Rhodium-Catalyzed, Enantioselective Hydroacylation of <i>ortho</i>-Allylbenzaldehydes
作者:Kirsten F. Johnson、Adam C. Schmidt、Levi M. Stanley
DOI:10.1021/acs.orglett.5b02559
日期:2015.10.2
The development of a rhodiumcatalyst for endo- and enantioselective hydroacylation of ortho-allylbenzaldehydes is reported. A catalyst generated in situ from [Rh(COD)Cl]2, (R)-DTBM-SEGPHOS, and NaBARF promotes the desired hydroacylation reactions and minimizes the formation of byproducts from competitive alkene isomerization and ene/dehydration pathways. These rhodium-catalyzed processes generate
bicyclic core structures with up to three stereocenters within a single step. Herein, this concept is combined with the chemistry of chiral Brønsted acid bound ortho-quinonemethideimines to generate a range of interesting fused tetrahydroquinolines in a diastereo- and enantioselective manner.
Iridium(I)-Catalyzed Intramolecular Hydrocarbonation of Alkenes: Efficient Access to Cyclic Systems Bearing Quaternary Stereocenters
作者:David F. Fernández、Moisés Gulías、José L. Mascareñas、Fernando López
DOI:10.1002/anie.201705105
日期:2017.8.1
wide variety of cyclic systems featuring methyl-substituted quaternary stereocenters is described. The method relies on the use of a cationic IrI–bisphosphine catalyst, which promotes a carboxamide-assisted activation of an olefinic C(sp2)−H bond followed by exo-cyclization to a tethered 1,1-disubstituted alkene. The extension of the method to aromatic and heteroaromatic C−H bonds, as well as developments
Visible-light induced generation of bifunctional nitrogen-centered radicals: a concise synthetic strategy to construct bicyclo[3.2.1] octane and azepane cores
A photocatalytic tandem cyclization of o-alkenylbenzaldehydes using pyridinium salts as the amination reagent is described. A variety of valuable seven-membered nitrogenous heterocyclic skeletons are prepared in modest to excellent yields in concise one-step. This transformation features mild reaction conditions and exceptional functional group tolerance. In addition, combining control experiments and density functional theory (DFT) calculations on the mechanism can explain the reaction selectivity.
A Synthesis of 6-Azabicyclo[3.2.1]octanes. The Role of <i>N</i>-Substitution
作者:Aravinda B. Pulipaka、Stephen C. Bergmeier
DOI:10.1021/jo702444c
日期:2008.2.1
The intramolecular cyclization reactions of aziridines with π-nucleophiles can be a useful route to a number of heterocyclic and carbocyclic ringsystems. We were particularly interested in the use of this cyclization reaction for the synthesis of 6-azabicyclo[3.2.1]octanes. We report here the development of a new synthesis of the aziridine necessary for the aziridine−π-nucleophile cyclization. We