Novel derivatives of DPP and related heterocycles

Abstract

This thesis discusses the synthesis of new organic, heterocyclic materials for potential application as pigments. Chapter 1 comprises an introduction to the field of pigment and dye chemistry, discussing the rudimentary elements of colour theory, before advancing to a review of the pertinent literature regarding high performance organic pigments. In particular, the development of 1,4-diketopyrrolo[3,4-c]pyrrole (DPP) pigments is described and the central objective of synthesising alkenyl-DPPs is outlined. Chapters 2 and 3 describe synthetic efforts towards alkenyl-DPPs, employing retro Diels-Alder methodology. The reactions involving the furan-acrylonitrile adduct as the nitrile component in the standard DPP synthesis led mainly to aromatisation of the bicyclic system and the cyclopentadiene-acrylonitrile adduct failed to react altogether. The explanation for this failure has been investigated. In the course of this these studies, several DPPs incorporating a secondary alkyl substituent were prepared, not least a novel cyclohexenyl-DPP. Chapter 4 describes the use of α β-unsaturated nitriles in the standard DPP synthesis. These behaved as Michael acceptors and in the case of cinnamonitriles led to a new family of coloured materials, namely substituted 4-hydroxy-2/7- cyclopenta[c]pyrrol-1-one-5-carbonitriles. Chapter 5 describes the corresponding reaction of cinnamate esters, but in these cases bicyclic systems were not formed. The reactions are analogous to Claisen acylations and the stereochemistry of the products varied according to the substituents. Chapter 6 contains the detailed experimental work for these investigations and concludes with a portfolio of X-ray structural data.