| Interest in the chemistry of carbazoles and related annulated systems is increasing continuously as some of these compounds, both naturally occurring and synthetic, exhibit pharmacological activity. The [4 + 2]-cycloadditions of 2- and 3-vinylindoles have proven to be a synthetically efficient concept for the construction of selectively functionalized carbazole derivatives because cycloaddition reactions with vinyl-heterocycles give condensed heterocycles with substitution patterns which are not accessible so directly by other routes. The limits to the synthetic potential of this reaction type, however, have by no means been defined. Also, comprehensive knowledge of alternative pathways for, or reactions competing directly with, the cycloadditions when using vinyl-heterocycles and dienophiles is still lacking. While both 2- and 3-vinylindoles have been reported to undergo Diels-Alder reactions, only the reactions of 3-vinylindoles will be discussed.; The concept of constructing substituted carbazoles and their derivatives via Diels-Alder reactions with 3-vinylindoles relies heavily on the ease at which one has access to the necessary 3-vinylindoles. Among the synthetic methods available for the construction of 3-vinylindoles, the Knoevenagel, Perkin, and aldol condensations, the Cope elimination, Wittig and Horner-Emmons-Wadsworth olefinations, reduction/dehydration, base-mediated enolization followed by subsequent trapping, Michael addition with electron deficient acetylenes and ethylenes, and Pd-catalyzed vinylation are considered as reliable standard methods. However, some drawbacks may be encountered in using these methods, such as low yields, harsh reaction conditions, and tedious workup procedures. It is desirable, therefore, to develop additional practical methods for the synthesis of these heterocyclic-1,3-diene systems. We have demonstrated that both the Peterson olefination and the Nysted reagent are excellent methods/reagents for preparing terminally-unsubstituted 3-vinylindoles. In addition, we have prepared a number of 3-vinylindoles by classical methods and have explored their reactivity.; The Diels-Alder reactions of 1',2' -disubstituted, 1'-substituted, 2' -substituted, and unsubstituted 3-vinylindoles with various carbo- and heterodienophiles are discussed in this thesis. |
