Studies On The Synthesis And Applications Of α-Alkenoyl Ketene-(S,S)-Acetals

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 and Michael additions, as well as the synthetic applications based on the above reactions.Among the variousα-oxo ketene-(S,S)-acetals,α-alkenoyl ketene-(S,S)-acetals are easier to prepare and bear much more functionalities. From the view of structure,α-alkenoyl ketene-(S,S)-acetals 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-alkenoyl ketene-(S,S)-acetals 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 of newα-alkenoyl ketene-(S,S)-acetals through synthetic design, aming to develop new basic reactions and new synthetic methods for interesting cyclic molecules, particularly, developing a new [5 + 1] synthetic strategy to provide a general and simple route to polysubstituted six-membered ring systems. At the same time, starting from theα-alkenoyl ketene-(S,S)-acetals, investigations were also carried out on the synthetic methodology for five-membered oxygen-, nitrogen- and sulfur-containing heterocycles by intramolecular anti-Michael addition. The contents in this thesis mainly includes two parts and seven aspects.In the first part, we utilizedα-alkenoyl ketene-(S,S)-acetals as the 1,5-bielectronic...