Electrophile-Mediated Reactions of Functionalized Propargylic Substrates

Metal‐free halogen, chalcogen, or oxocarbenium ion mediated yne‐carbonyl or yne‐thioxo transformations of a range of N‐ and O‐propargylic compounds have been studied. This investigation has led to the development of a mild, economic, and effective method for the synthesis of functionalized 4H‐1,3‐oxazines, 4H‐1,3‐thiazines, 4,5‐dihydrothiazoles, and α‐substituted enones. The structure of the propargylic substrate and the nature of electrophile influence both the outcome and regioselectivity of processes. Metal‐free electrophile‐mediated transformations of various N‐ and O‐propargylic compounds have been studied. The scope and limitations of these reactions have been evaluated by using a broad range of substrates.