Studies On The Oxidative Demethylation Reaction And Oxidation Of The Sulfur Atom Of α-Acetyl Ketenedithioacetals

Advocacy and practice of green chemistry is essential to achieve sustainable development. Utilizing green chemical reagent is one important way to achieve such a goal.The catalytic system of copper salt and molecular oxygen, using molecular oxygen as the green oxidant, exhibits excellent regioselectivity and stereoselectivity in organic reactions. In recent years, copper/oxygenoxidative system has been widely used in the C–H bond activation and the construction of carbon–carbon/heteroatom bond.In addition, hypervalent iodine compounds are widely used in organic synthesis for its availability, low toxicity and mild reaction conditions etc.In recent years, the selective oxidation of sulfides using hypervalent iodine compounds has been rapidly developed.Ketene dithioacetals, which bearing multiple reaction sites, is a kind of versatile intermediatesin organic synthesis. In recent years, the study of ketene dithioacetals has been rapidly developed. Our group has long been engaged in the research of ketene dithioacetal chemistry in terms of α-functionalization reaction, Vilsmeier reaction, and their utilization in the construction of carbo-/hetero-cyclic compounds etc. Although a series of achievements have been obtained, the researches on the oxidative demethylation of α-acetyl ketene dithioacetals and the oxidation of the sulfur atom of ketene dithioacetals are still limited.This thesis is based on our previous works, and describes the oxidative demethylation of α-acetyl ketene dithioacetals and the oxidation of the sulfur atom of ketene dithioacetals. The thesis includes the following two parts:(1) the oxidative demethylation of α- alkenoyl-α-acetyl ketene dithioacetals was investigated using copper/oxygen catalytic system,α-alkenoyl-α-formyl ketene dithioacetals were obtained in high to moderate yield which could not be synthesized from common synthetic methods.(2)theoxidation of the sulfur atom of α,α-diacetyl ketene dithioacetals was investigated using PIFA/H2 O oxidation system,a series of sulfoxides were obtained in high yields. This synthetic method has the merits such as simple operation, high reaction speed and in high yields.In this thesis, totally eleven α-alkenoyl-α-formyl ketenedithioacetals and twenty-five sulfoxides were newly synthesized. The products have been characterized by 1H–NMR, 13C–NMR, HRMS, single crystal diffraction analysis.