Synthetic transformations of sesquiterpene lactones. IV.* Synthesis and transformations of gem-dichlorocyclopropyl-substituted isoalantolactone derivatives

Syntheses Based on 3,4α-Epoxy-1,5,7α,6β(H)-guai-10(14),11(13)-dien-6,12-olide

The sesquiterpene γ-lactone estafiatin 1, the molecule of which has a structure of 3,4α-epoxy-1,5,7α,6β(H)-guai-10(14),11(13)-dien-6,12-olide, is characteristic of plants of the genera Achillea L. and Artemisia L. of the Asteraceae family. This article presents the results of chemical modification for three reaction centers of the estafiatin molecule 1: epoxy cycle, exomethylene group conjugated with γ-lactone carbonyl, and exomethylene group in position C10=C14; and at the same time 33 new derivatives were synthesized, the structures of which were established based on physicochemical constants, spectral data (IR-, PMR-, ¹³C-NMR), and X-ray diffraction analysis. The stereo- and regiospecificity, as well as the chemoselectivity of the reaction based on estafiatin molecule 1, are discussed. The reactivity of the substrate is significantly influenced by the stereochemistry of its molecule, the nature of the reagent, and the reaction medium. Based on the results of in silico screening, derivatives of estafiatin with high binding energies for both DNA-topoisomerase I and DNA-topoisomerase II were identified. The values of the inhibitory dose of IC₅₀ for estafiatin 1 and its derivatives were determined on cell lines of eight types of tumors. in vivo experiments of the samples made it possible to establish that estafiatin 1 and its derivatives have pronounced antitumor activity against Pliss lymphosarcoma, Walker’s carcinosarcoma, sarcoma 45, sarcoma-180, alveolar liver cancer PC-1, leukemia P-388 and L-1210, and sarcoma-45 resistant to 5-fluorouracil.

Recent advances in the syntheses, transformations and applications of 1,1-dihalocyclopropanes

gem-Dihalocyclopropanes have wide-spread applications in organic synthesis due to their versatile chemistry. They can serve as substrates for a large range of useful materials such as natural products, alkaloids, cyclopropanes, heterocycles, aromatic ring systems etc. Normally the dihalocyclopropanes are prepared by the addition of dihalocarbene to alkene, but due to the great synthetic efficacy of gem-dihalocyclopropanes a number of methods have been developed for their synthesis. Generally gem-dihalocyclopropanes exist as strained cyclic systems with astonishing kinetic stability. They are capable of undergoing transformations leading to a variety of products which have potential applications in various synthetic organic chemistry fields.