A New Class of C2 -Symmetric Chiral Cyclopentadienyl Ligand Derived from Ferrocene Scaffold: Design, Synthesis and Application.

A new class of C2 -symmetric, chiral cyclopentadienyl ligand based on planar chiral ferrocene backbone was developed. A series of its corresponding rhodium(I), iridium(I), and ruthenium(II) complexes were prepared as well. In addition, the rhodium(I) complexes were evaluated in the asymmetric catalytic intramolecular amidoarylation of olefin-tethered benzamides via C-H activation.

Ruthenium(II)-Catalyzed Asymmetric Inert C-H Bond Activation Assisted by a Chiral Transient Directing Group.

A ruthenium(II)-catalyzed asymmetric intramolecular hydroarylation assisted by a chiral transient directing group has been developed. A series of 2,3-dihydrobenzofurans bearing chiral all-carbon quaternary stereocenters have been prepared in remarkably high yields (up to 98 %) and enantioselectivities (up to >99 % ee). By this methodology, a novel asymmetric total synthesis of CB2 receptor agonist MDA7 has been successfully developed.

Divergent Dynamic Kinetic Resolution of a Racemic Mixture of Four Stereoisomers via N-Heterocyclic Carbene Organocatalysis.

Racemic mixtures of four stereoisomers are easily formed via many fundamental organic transformations, but the direct utilities of these mixtures have been less studied and remain large challenges to date. In this work, we introduce a new method, i.e., divergent dynamic kinetic resolution, to achieve the separation of racemic mixtures of four stereoisomers. The hypothesis was proved by using a N-heterocyclic carbene-catalyzed benzoin reaction, which afforded two separable diastereomeric products bearing three consecutive stereocenters with good to excellent enantioselectivties. We believe that this resolution protocol will find applications in more transformations.

Cyclopentadienone Formation from ß,γ-Unsaturated Cyclopentenones and Its Application in Diels-Alder Reactions.

We report that α-acyloxy-ß,γ-unsaturated cyclopentenones were used as starting substrates to make various trisubstituted cyclopentadienones. The substrates are easily available in one step from our previously developed protocol, and the potential of this cyclopentadienone formation method was demonstrated in a series of Diels-Alder reactions, forming dimerization products, dimethyl phthalate derivatives, and polyaryl benzene compounds.