Stereospecific Cross-Coupling Reactions of Aryl-Substituted Tetrahydrofurans, Tetrahydropyrans, and Lactones
作者:Emily J. Tollefson、David D. Dawson、Charlotte A. Osborne、Elizabeth R. Jarvo
DOI:10.1021/ja5076426
日期:2014.10.22
complex stereochemical arrays. Stereoselective synthesis of the cyclic template is utilized to control relative configuration; subsequent stereospecific nickel-catalyzed ring-opening affords the acyclic product. Aryl-substituted tetrahydrofurans and tetrahydropyrans undergo nickel-catalyzed Kumada-type coupling with a range of Grignard reagents to furnish acyclic alcohols with high diastereoselectivity
Ruthenium- and Enzyme-Catalyzed Dynamic Kinetic Asymmetric Transformation of 1,4-Diols: Synthesis of <i>γ</i>-Hydroxy Ketones
作者:Belén Martín-Matute、Jan-E. Bäckvall
DOI:10.1021/jo048511h
日期:2004.12.1
Enzymatic kinetic resolution of unsymmetrical 1,4-diols in combination with a ruthenium-catalyzed hydrogen transfer process led to a dynamickineticasymmetrictransformation (DYKAT) of the least hindered alcohol. Oxidation of the second hydroxy group takes place under the reaction conditions leading to the formation of γ-acetoxy ketones in high enantiomeric purity.
enantioconvergent access to chiral N-heterocycles directly from simple racemic diols and primary amines, through a highly economical borrowing hydrogen annulation. The identification of a chiral amine-derived iridacycle catalyst was the key for achieving high efficiency and enantioselectivity in the one-step construction of two C–N bonds. This catalytic method enabled a rapid access to a wide range of
1,4‐ and 1,5‐diols undergo cyclodehydration upon treatment with cationic N‐heterocyclic carbene (NHC)–IrIII complexes to give tetrahydrofurans and tetrahydropyrans, respectively. The mechanism was investigated, and a metal‐hydride‐driven pathway was proposed for all substrates, except for very electron‐rich ones. This contrasts with the well‐established classical pathways that involve nucleophilic