A Conia‐Ene‐Type Cyclization under Basic Conditions Enables an Efficient Synthesis of (−)‐Lycoposerramine R
作者:Felix W. W. Hartrampf、Takayuki Furukawa、Dirk Trauner
DOI:10.1002/anie.201610021
日期:2017.1.16
An enantioselective total synthesis of the Lycopodium alkaloid lycoposerramine R is presented. It relies on a base‐mediated cyclization that resembles the Conia‐ene reaction of ynones and gold‐catalyzed variants thereof. Thus, hydrindanones and other functionalized ring systems bearing an exocyclic alkene can be rapidly accessed at room temperature without noble metal catalysis or substrate preactivation
Asymmetric Hydrogenation of α,α′-Disubstituted Cycloketones through Dynamic Kinetic Resolution: An Efficient Construction of Chiral Diols with Three Contiguous Stereocenters
Chiral diols with threecontiguousstereocenters were synthesized by a highly enantioselective ruthenium‐catalyzedasymmetric hydrogenation of racemic α,α′‐disubstituted cycloketones involving dynamic kineticresolution. This new catalytic asymmetric method provides a concise route to the alkaloid (+)‐γ‐lycorane.
An aqueous chemoenzymatic cascade reaction combining Pd-catalyzed C–C formation and enzymatic CC asymmetric hydrogenation (AH) was developed for enantioselective synthesis of tertiary α-aryl cycloketones in good yields and excellent enantioselectivities. The stereopreference of the enzyme in AH of α-aryl cyclohexenones was studied. An enantiocomplementary enzyme was obtained by site-directed mutation
An expeditious synthesis of α-aryl- and α-alkynylcyclohexenones is described and illustrated by palladium-catalyzed cross-coupling reaction of cyclic α-iodoenones with potassium aryl-trifluoroborate salts. This procedure offers easy access to α-arylated and alkynylated cyclohexenones functionalized with electrondonor and -acceptor substituents in good yields.
Dynamic Kinetic Resolution of γ-Substituted Cyclic β-Ketoesters via Asymmetric Hydrogenation: Constructing Chiral Cyclic β-Hydroxyesters with Three Contiguous Stereocenters
An efficient asymmetric hydrogenation of racemic γ-substituted cyclic β-ketoesters via dynamic kineticresolution to provide chiral cyclic β-hydroxy esters with threecontiguousstereocenters is reported. Using a chiral spiro iridium catalyst (R)-5 (Ir-SpiroSAP), a series of racemic γ-aryl/alkyl substituted cyclic β-ketoesters were hydrogenated to the corresponding chiral cyclic β-hydroxy esters in