Research On Cross-dehydrogenative-coupling Reaction Of Methyl Ketone And Dimethylsulfoxide

The development of novel synthetic ways to construct C-C bonds is an important research direction in organic chemistry.Exploring new reactions of C-C bonds formation can improve synthesis efficiency,and promote the development of organic synthetic chemistry.Cross-dehydrogenative-coupling?CDC?reactions,which coupling of two C-H bonds has the potential to construct new C-C bonds.This kind of coupling avoids the preparation of functional groups and thus makes synthetic schemes shorter and more efficient.CDC chemistry provid waste-minimized synthetic alternative to classic coupling and has become a promising method to make important contributions to green synthetic chemistry.In this paper,we put some efforts on researching new CDC reactions.The main contents are as follows:1.A K₂S₂O₈-mediated CDC reaction of methyl ketone and dimeth yl sulfoxide to construct C=C bond using dimethyl sulfoxide as one-carbon source is achieved under transition metal-free reaction condition.Various aryl ketone derivatives react readily with DMSO,producing the?,?-unsaturated carbonyl compounds in yields of 42 to90%.This method features a transition metal-free reaction condition,wide substrate scope and using DMSO as novel one-carbon source to form C=C bond.Based on the preliminary experiments,a plausible mechanism of this transformation is disclosed.2.A multiple sp³ C-H bonds coupling of the methyl group in methyl ketones with dimethyl sulfoxides is developed.This coupling allows the direct sp³ C-H bond coupling among three methyl groups and affords one C-C bond and one C=C bond under the transition metal-free condition.A variety of?-methylthio isopropenylketones were produced in moderate to high yields.This coupling of methyl groups could be applied to prepare 3-methylthiomethyl-chroman-4-ones under the reaction conditions.On the basis of control experiments,a plausible reaction path including successive C-H/C-H cross coupling,demethylthioation and C-H/C-H cross coupling is proposed.3.A systematic study for methyl ketone coupling wi th DMSO to construct furan ring is explored.In this transformation,dimethyl sulfoxide function as a dual synthon via sp³ C-H functionalization with two C-C bonds,one C-O bond and one C-S bonds formation in a one-step process.Promoted by the crucial iodine species,a number of ketones could be easily converted to 2,4,5-trisubstituted furans,which provide an extremely simple and expeditious approach to high value-added,biologically significant O-heterocycles.Based on the preliminary experiments,a plau sible mechanism is proposed.4.A Cu-catalyzed CDC reaction of methyl ketone,aniline and dimethyl sulfoxide to construct quinoline structure is developed.After screening of various conditions,such as base,oxidant,temperature,the optimal reaction condition is determined.In addition,a series of 2-arylquinoline compounds is synthesized using the optimal reaction conditions.On the basis of mechanism experimental evidence as well as previous related reports,a plausible reaction mechanism is proposed.