Research Projects

The proposal describes a novel approach for asymmetric unsymmetrical functionalization of multiple C-H bonds using a chiral sulfoximine directing group (DG) anchored transition-metal (TM) catalyst. While mono-fold asymmetric C-H activation/functionalization has gained significant progress, asymmetric multi-fold C-H activations are underdeveloped. The proposal aims to develop a chiral transformable directing group (CTfDG)-aided asymmetric multiple C-H functionalizations that enables the recovery and reusability of the chiral DG. The approach entails the sequential execution of two-fold C-H functionalizations, with the initial functionalization performed at a low temperature to preserve the overall stereoselectivity, and the second functionalization carried out at a high temperature, which poses a significant challenge as both steps need to be synchronized perfectly. The proposal intends to investigate the feasibility of utilizing cost-effective and air-stable half-sandwich Ru(II)-complexes as the TM catalyst. However, the absence of an available coordination site in the Ru(II)-18e-species may pose challenges for the asymmetric C-H insertion process when paired with a pro-chiral coupling partner. The proposed approach could lead to the production of enantioenriched complex molecules. The summary of the synthetic work plan is herein outlined: 1. Chiral Directing Group Assisted Asymmetric Hydroarylation and Sequential Atropo-annulation via Two-fold C-H Activations  one-pot installation of a point chiral and an axially chiral center using a ruthenium-catalyzed asymmetric two-fold unsymmetrical C-H activation. Access to valuable centro-atropo selective dihydrobenzofuran-fused-quinolinone. 2. Ru(II)-Catalyzed Chiral Transformable Directing Group (CTfDG) Enabled Asymmetric Two-fold CH Functionalizations / Annulation with Bulky Alkynes  direct entry to enantioenriched molecules with two chiral centers at distal 1,5-position via the two-fold asymmetric CH functionalization/double atropo-selective annulation with a sterically bulky alkyne. 3. Ru(II)-Catalyzed Chiral Transformable Directing Group (CTfDG) Enabled Asymmetric Two-fold C-H Functionalizations : Annulation with Bulky Alkynes and Spiro Cyclization with Benzoquinone  C-H activation and sequential spiro-lactonization with benzoquinone.  construction of complex molecular skeleton with axially chiral center and spiro-stereocenter 4. Sequential Four-fold Asymmetric C-H Activation/Annulations: Synthesis of [7]-Helicene Derivatives  four-fold asymmetric C-H activation/annulation.  a direct one-pot approach to accessing helical chirality.  utilizes a double chiral sulfoximine DG. 5. Chiral Transformable Sulfoximine Enabled Three Component Arylative Desymmetrization & Sequential Annulation via Two-fold C-H Activations  use of chiral transformable sulfoximine catalyst for asymmetric two-fold C-H activation/functionalizationC(sp3)-H bonds.