Domino Cyclization Of Allylic Phosphonium Ylide With Thioaurone

Benzothiophene derivatives have good biological activities and extensive practical applications in material chemistry、medicinal chemistry and other fields.Therefore,the development of novel and efficient methods for the synthesis of benzothiophene derivatives have been received a widespread attention.In this paper,by using the specific reactivity of allylic phosphonium ylide in the cyclization reaction,efficiently constructing benzothiophene derivatives in a novel reaction mode with different thioaurone substrates under mild conditions have been developed,which also provide new ideas and models for the synthesis of complex heterocyclic compounds.1)The DBU-catalyzed thioaurone and crotonic acid-derived allylic phosphonium ylide were studied to efficiently construct 1,4-dihydrodibenzothiophene derivatives via the Michael addition-Wittig reaction mode.The mild reaction conditions and excellent substrate suitability make the synthesis of 1,4-dihydrodibenzothiophene compounds have an important application value in organic synthesis methodology and materials science.2)The DBU-catalyzed thioaurone and sorbic acid-derived allyl phosphonium ylide were subjected to the Michael addition-Wittig reaction mode,followed by intramolecular aromatization to form a dibenzothiophene ring structure.This domino reaction provides a method for rapidly constructing a dibenzothiophene ring in a simple and mild reaction mode,has an extremely important research value in organic synthesis.3)Design and synthesize two new types of thioaurone derivatives,which are catalyzed by alkaloid and inorganic base,respectively,then via a quadruple domino cyclization reaction with crotonic acid-derived allylic phosphonium ylide.The similar skeleton structure of the two kinds products of the oxygen-containing umbrella-like tricyclic benzothiophene ring was synthesized and characterized in good yields and moderate to excellent stereoselectivity,and the substrate reaction and substrate derivatization were studied.A total of 131 new compounds were synthesized in this paper.All new compounds were identified by ¹H NMR,¹³C NMR,IR,HRMS,m.p.（solid）and representative compounds were determined by X-ray single crystal diffraction analysis.