39546-75-3Relevant academic research and scientific papers
Electrochemical Reduction of Ketones Mediated by (Dimethylpyrrolidinio)mercury. Reductive Cyclization of Unsaturated Ketones and Redox Catalysis Studies
Swartz, James E.,Mahachi, Tendai J.,Kariv-Miller, Essie
, p. 3622 - 3628 (1988)
The mechanism of dimethylpyrrolidinium (DMP(+1)) mediation of the reductive cyclization of 6-hepten-2-one at a mercury electrode was studied.The initial step of the reduction involves formation of a solid composite, (DMP)Hg5, which then transfers an electron to the ketone, regenerating DMP(1+) and Hgo.The ketyl radical anion cyclizes to form a primary alkyl radical, which can either abstract a hydrogen atom from the solvent, dimethylformamide, or be reduced to the corresponding carbanion.Protonation gives 1,2-dimethylcyclopentanol.Both direct and DMP(1+)-mediated reductions of 7-octen-2-one, 5-phenyl-2-pentanone, and 6-heptyn-2-one were studied.All three compounds give cyclic alcohols when the reduction is mediated by DMP(1+).The former two compounds give the corresponding straight-chain alcohols when reduced directly.The latter gives the same cyclized product upon both direct or DMP(1+)-mediated reduction.Redox catalysis studies show that DMP(1+) is a remarkably effective catalysts for the reduction of ketones.The effectiveness of the catalysis correlates with the expected rates of cyclization of the unsaturated ketones and is consistent with a mechanism involving mediation by solid (DMP)Hg5.Redox catalysis studies of the reduction of cyclohexanones indicate that DMP(1+)-mediated reductions are accelerated by increasing , and the results are discussed in terms of a mechanism leading to pinacol formation.
Samarium(II) Iodide-Induced Reductive Cyclization of Unactivated Olefinic Ketones. Sequential Radical Cyclization/Intermolecular Nucleophilic Addition and Substitution Reactions
Molander, Gary A.,McKie, Jeffrey A.
, p. 3132 - 3139 (2007/10/02)
Samarium(II) iodide in the presence of HMPA effectively promotes the intramolecular coupling of unactivated olefinic ketones by a reductive ketyl-olefin radical-cyclization process.The reaction is quite general for the formation of 5- and 6-membered carbocycles and even provides modest yields in less facile cyclization processes as evidenced by the generation of methylcyclooctanol via an 8-endo cyclization.Sequential radical cyclization-intermolecular nucleophilic addition/substitution processes set the SmI2 reaction apart from its radical-chain, photochemical, and electrochemical counterparts.In addition to delineating the synthetic potential of this reaction, the role played by HMPA in enhancing SmI2 reactivity has been further refined, and a model correlating the high diastereoselectivity and product distribution in SmI2-promoted reductive coupling processes with HMPA concentration has been established.
