Synthesis of benzophosphole oxides and carbene generation through [3+2] cyclization and preparation of monomers for RAFT and ATRP polymerization

Abstract

This dissertation consists of four main chapters. Chapter I is a brief review of several types of [3+2] cycloaddition reactions and their relationships to the studies described in Chapter 2 and 3.Chapter II discusses the phosphole oxide study stemming from an attempt to generate carbene using the well-studied hexadehydro-Diels-Alder (HDDA) reaction. For this project, trialkynylphosphine, dialkynylphosphine and alkynylphosphine have been synthesized and evaluated as trapping agents in HDDA reactions to synthesize phosphole oxides with different functional groups through a net [3+2] cycloaddition process. Factors that may influence the outcomes of this type of reactions, such as solvent systems, the sizes of alkynylphosphine terminal groups, the sizes of the HDDA benzyne precursor terminal groups, and participation of water, have been studied. Chapter III is a detailed discussion of reactions between alkynylpyridine derivatives and allenes. A recent study of alkynylpyridine derivatives reacting with activated alkynes showed that allenes are promising substrates that may also react with allenes in a similar fashion. Allenes with various levels of activation and substitution patterns have been attempted to study their relative reactivity for the [3+2] carbene generation. The mechanisms which account for different reaction outcomes have been closely examined. Some of the alkynes that are the tautomers of the allenes tested have been used to compare their relative reactivity under the same reaction conditions. Due to the analogous structural features of isocyanates and isothiocyanates, similar reactions have also been attempted with these substrates and the same carbene generation processes have been observed for these experiments as well. The substrate scope may help future researchers explore the possibilities of three-component reactions as well as trapping the carbene intermediate. Chapter IV covers the topic of synthesizing structurally interesting monomers as future polymer building blocks. These monomers derived from a lactone acid, which was prepared through the Diels-Alder reaction between itaconic anhydride and furfuryl alcohol. Different moieties have been incorporated into the said lactone acid to prepare these monomers for both reversible addition fragmentation chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP).