Date of Award
Doctor of Philosophy (PhD)
Yi, Chae S.
Gardinier, James R.
Despite their outstanding achievements, the requirement of preformed functional groups and wasteful byproduct formation are inherent disadvantages associated with the transition metal catalyzed cross-coupling methods. Inspired by the needs for green and sustainable chemistry, transition metal catalyzed dehydrogenative and dehydrative coupling methods have been recognized as environmentally sustainable and atom economical synthetic routes for the new C-C bond formation. The catalytic activation of C-H and C-O bonds allows the formation of coupling products from ubiquitous hydrocarbon substrates by releasing hydrogen or water byproduct. However, these novel protocols require relatively harsh conditions due to their low reactivity of C-H and C-O bonds, and difficulty in controlling regioselectivity. The development of new catalytic C-H bond activation methods is highly desirable for the selective C-C formation reactions. The cationic ruthenium-hydride complex was found to be a highly effective catalyst for the dehydrogenative and dehydrative C-H coupling reactions of simple arenes with alcohols and carbonyl compounds. The dehydrogenative coupling reaction of phenols with aldehydes formed the 2-acylphenols without using any metal oxidant or forming wasteful byproducts. The mechanistic studies suggested that the aldehyde substrate was served as both the coupling partner and hydrogen acceptor. The coupling method was successfully extended to the synthesis of 2H-chromene derivatives by using α,β-unsaturated aldehydes. The cationic ruthenium-hydride complex was found to exhibit uniquely high activity for the coupling reaction of phenols with ketones to form synthetically useful 2-vinylphenols. The coupling of phenols with linear ketones led to a highly (Z)-selective formation of trisubstituted olefins. We also developed the catalytic synthesis of biologically important indole and quinoline derivatives from the coupling reaction of arylamines with diols. A broad range of substrates was demonstrated to afford the regioselective N-heteroannulated products. The deuterium labeling study and control experiments were performed to discern the mechanistic pathway.
Available for download on Friday, November 10, 2017