Using modern synthetic techniques to conduct difficult transformations relating to the agrochemical industry

• Main Author: Mallia, Carl James
• Published: Durham University 2016
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.693506

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.