The Synthesis of Novel Cyclohexyne Precursors for an Intramolecular Pauson-Khand Type Reaction

Abstract

Strained cycloalkynes, particularly cyclohexyne and cyclopentyne, are interesting synthetic intermediates that have largely been overlooked in organic synthesis. In addition, the Pauson-Khand reaction is a formal [2+2+1] cycloaddition that utilizes an alkene, an alkyne, and carbon monoxide. The use of strained cycloalkynes in the Pauson-Khand reaction has been surveyed, but it has not been performed successfully for cyclohexyne and cyclopentyne containing substrates. Design and optimization of such a reaction could lead to the swift synthesis of a polycyclic scaffold that is found in many natural products, many of which have not been synthesized. This thesis presents several approaches to a new class of vinyl triflates that could serve as cyclohexyne precursors for the Pauson-Khand reaction. While only a few cyclohexyne precursors were successfully synthesized, a synthetic route is presented that can access this class of molecules in moderate yield over three steps. In addition, use of these cyclohexyne precursors in the Pauson-Khand reaction led to the formation of the desired polycyclic product.