SYNTHESIS OF ALLYLIC SYNTHONS AND APPLICATION OF PYRROLE THIOCARBOXYLIC ACIDS IN THE SYNTHESIS OF PYRROLE-IMIDAZOLE ALKALOIDS

Abstract

**Please note that the full text is embargoed until 5/16/2024** ABSTRACT: The first part of this dissertation describes the synthesis of allylic compounds from terminal alkenes without the use of any catalysts or oxidants. One of the most versatile molecules in organic chemistry is allylic compounds. Their importance arises from their miscellaneous reactivity which makes them attractive to organic chemists. They are found in several molecules that have medicinal and synthetic utilities. The preparations of allylic compounds have been majorly through transition metal catalyzed process. The second part describes the formation of pyrrole-carboxamide in pyrrole-imidazole alkaloids. Pyrroleimidazole alkaloids have gained attention of synthetic chemists due to their potential therapeutical applications and their complex structural framework which is nitrogen dense. Chapter 1 provides a survey of literature for the synthesis of allylic compounds and provides context for our contribution. Chapter 2 describes the development of a one-pot, two-step protocol for the transformation of transformed aryl substituted terminal alkenes into allylic azides and amines using sodium azide or primary, secondary, and tertiary amine nucleophiles. The scope of this transition metal-free method was established using a variety of aryl substituted terminal alkenes providing a highly regio- and stereoselective synthesis of linear (E) isomer azides and amines in good yield. This method was applied to the synthesis of cinnarizine. The synthetic utility and feasibility of the protocol on gram-scale was demonstrated using two different azides. Chapter 3 details the development of an approach for the synthesis of α-styrene compounds bearing several useful functional groups. We explored varying classes of nucleophiles: carbon, nitrogen, oxygen, and sulfur-centered systems; this methodology is tolerant to wide scope of nucleophile. The nucleophilic addition occurs at room temperature providing moderate to good yields of the products. This transformation avoided transition metals and proceeded under generally benign conditions. Chapter 4 provides an overview of the pyrrole-imidazole alkaloids, with focus on syntheses describing the installation of pyrrole carboxamide linkage. Chapter 5 presents a novel, easy-to-perform, less sensitive method for the synthesis of pyrrole thiocarboxylic acids, which has been elusive prior to this discovery. The pyrrole thioacids have been used to construct pyrrole-carboxamides via thioacid azide ligation. This has been employed in the synthesis of clathoridin derivatives without allylic transposition. We further coupled acyl imidazoles with amines to create amide linkage with benign reaction conditions.