61558-99-4Relevant academic research and scientific papers
Chiral hetero- and carbocyclic compounds from the asymmetric hydrogenation of cyclic alkenes
Verendel, J. Johan,Li, Jia-Qi,Quan, Xu,Peters, Byron,Zhou, Taigang,Gautun, Odd R.,Govender, Thavendran,Andersson, Pher G.
, p. 6507 - 6513 (2012/06/29)
Several types of chiral hetero- and carbocyclic compounds have been synthesized by using the asymmetric hydrogenation of cyclic alkenes. N,P-Ligated iridium catalysts reduced six-membered cyclic alkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five-membered cyclic alkenes was generally less selective, giving modest enantiomeric excesses. The stereoselectivity of the hydrogenation depended more strongly on the substrate structure for the five- rather than the six-membered cyclic alkenes. The major enantiomer formed in the reduction of six-membered alkenes could be predicted from a selectivity model and isomeric alkenes had complementary enantioselectivity, giving opposite optical isomers upon hydrogenation. The utility of the reaction was demonstrated by using it as a key step in the preparation of chiral 1,3-cis-cyclohexane carboxylates. Copyright
Visible-light-induced photocatalytic reductive transformations of organohalides
Kim, Hyejin,Lee, Chulbom
, p. 12303 - 12306 (2013/02/23)
A photo opportunity: A visible-light-excited iridium catalyst delivers electrons from an amine to an organohalide. The electron transfer then induces reductive scission of the carbon-halogen bond, generating the corresponding alkyl, alkenyl, and aryl radical that can undergo cyclization and hydrodehalogenation reactions. Copyright
Atom Transfer Cyclization Reactions of α-Iodo Esters, Ketones, and Malonates: Examples of Selective 5-Exo, 6-Endo, 6-Exo, and 7-Endo Ring Closures
Curran, Dennis P.,Chang, Chi-Tai
, p. 3140 - 3157 (2007/10/02)
The preparation and free-radical cyclization reactions of unsaturated α-iodo esters, ketones, and malonates have been investigated.For example, sunlamp irradiation of methyl 2-iodo-6-heptenoate in benzene in the presence of 10 mol percent hexabutylditin produces methyl 2-(iodomethyl)cyclopentanecarboxylate (cis and trans) and methyl 3-iodocyclohexanecarboxylate in a ratio of 93/7 in a combined yield of 86percent.The γ-iodo carbonyl products can either be isolated (in most cases) or converted in situ to deiodinated products (with Bu3SnH) or lactones (by heating).Five-, six-, or seven-membered rings selectively form, depending on chain length and alkene substitution.Terminal alkene substituents favor exo cyclization while internal alkene substituents promote endo cyclization.A preference for endo closure is also observed when there is a carbonyl group "inside" the forming ring.A detailed analysis of reaction rates indicates that these isomerizations proceed by an iodine atom transfer chain mechanism, and thus the observed selectivities are due to the kinetic substituent effects.The results contrast the thermodynamically controlled hydrogen atom transfer cyclizations of Julia.A new procedure for the removal of tin byproducts is described.
