Research On The Reaction Between Carboxyl-oriented Carbon-hydrogen Bonds And Polar Carbon-carbon Double Bonds

The construction of carbon-carbon bond is one of the important research fields in organic synthesis.The traditional coupling reaction makes it possible to construct complex molecules,especially drug molecules and electronic materials.However,these methods have some disadvantages such as the requirement of prefunctionzaliz-ation substrates,low atom economy,by-products and environmental pollution.Therefore,it is highly desirable to develope efficient approaches for synthesizing organic compounds from readily available starting marerials.Transition-metal-catalyzed C-H functionalization has emerged as an efficient protocol to construct C-C bonds and C-heteroatom bonds.These transformations don't need pre-functionalization starting materials,thus shorten the synthetic step greatly,improve the atomic utilization and reduce environmental pollution.In order to improve the site-selectivity,the directing group are introduced in the substrates,which providing a novel method for the synthesis of natural products and industry.Carboxyl has been regarded as a promising directing group due to its advantages of existing widely in natural and drugs molecules,commercially available,stability,easy to store and and simple to handle.In addition,it can be easily removed via the decarboxylation or transformed to other functional groups.This thesis mainly focuses on the following aspects:Intermolecular tandem C-H olefination/cyclization has been achieved via a rhodium(?)-catalyzed C-H activation of carboxylic acids with acrylates.This method employs[Cp*RhCl2]2 as catalyst,Ag2CO3 as oxidant,Cu2O as additive,and is characterized by exclusive stereoselectivity,commercially available substrates,mild atmospheric conditions,and short reaction time(less than 2 h).A simple ruthenium-catalyzed conjugate addition of C-H bonds to ?,?-unsatura-ted ketones directed by a removable carboxyl group was developed to synthesize ortho-alkylated benzoic acids in a greener manner.Noteworthy features of this method include in neat water,without any additives,simple operations,and broad substrate scope.Meantime,the versatility and utility of the addition products were demonstrated through further transformation into commonly inaccessible but highly useful motifs of meta-substituted alkylbenzenes and 3-substituted isochromanones.