Intramolecular [2+2] Cycloaddition of N-Allylcinnamamines and N-Allylcinnamamides by Visible-Light Photocatalysis
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
Authors: Oderinde, Martins S.; Kempson, James; Smith, Daniel; Meanwell, Nicholas A.; Mao, Edna; Pawluczyk, Joseph; Vetrichelvan, Muthalagu; Pitchai, Manivel; Karmakar, Ananta; Rampulla, Richard; Li, Jianqing; Dhar, T. G. Murali; Mathur, Arvind
Abstract
The visible light-promoted intramolecular [2+2] cycloaddition of N-allylcinnamamines and N-allylcinnamamides in the presence of catalytic amounts of [Ir{dF(CF3)ppy}(2)(dtbpy)]PF6 is reported. Low energy visible light and a high triplet energy iridium-photosensitizer were efficient at promoting the cycloaddition reaction of N-allylcinnamamides and N-allylcinnamamines to the corresponding aryl-3-azabicyclo[3.2.0]heptanones and aryl-3-azabicyclo[3.2.0]heptanes, respectively, with high diastereoselectivity and under mild conditions. Azabicyclic fused rings have been employed as surrogates for piperidine motifs in drug discovery. Functional groups useful for deployment and/or elaboration in drug discovery campaigns were all shown to be tolerated, including halides, CF3, cyanide, ester, acetamide, acetate, CH3O, pyridyl, furan, carbamate, tosyl, benzyl, and benzoate.
Temperature-Scanning Reaction Protocol Offers Insights into Activation Parameters in the Buchwald-Hartwig Pd-Catalyzed Amination of Aryl Halides
ACS CATALYSIS
Authors: Schmidt, Olivia P.; Blackmond, Donna G.
Abstract
A temperature-scanning reaction (TSR) protocol allows deconvolution of the driving forces of concentration and temperature in a single experiment, demonstrated here for the Buchwald-Hartwig amination reaction using different amine substrates that exhibit different rate-determining steps. An Eyring analysis reveals that the observed reactivity differences between 1-hexylamine and benzophenone hydrazone are related primarily to the different contributions of activation entropy in the two cases. This TSR protocol combined with other in situ kinetic methodologies including reaction progress kinetic analysis and variable time normalization analysis provides a rapid and comprehensive mechanistic picture of complex multistep catalytic reactions.
COA
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