Studies On The [5+1] Annulation Reaction With α-Alkenoyl-α-Carbamoyl Ketene Dithioacetals As 1,5-Bielectronic Five-Carbon Components

Since Kelber first synthesized theα-benzoyl ketene-(S,S)-acetals in 1910,α-oxo ketene-(S,S)-acetal chemistry has become an important division in organic chemistry through the development of near one hundred years. Particular in recent decades, quite amount of reports 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 reactionsAmong 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 years, we developed a [5+1] synthetic strategy, in this dissertation, we utilizedα-alkenoyl-α-carbamoyl ketene dithioacetals as the substrates, investigation were carried out on this synthetic methodology for a deeper step, and a series of polysubstituted cyclohexenones, phenols, pyridones, thiopyranones and selenopyrancarboxamides with higher yields were synthesized under milder condition . The contents in this dissertation include three parts:1. Synthesis of polysubstitude phenols based on the [5+1] annulation reaction ofα-alkenoyl-α-carbamoyl ketene dithioacetals.2. We utilizedα-alkenoyl-α-carbamoyl ketene dithioacetals for the application of [5+1] annulation of other types, and developed this strategy to [5C+1Se], the experimental results proved their splendid activities again, which established the further applications in the organic synthesis.3. We utilizedα-alkenoyl-α-carbamonyl ketene dithioacetals as substrates to react with diethyl malonate which contain active methylene, and polysubstitude cyclohexenones were achieved, in the process of hydrolization of cyclohexenones, we did not gained the polysubstitude phenols to our expection, but the reaction went through a retro-Michael reaction, and the highly functionalized conjugated trienes were achieved, which had many reactive position and were important synthetic intermediate.