Discovery and Development of New Metal Catalyzed Methods to Key Building Blocks in Organic Synthesis
This dissertation will provide the details of metal-catalyzed transformations to key building blocks in organic synthesis. In particular the synthesis of alkynes, allenes and aryl boronic acids will be described. The first transformation was achieved through a catalytic decarboxylation/elimination of (E)-enol triflates bearing an allylic ester to obtain alkynes via palladium catalysis. This methodology allows for a general, mild and robust synthesis of three different alkynes including internal, terminal and halogenated alkynes. The second transformation demonstrates the use of alkynes and aryl chlorides in the presence of a palladium catalyst to synthesize tri-substituted allenes. This process takes advantage of a vinyl-Pd(II) species which can undergo a β-hydride elimination to access the desired allene. Lastly, borylation reactions of aryl halides and pseudo aryl halides utilizing both palladium and nickel catalysis will be described. This process highlights the importance of halide sequestering during the course of the borylation reaction resulting in catalyst loadings as low as 0.01 mol %. Furthermore, the utility of the borylation transformation will be demonstrated through late-stage functionalization and tandem/telescoping reactions.