title: Direct Metal-Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications.
abstract: The [2+2] cycloaddition of ynamides with the highly polarized reagent Tf2 C=CH2 has been developed to regioselectively afford bis(triflyl)aminocyclobutenes in the absence of catalyst under mild conditions. Incidentally, with the ynamides bearing electron-rich aromatic rings at the C-terminal, an interesting reactivity switch was observed; a cyclization/hydroxylation sequence yielded 2-amino-3-(triflyl)cyclobut-2-enols. Aminocyclobutene construction with addition of alcohols resulted in the formation of aminocyclobutenyl ethers through a cyclization/hydroalkoxylation process. Moreover, the utility of functionalized aminocyclobutenes as precursors for further elaboration was demonstrated with the preparation of α-amino-β,γ-unsaturated ketones and 3-(triflyl)buta-1,3-dien-2-amines through 4 π-electrocyclic ring opening.
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 Química Orgánica 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: Carlos
authors.identifier: http://orcid.org/0000-0003-3698-1405
authors.initials: C
authors.lastname: Lázaro-Milla
keywords: alkynes; amides; cyclization; fluorine; small ring systems