Resumo

MENDOZA, Jorge A. et al. Synthesis, Structural, and Theoretical Study of New β-Heterosubstituted Captodative Olefins 1-Acetylvinyl Arenecarboxylates. Rev. Soc. Quím. Méx [online]. 2003, vol.47, n.2, pp.108-116. ISSN 0583-7693.

A new series of β-heterosubstituted captodative olefins 1-acetylvinyl arenecarboxylates (7a and 10a-10h) has been prepared, by introducing nitrogen or sulphur as heteroatoms substituted by alkyl and aryl groups. Three preparation methods were evaluated by modifying the leaving group of the starting material, as well as the nucleophilic character of the adding thiols. All of them were efficient and stereoselective, providing the desired alkenes in good yields and with the Z configuration of the double bond. Ab initio calculations (HF/6-31G*) of the FMOs, of some of the beta amino and bromo olefins, explained their experimental reactivity in Diels-Alder additions with respect to the unsubstituted olefin 1a. It also appears that the HOMO and LUMO energies of the beta sulphur analogues are governed by the particular electronic features of the sulphur atom, and that their very low reactivity before a diene is due to steric hindrance. A comparison between bond distances obtained by X-ray crystallography of different β-substituted and unsubstituted olefins seems to correlate with the delocalization effect of the heteroatom lone electron pair for the bromo and amino β-substituted olefins.

Palavras-chave : Captodative olefin; structure; reactivity.