Radical Coupling Reactions Research Of 2-Chloro-1,3-dithiane With Aldehydes And Alkynes, And The Method Of Synthesis Multisubstituted Furans

Dithiane compounds serve as valuable synthetic intermediates in the ?eld of natural product synthesis and can participate in a range of useful transformations. Recently, our group introduced the ?rst protocol for the direct cross-coupling of alkene involving a novel dithianyl radical coupling mechanism. On this basis, the radical coupling reactions of 2-chloro-1,3-dithiane with aldehydes and alkynes to construct substituted-dithiane compounds was researched. Meanwhile, the synthesis of multisubstituted furans by β-chloro-vinyl dithianes cyclization with aldehydes also was studied. This thesis is divided in three parts.Firstly, FeCl3 catalyzed radical coupling reaction of 2-chloro-1,3-dithiane with aldehydes was stuied. 15 mol% of FeCl3 at 50 oC in 1,2-dichloroethane(DCE) lead to dithianes in good to excellent yields. The reaction mechanism has been studied through radical process. This methodology is bene?cial due to mildness of the reaction conditions.Secondly, the mesylate catalyzed radical coupling reaction of 2-chloro-1,3-dithiane with alkynes was invistigated. 1.2 equiv of mesylate at 50 oC in DCE to lead to β-keto-dithianes. The versatile method tolerates broad substrate scope and good functional group compatibility. And the radical coupling process results in good to excellent yields.Finally, a new transition-metal-free tactic for convergent, one-pot synthesis of multisubstituted furans by β-chloro-vinyl dithianes cyclization with aldehydes was presented. 1.2 equiv of t-BuOK at room temperature in THF to lead to multisubstituted furans in high yield.