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

α-Oxo ketenedithioacetals are a kind of versatile intermediates in organic synthesis. Since Kelber first synthesized in 1910,α-oxo ketene-(S,S)-acetals chemistry has become a hot spot in organic chemistry research through the development of about one hundred years. It can be used in many reactions for their functional group multiplicity and special stereoelectronic effect from the alkylthio functionalities, react not only with electrophilic reagent but also with nucleophilic reagent. It can construct many compounds with special structures and can be applied in organic synthesis and the composition of natural products.α-Hydroxy ketene-(S,S)-acetals, synthesized byα-oxo ketenedithioacetals which is reducted, is easier to prepare and bear much more functionalities. From the view of structure,α-hydroxy ketene-(S,S)-acetals belong to allylic alcohol. Because of receiving the affection of strong supplies electron from the alkylthio functionalities,α-hydroxy ketene-(S,S)-acetals form stable carbon cation easily atαposition and carry on nucleophilic substitution reaction with nucleophilic reagent. In addition, received the affection of changes from functionalities atα′position and alkylthio functionalities, the nature ofα-hydroxy ketene-(S,S)-acetals also change remarkably. Therefore, studies on the synthesis and the applications ofα-hydroxy ketene-(S,S)-acetals should be a valuable research project.Based on the research achievements of our group inα-oxo ketene-(S,S)-acetal chemistry in the past several years, my thesis under synthetic design, taking the synthesis of newα-hydroxy ketene-(S,S)-acetals as foundation, explores a series of basic reactions whichα-hydroxy ketene-(S,S)-acetals can react, such as Ritter reaction,C-C bond-forming reaction,Dehydration reaction and Etherification reaction, and based on these basic reactions, we also carried out on the new synthetic methodologies for oxygen-, nitrogen-containing heterocycles. The contents in this thesis mainly include four aspects:1. Design and synthesisα-Oxo ketenedithioacetals, prepared a series ofα-hydroxy ketene-(S,S)-acetals by reduction.2. Study a series of basic reactions whichα-hydroxy ketene-(S,S)-acetals can react, including Ritter reaction with acetonitrile,C-C bond-forming reaction with active methylene compounds and activated alkenes,Dehydration reaction and Etherification reaction with alcohol.3. Base on C-C bond-forming reaction with active methylene compounds, used coupling products—polycarbonyl compounds to synthesis 3,4-dihydropyridin-2(1H)-ones.4. Study one-step intramolecular ring-closure reaction ofα-alkenoyl ketene-(S,S)-acetals by reduction and synthesis type ofδ-lactones compounds.