Theses and Dissertations
ORCID
https://orcid.org/0000-0003-2813-4441
Issuing Body
Mississippi State University
Advisor
Cui, Xin
Committee Member
Montiel-Palma, Virginia
Committee Member
Creutz, Sidney
Committee Member
Munoz-Hernandez, Miguel
Committee Member
Emerson, Joseph P.
Date of Degree
12-13-2024
Original embargo terms
Complete embargo 2 years
Document Type
Dissertation - Open Access
Major
Chemistry
Degree Name
Doctor of Philosophy (Ph.D.)
College
College of Arts and Sciences
Department
Department of Chemistry
Abstract
Transition metal-catalyzed C–H bond activation and hydroarylation have attracted significant attention, especially with metals like palladium, rhodium, and iridium. Despite being more affordable and readily available, ruthenium-catalyzed C–H activation and hydroarylation have not yet been extensively developed, especially in terms of enantioselectivity. This dissertation focuses on developing new strategies to address the current challenges in ruthenium-catalyzed hydroarylation via stereoselective C–H bond activation using imines as transient directing groups. Chapter I presents an overview of ruthenium-catalyzed C–H functionalization, highlighting various strategies, challenges, and limitations in C–H activation and hydroarylation. It also discusses the current advancements in transient directing group strategy. Chapter II outlines a novel approach for synthesizing N-fused polycyclic indole derivatives and related polycyclic analogs through Ru(II)-catalyzed C–H bond activation and intramolecular hydroarylation. A series of polycyclic indoles with 3-formyl groups were synthesized in good to high yield. Different aliphatic and aromatic amines were examined for forming a transient directing group with the aldehydes, with 1-naphthylamine proving particularly effective. DFT calculations were performed to gain further insight into the role of the transient directing group. Chapter III describes Ru(II)-catalyzed transient imine-directed enantioselective intermolecular hydroarylation of bicycloalkenes via C–H activation, yielding bicyclic aldehyde derivatives with up to 86% yield and excellent enantioselectivity. The use of chiral 1-(9-phenanthryl)ethylamine, combined with [Ru(p-cymene)Cl2]2 was crucial for achieving high enantioselectivity. Further transformation of desired bicyclic products enables the synthesis of highly enantioselective biaryl aldehydes, which are valuable precursors for asymmetric synthesis. Chapter IV focuses on the further development of the transient directing group strategy. A series of new ruthenium catalysts were developed by combining them with chiral amines to address challenges related to atom and step economy in C–H activation. Although these catalysts did not show successful catalytic performance, this preliminary study provides a foundation for future research. Chapter V explores asymmetric ruthenium-catalyzed C–H activation and intramolecular hydroarylation using desymmetrization. The reaction showed a lower conversion, with yields around 46%, likely due to the formation of an unconfirmed intermediate. However, it achieved excellent enantioselectivity, with a 91% ee.
Recommended Citation
Dissanayake Mudiyanselage, Nirosh Udayanga, "Ru(II)-catalyzed intramolecular and intermolecular hydroarylation via stereoselective C–H bond activation" (2024). Theses and Dissertations. 6421.
https://scholarsjunction.msstate.edu/td/6421