19550-45-9Relevant articles and documents
Reduction of Organic Compounds at Lead Cathodes and Mediation by Dimethylpyrrolidinium Ion
Lawin, Phillip B.,Hutson, Alan C.,Kariv-Miller, Essie
, p. 526 - 529 (1989)
Reduction of several organic compounds at Pb cathodes was studied and the use of dimethylpyrrolidinium (DMP+) as a mediator for such reactions was evaluated.Following previous reports that have shown that the reduction product of DMP+ at Pb deposits as a monolayer and bulk DMP(Pb5), the catalytic properties of both phases for organic electroreduction were investigated.Of the organic compounds investigated, the monolayer catalyzes the reduction of alkyl chlorides only.Bulk DMP(Pb5) mediates electron transfer also to several ketones, allylbenzene, and difluorobenzene.Of particular interest is the fact that the reduction of 6-hepten-2-one (5), 6-heptyn-2-one, and 5-phenylpentan-2-one can be catalyzed whereas other ketones are unaffected.Preparative electrolyses at Pb were performed with 6-chloro-1-hexene (4) and 6-hepten-2-one (5).The main product of 4 was 1-hexene, whereas 5 yielded 1,2-dimethylcyclopentanol exclusively.The reduction of 4 and 5 in the presence of catalytic amounts of DMP+ can be achieved at potentials 400 - 500 mV positive of the reduction potentials when DMP+ is absent.The mechanism of the reductive cyclization of 5 is discussed.
Reductive cyclization of enones by titanium(IV) aryloxide and a Grignard reagent
Quan, Long Guo,Cha, Jin Kun
, p. 8567 - 8569 (2007/10/03)
The titanium-mediated cyclization of δ,ε-enones by using dichlorotitanium diphenoxide-cyclohexylmagnesium chloride diastereoselectively afforded cis-substituted cyclopentanols and was thus found to parallel the stoichiometric and catalytic titanocene-mediated reactions.
Development of a method for the reductive cyclization of enones by a titanium catalyst
Kablaoui, Natasha M.,Buchwald, Stephen L.
, p. 3182 - 3191 (2007/10/03)
An effective protocol in which bis(trimethylphosphine)titanocene is used to catalyze the reductive cyclization of enones to cyclopentanols via a metallacyclic intermediate has been developed. The key step in the process is the cleavage of the titanium-oxygen bond in the metallacycle by a silane to regenerate the catalyst. Mechanistic aspects of the reaction are discussed and the diastereoselectivity of the transformation is studied using both achiral and chiral substrates. The scope and limitations of the procedure are described. An in situ protocol for the generation of the air- and moisture-sensitive catalyst has also been developed. This work demonstrates, for the first time, the viability of using an early transition metal complex to catalyze the reductive cyclization of an alkene with a heteroatom-containing functional group.An effective protocol in which bis(trimethylphosphine) titanocene is used to catalyze the reductive cyclization of enones to cyclopentanols via a metallacyclic intermediate has been developed. The key step in the process is the cleavage of the titanium-oxygen bond in the metallacycle by a silane to regenerate the catalyst. Mechanistic aspects of the reaction are discussed and the diastereoselectivity of the transformation is studied using both achiral and chiral substrates. The scope and limitations of the procedure are described. An in situ protocol for the generation of the air-and moisture-sensitive catalyst has also been developed. This work demonstrates, for the first time, the viability of using an early transition metal complex to catalyze the reductive cyclization of an alkene with a heteroatom containing functional group.
