Synthesis of some optically active terpenoid-derived thioamides

GRAPHICAL ABSTRACT

ABSTRACT

Several terpenoid-derived thioamides have been synthesized in the reactions taking advantage of the electrophilicity of the carbonyl function in terpenones and the nucleophilicity of the terpenone lithium enolates. The optically active β-hydroxythioamide derivatives 4, 6, 8, 10, 12 have been obtained by reacting the thioacetanilide dianion 2 with terpenones. The reaction of the enolate anions of (-)-menthone and (1R)-(+)-camphor with phenyl isothiocyanate gave rise to the formation of the corresponding β-ketothioamides 13, 14. In a multicomponent reaction (MCRs) with benzylamine and formaldehyde, 14 yielded the spirohexahydropyrimidine 15.

KEYWORDS:

• Thioamide
• thioacetanilide dianion
• terpenone
• addition reaction
• spirohexahydropyrimidine

Acknowledgments

We express our thanks to Professor Jerzy Lange of the Warsaw University of Technology for helpful discussions and assistance with the manuscript.