universidad Complutense de Madrid, 28040, Madrid, Spain.
authors.forename: Sara
authors.identifier: http://orcid.org/0000-0001-9884-9042
authors.initials: S
authors.lastname: Cembellín
authors.affiliation: Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense de Madrid, 28040, Madrid, Spain. israel@quim.ucm.es.
authors.forename: Israel
authors.identifier: http://orcid.org/0000-0002-0186-9774
authors.initials: I
authors.lastname: Fernández
authors.affiliation: Grupo de Lactamas y Heterociclos Bioactivos, Departamento de Química Orgánica I, Unidad Asociada al CSIC, Facultad de Química, Universidad Complutense de Madrid, 28040, Madrid, Spain.
authors.forename: Teresa
authors.identifier: http://orcid.org/0000-0002-8729-4085
authors.initials: T
authors.lastname: Martínez Del Campo
keywords: cumulenes; cyclization; density functional calculations; gold; palladium