title: Water freezing as a regiocontrol element in the multicomponent assembly of cyclic enones.
abstract: Regioselective synthesis of dialkoxy 2-cyclopentenones and 2-cyclohexenones with novel substitution patterns has been accomplished by the one-pot combination of three simple starting materials (chromium carbene complex, Weinreb acetamide lithium enolate and 1-alkoxyallenyllithium) under either anhydrous conditions or water-promoted solidification of the reaction mixture. These results revealed an unprecedented water-freezing effect that plays a key role to completely reverse the regioselectivity of the intramolecular carbometalation of an allene moiety.
authors.affiliation: Departamento de Química Orgánica e Inorgánica and Instituto Universitario de Química Organometálica "Enrique Moles", Universidad de Oviedo, Julián Clavería 8, 33006 Oviedo, Asturias (Spain), Fax: (+34) 985-103446.
authors.forename: Raquel
authors.initials: R
authors.lastname: De la Campa
authors.forename: Josefa
authors.initials: J
authors.lastname: Flórez
keywords: carbene ligands; cyclization; enones; multicomponent reactions; water freezing