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Abstract

A review of [4+ + 2] cationic polar cycloaddition reactions is presented, emphasizing mainly those reactions undergone by large heterocyclic cations. Special attention is paid to the modern mechanistic standpoint for these transformations. The effects that different substituents on either or both the diene or dienophile have on the course of the cycloaddition are discussed in relation to the observed regio- and stereochemistries and to the rates of reaction.

The alkylation of the sodium salts of various 2-(1H)-pyridones, and the intermolecular cycloadditions of several 1-methyl-2-pyridones with dimethylacetylenedicarboxylate (DMAD), are described. Attempts to induce intramolecular cycloaddition reactions across the diene backbone of several 2-pyridones are included
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A recently reported synthesis of 6-substituted-4-hydroxy-2-pyridones has been extensively investigated, and the possibility of their alkylation pursued. Their reactions with DMAD are also dealt with.

A novel alkylation procedure of isoquinoline and its 3-methyl analogue is communicated, and has been used in the synthesis of isoquinolinium salts potentially able to undergo intramolecular Diels-Alder reactions. The thermolyses of these salts are described, together with the intermolecular cycloaddition reactions of simple 2,3-dimethylisoquinolinium salts with alkyl vinyl ethers. Further transformation of the primary adducts obtained has led to several previously unknown structures.

An appendix containing the 13C n.m.r. data of many of the more interesting structures obtained throughout this work has been included.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science Q Science > QD Chemistry
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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