28897-21-4Relevant 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
experimental part, p. 2774 - 2791 (2009/12/03)
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.
SYNTHESIS OF α-DAMASCONE AND 1-(2,6,6-TRIMETHYL-2-TETRAHYDROPYRANYL)-2-ALKEN-1-ONES
Erman, M. B.,Pribytkova, I. M.,Gulyi, S. E.,Bogomolova, O. A.,Cherkaev, G. V.,et al.
, p. 2294 - 2301 (2007/10/02)
α-Damascone was obtained by the reaction of α-cyclocitral with allyl bromide in the presence of zinc, followed by oxidation of the obtained alcohol with chromic acid to the ketone and isomerization of the latter with triethylamine as catalyst.The analogous synthesis of β-damascone from 1-(4,6,6-trimethyl-1,3-cyclohexadienyl)-2-buten-1-one was impossible on account of complications at the oxidation stage.The rearrangement of the acetylenic alcohols with polyvanadioorganosiloxane as catalyst led to 1-(2,6,6-trimethyl-2-tetrahydropyranyl)-2-alken-1-ones.
SELF-CONDENSATION OF ALLYLIC ALCOHOLS MEDIATED BY TiCl4
Idrissi, Mostafa El,Santelli, Maurice
, p. 1531 - 1534 (2007/10/02)
Addition of Grignard reagents to enones associated with TiCl4 leads to dehydration and Diels-Alder-like reaction giving dimeric hydrocarbons in good yields.
Alkenoyl-cyclohexadienes
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, (2008/06/13)
New cycloaliphatic unsaturated ketones and their use as perfuming and odour-modifying agents in the manufacture of perfumes and perfumed products, and as flavouring and taste-modifying agents in the preparation of foodstuffs in general and imitation flavours for foodstuffs, beverages, animal feeds, pharmaceutical preparations and tobacco products. Methods for the preparation of said cycloaliphatic unsaturated ketones.
