The Diels-Alder reaction was discovered in 1928 and has become the most efficient and practical method for the synthesis of six-membered carbocyclic and heterocyclic rings. This thesis comprises three chapters of results and discussion with the Diels-Alder reaction as a theme. Chapter 2 details an investigation of endo:exo selectivity in the Diels-Alder reactions of 1,3-butadiene. Chapter 3 explores aspects of the intramolecular Diels-Alder reactions of some substituted 1,3,8-nonatrienes, and

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... apter 4 describes the domino Diels-Alder reactions of 1,4-diiodo-1,3-butadiene. The Diels-Alder reaction is powerful, general, and widely used in chemical synthesis, and it is well known that many Diels-Alder reactions exhibit endo selectivity, in accord with Alder's empirical rule. The origins of endo:exo selectivity in the Diels-Alder reaction, however, are not completely understood and there is a dearth of experimental evidence concerning the Diels-Alder reactions of the archetypal 1,3-diene, 1,3- butadiene. Chapter 2 describes a study of the Diels-Alder reactions of an isotopically labelled 1,3-butadiene with a range of simple dienophiles, allowing the endo:exo selectivities of these important reactions to be determined for the first time. The experimental data shed light on the origins of endo:exo selectivity in the Diels-Alder reaction and will serve as an important reference for future computational investigations in this area. The intramolecular Diels-Alder reaction shares many of the virtues of its intermolecular counterpart, however its use in chemical synthesis is limited because intramolecular Diels-Alder reactivity and stereoselectivity are often governed by subtle factors, and can be very difficult to predict. As part of a comprehensive experimental and computational collaboration, Chapter 3 describes an investigation of the heat and Lewis acid promoted intramolecular Diels-Alder reactions of some ether tethered 1,3,8-nonatrienes. Also presented are the results of a rate study and a kinetic isotope effect stu [...]