Detours in the Development of the Organocatalytic Diels-Alder Reactions of Vinylboronic Compounds: A Dead End?

Abstract

Attempts to improve the organocatalytic Diels-Alder reactions of vinylboronic compounds are described. Further experiments, theoretical calculations and NMR studies were performed to optimize the existing procedure and analyze the reactivity of the reactive intermediate and the ligand-exchange process. In particular, the relationship between the structure and the performance of the organocatalysts was studied theoretically and experimentally. Although the catalytic activity of the α-hydroxyacids could not be improved much, a deeper insight has been gained, which might be useful for the development of other organocatalytic reactions of organoboron compounds.