Using Modern Synthetic Techniques to Conduct Difficult Transformations Relating to the Agrochemical Industry

Abstract

The work described in this dissertation is divided into three chapters each discussing independent projects where either gas-liquid flow technology or microwave reactor technology was applied to organic synthesis.

The first chapter describes the flow hydroxy-carbonylation of ortho-substituted iodo arenes. It was found that through the use of a “tube-in-tube” reactor to introduce the carbon monoxide gas to the reaction mixture, a number of ortho-substituted carboxylic acids could be prepared. The second part of this chapter deals with the synthesis of a herbicidal intermediate which was prepared through the carboxylation reaction with carbon dioxide (dry ice). A parallel flow process for the preparation of this herbicidal intermediate was also developed. This work was reported in one publication.

In the second chapter another gas; oxygen, was used in continuous flow as an oxidant in the Chan-Lam reaction. The first part of this chapter demonstrates how a continuous process for the synthesis of a herbicidal intermediate was developed through an optimised catalytic Chan-Lam reaction which was also shown to consistently work at different scales. In the second part a more generalised catalytic Chan-Lam reaction was optimised and this lead to a small collection of C-N coupled products. This work was published in one publication.

The use of 1,4-dithain-2,5-diol as a precursor for 2-mercaptoacetaldehyde was used as a building block for the synthesis of thiazoles in the third chapter. Using microwave reactor technology the optimised reaction conditions for this novel transformation was quickly achieved. A bifurcation pathway was discovered where either 2-aminothiophens or 2-substiuted thiazoles were prepared, which was demonstrated through the synthesis of a small library of compounds. This work was disclosed in two separate publications.