1152182-30-3Relevant academic research and scientific papers
Ti-catalyzed Barbier-type allylations and related reactions
Estevez, Rosa E.,Justicia, Jose,Bazdi, Btissam,Fuentes, Noelia,Paradas, Miguel,Choquesillo-Lazarte, Duane,Garcia-Ruiz, Juan M.,Robles, Rafael,Gansaeuer, Andreas,Cuerva, Juan M.,Oltra, J. Enrique
, p. 2774 - 2791 (2009)
Titanocene(III) complexes, easily generated in situ from commercial Ti IV precursors, catalyze Barbiertype allylations, intramolecular crotylations (cyclizations), and prenylations of a wide range of aldehydes and ketones. The reaction displays surprising and unprecedented mechanistic subtleties. In cyclizations a fast and irreversible addition of an allyl radical to a TiIII-coordinated carbonyl group seems to occur. Intermolecular additions to conjugated aldehydes proceed through a coupling of a Ti IV-bound ketyl radical with an allyl radical. Reactions of ketones with allylic halides take place by the classical addition of an allylic organometallic reagent. The radical coupling processes enable transformations such as the highly regioselective α-prenylation that are otherwise difficult to achieve. The mild reaction conditions and the possibility to employ titanocene complexes in only catalytic quantities are highly attractive features of our protocol. These unusual properties have been taken advantage of for the straightforward synthesis of the natural products rosiridol, shikalkin, and 12-hydroxysqualene.
