Synthesis And Applications Of 3-(1, 3-Dithian-2-ylidene)-pentane-2, 4-diones

α?Oxoketene dithioacetals are a kind of versatile intermediates used in organic synthesis during the past century. Since Kelber first synthesized theα?benzoyl ketene-(S,S)-acetal in 1910,α?oxo ketene-(S,S)-acetals chemistry has become an important division in organic chemistry through the development of near one hundred years. Particular in recent three decades, quite amount of documents have been published in this area, and several reviews were successively reported to summarize these results. Generally, the reaction types involovingα?oxo ketene-(S,S)-acetals mainly include the regioselective addition-aromatization with organometallic reagents, conjugate addition-cyclization with nitrogen nucleophilic species, nucleophilic reactions ofα?carbon, acting as odorless dithiol equivalents in thioacetalization, Michael additions and [5 + 1] annulation, as well as the synthetic applications based on the above reactions.Among the variousα?oxo ketene-(S,S)-acetals,α,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)-acetal is easier to prepare and bear much more functionalities. From the view of structure,α,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)-acetal contain two enone fragments, so they should have the potential to be attacked two times by binucleophilic species, which could result in the formation of six-membered ring systems. In addition, the variations of the substituents atα'-position and the alkylthio groups have the significant effect on their reactivity. Therefore, studies on the synthesis and the applications ofα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpen- tyl)-acetal should be a valuable research project.Developments of new basic reactions and new synthetic methods are the basis for the innovation and advance of organic chemistry. Based on the research achievement of our group inα?oxo ketene-(S,S)-acetal chemistry in the past fifteen years, my thesis starts from the synthesis ofα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)-acetal through synthetic design, aming to develop new basic reactions and new synthetic methods for interesting cyclic molecules, particularly, developing a new double [5 + 1] synthetic strategy to provide a general and simple route to polysubstituted six-membered ring systems. At the same time, starting from theα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)-acetals, investigations were also carried out on the synthetic methodology for five-membered nitrogen- and sulfur-containing heterocycles by intramolecular anti-Michael addition. In addition Synthesis of substituted indole N-Oxides, via Baylis-Hillman reaction ofα?Oxo cyclic ketene-S,S-acetal with o-Nitrobenzaldehydes and Subsequent Intramolecular Cyclization .The contents in this thesis mainly includes three parts and six aspects.In the first part, we utilizedα?Oxo cyclic ketene-S,S-acetal with o-Nitrobenzaldehydes and Subsequent Intramolecular Cyclization. They include:1. In the presence of TiCl4, the coupling reactions of alkylthio activated alkyl vinyl ketones with o-Nitrobenzaldehydes were first performed and a series of the polyfunctionalized 1,4-pentadienes compounds were obtained, afterward, the rearrangements reactions of these compounds catalyzed by base were completed and generated the corresponding polysubstituted indole N-Oxides compounds. The experiment revealed that the reactions proceed in a highly chemoselective and atom economical manner.In the second part of thesis, we focused on the intramolecular cyclization reactions ofα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)-acetal, and found two novel intramolecular double [5 + 1] addition reactions, resulting in the formation of three kinds of useful heterocycles including double six menbers of thiophen-3(2H)-ones and di4-pyridones, respectively.The contents in this part include:2. Development of a regioselective [5C + 1X] annulation strategy. We synthesized a series of Tetrahydrothiopyrano[2,3-b]thiopyran-4,5-diones via the one-step reaction betweenα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)-acetal and Na2S?9H2O . It is notable that the nontoxic and commercial available Na2S?9H2O was used as the sulfur source.3. Dimsyl anion mediated tandem fragmentation cyclization reactions of alkenoyl ketenedithioacetals, Synthesis of substituted 2, 3-dihydro-4H-thiopyran- 4-ones. And then synthesis of substituted tetrahydrothiopyrano[2, 3-b]thiopyran-4,5- diones.4. As the further application of double [5 + 1] annulation strategy, we realized the [5C + 1N] annulation betweenα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)- acetals and amines, developing a new method for the synthesis of tetrahydro-1,8- naphthyridine-4, 5(1H, 6H)-diones.In the third part of thesis, we found another case of intramolrcular anti-Michael addition toα,β--ethylenically-unsaturated enones, in which an intramolecular thio-anti-Michael additions ofα,α'-dialkenoyl ketene-(1, 3-dithiolancycolpentyl)- acetals could occurred in the presence of amines, allowing the formation of five-membered sulfur-containing heterocycles. It has shown once again the deactivation of carbonyl group of the enone systems is an efficient strategy for an anti-Michael addition.The contents in this part include:5. In the presence of EtOH we research the ring-opening reaction of its 1, 3-dithiolancycolpentyl moiety and gain multisubstituted 2, 3-dihydro-4-pyridones derivatives.In the presence of DMF we research the ring-opening reaction of its 1, 3-dithiolancycolpentyl moiety and gain multisubstituted thiophene derivatives.6. And then we choose different kinds of organic solvents found a solvent effect organic reaction and then can got hiophene derivatives or pyridones derivatives. It has shown that not only the deactivation of carbonyl group of the enone systems is an efficient strategy for an anti-Michael addition but also the solvent is a effection. Based on this result, our team carried out further research and found the spectra of such reaction is quite wide. Studies on this topic are under investigation in our laboratory.