title: Pd(II)-catalyzed domino heterocyclization/cross-coupling of alpha-allenols and alpha-allenic esters: efficient preparation of functionalized buta-1,3-dienyl dihydrofurans.
abstract: A mild, palladium(II)-catalyzed reaction of alpha-allenols with alpha-allenic esters in a heterocyclization/cross-coupling sequence, applicable to a wide range of substitution patterns, has been developed for the preparation of 2,3,4-trifunctionalized 2,5-dihydrofurans. Our studies indicate high levels of chemo- and regiocontrol. The possibility of using optically active substrates as well as substrates of increased steric demand, such as tertiary alpha-allenols, makes this novel sequence of heterocyclization/cross-coupling an attractive method in organic synthesis. The current mechanistic hypothesis invokes a regiocontrolled palladium(II)-mediated intramolecular oxypalladation of the free allenol component, that then undergoes a cross-coupling reaction with the allenic ester partner, followed by a trans-beta-deacyloxypalladation with concomitant regeneration of the Pd(II) species.
authors.affiliation: Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense de Madrid, Spain. alcaideb@quim.ucm.es
authors.forename: Benito
authors.initials: B
authors.lastname: Alcaide
authors.forename: Pedro
authors.initials: P
authors.lastname: Almendros
authors.forename: Teresa
authors.initials: T
authors.lastname: Martínez Del Campo
authors.forename: Rocío
authors.initials: R
authors.lastname: Carrascosa