Publicaciones > Sanjuán et al

Org Lett. 2016 Mar 4;18(5):1072-5. doi: 10.1021/acs.orglett.6b00191.

Formal [4+1] Cycloadditions of β,β-Diaryl-Substituted ortho-(Alkynyl)styrenes through Gold(I)-Catalyzed Cycloisomerization Reactions.

Ana M Sanjuán, Cintia Virumbrales, Patricia García-García, Manuel A Fernández-Rodríguez, Roberto Sanz

Área de Química Orgánica, Departamento de Química, Facultad de Ciencias, Universidad de Burgos , Pza. Misael Bañuelos s/n, 09001-Burgos, Spain.

Abstract

Gold(I)-catalyzed cycloisomerization of β,β-diaryl-o-(alkynyl)styrenes at 80 °C selectively yields dihydroindeno[2,1-a]indenes in a transformation that encompasses a formal [4+1] cycloaddition and takes place through a cascade 5-endo-cyclization-diene activation-iso-Nazarov cyclization. In addition, by performing the reaction at 0 °C, the same substrates exclusively give rise to benzofulvene derivatives, which have also been shown to be intermediates in the formation of the tetracyclics.

Publicaciones > Otero et al

Tetrahedron Lett. 2015; 56(1):195-198. doi: 10.1016/j.tetlet.2014.11.071

Gold-catalyzed synthesis of oxepinones: an experimental mechanistic evidence

Eva M. Otero, Jesús M. Fernández-García, Manuel A. Fernández-Rodríguez, Enrique Aguilar

Palabras clave: Gold catalysis; Oxepinones; Mechanism; π-Acids; Vinylcyclopropenes

Resumen

The isolation of a bicyclic lactone and its room temperature isomerization in CDCl3 to the expected oxepinone allows confirmation of a previously proposed mechanism for the gold-catalyzed synthesis of oxepinones from donor–acceptor alkynylcyclopropanes. However, the unsuccessful conversion of another bicyclic lactone into its corresponding oxepinone points out to a substrate-dependent mechanism.

Publicaciones > Sanjuán et al

Chemistry. 2015 Feb 9;21(7):3042-52. doi: 10.1002/chem.201405789. Epub 2014 Dec 29. PubMed 25557166

Gold(I)-catalyzed cycloisomerizations and alkoxycyclizations of ortho-(alkynyl)styrenes.

Ana M Sanjuán, Muhammad A Rashid, Patricia García-García, Alberto Martínez-Cuezva, Manuel A Fernández-Rodríguez, Félix Rodríguez, Roberto Sanz

Área de Química Orgánica, Departamento de Química, Facultad de Ciencias, Universidad de Burgos, Pza. Misael Bañuelos s/n, 09001 Burgos (Spain) http://www2.ubu.es/ginves/cien_biotec/sintorg/uk/index.htm.

Keywords: asymmetric catalysis; cyclization; cycloisomerization; gold; indenes

Abstract

Indenes and related polycyclic structures have been efficiently synthesized by gold(I)-catalyzed cycloisomerizations of appropriate ortho-(alkynyl)styrenes. Disubstitution at the terminal position of the olefin was demonstrated to be essential to obtain products originating from a formal 5-endo-dig cyclization. Interestingly, a complete switch in the selectivity of the cyclization of o-(alkynyl)-α-methylstyrenes from 6-endo to 5-endo was observed by adding an alcohol to the reaction media. This allowed the synthesis of interesting indenes bearing an all-carbon quaternary center at C1. Moreover, dihydrobenzo[a]fluorenes can be obtained from substrates bearing a secondary alkyl group at the β-position of the styrene moiety by a tandem cycloisomerization/1,2-hydride migration process. In addition, diverse polycyclic compounds were obtained by an intramolecular gold-catalyzed alkoxycyclization of o-(alkynyl)styrenes bearing a nucleophile in their structure. Finally, the use of a chiral gold complex allowed access to elusive chiral 1H-indenes in good enantioselectivities.