The reaction of C-alkylation of eudesmanolide (–)-α-santonin

Abstract

This article is concerned with sesquiterpene γ-lactones of the eudesman structure, which is promising class of natural organic compounds and characterized by a wide spectrum of physiological activity. Stereoselective synthesis of new practically significant 4α(ethyl)-3-keto-trans-eudesm-1(2),5(6)-diene-6,12-olide(C4-α-ethylsantonin) was carried out at room temperature in argon atmosphere by interaction of eudesmanolide (–)-α-santonin and an organohalide in presence of a strong base: tert-butyl-potassium: dimethylsulfoxide: tert-butyl alcohol. The yield was 50 %. The spatial structure of the synthesized C4-α-ethyl-santonin was established by 1H NMR-, 2D NMR (COZY, NOESY), mass spectrometry and X-ray analysis. According to the results of X-ray analysis there has been found that the condensed six-membered C4-α-ethyl-santonin cycles are trans-articulated (CH3-10, β-oriented), the ethyl group at C-4 has the α-configuration, and the conformation of six-membered eudesmanolide is characterized as distorted chair-chair. Thus, combination of application in the work of modern physico-chemical and spectroscopic research methods allowed characterization of the structure and properties of the compounds obtained.