title: Tunable Metal-Catalyzed Heterocyclization Reactions of Allenic Amino Alcohols: An Experimental and Theoretical Study.
abstract: Controlled preparation of 2,5-dihydro-1H-pyrroles, 3,6-dihydro-2H-pyrans, and pyrroles has been achieved through switchable chemo- and regioselectivity in the metal-catalyzed heterocyclization reactions of allenic amino alcohols. The gold-catalyzed cycloisomerization reaction of α-amino-β-hydroxyallenes was effective as 5-endo cyclization by addition of amino functionality to the distal allene carbon to yield enantiopure 2,5-dihydro-1H-pyrroles, whereas their palladium-catalyzed cyclizative coupling reactions furnished 3,6-dihydro-2H-pyrans through a chemo- and regioselective 6-endo cycloetherification. Conversely, the gold-catalyzed heterocyclization reaction of β-amino-γ-hydroxyallenes generated exclusively pyrrole derivatives. These results could be explained through a chemo- and regioselective 5-exo aminocyclization to the central allene carbon followed by aromatization. Chemo- and regioselectivity depend on both linker elongation as well as the type of catalyst. This behavior can be justified by means of density functional theory calculations.
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: Benito
authors.initials: B
authors.lastname: Alcaide
authors.affiliation: Instituto de Química Orgánica General, IQOG-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Pedro
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: Cristina
authors.initials: C
authors.lastname: Aragoncillo
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: Gonzalo
authors.initials: G
authors.lastname: Gómez-Campillos
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: M Teresa
authors.initials: MT
authors.lastname: Quirós
authors.affiliation: Instituto de Química Orgánica General, IQOG-CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Soriano