Copper Catalyzed 1,1-Difunctionalization Of Terminal Alkynes

As a structure widely presented in natural products and bioactive molecules,olefins have long attracted the attention of chemists.The difunctionalization of terminal alkynes is one of the important strategies to construct multisubstituted olefins.Most of the reported methods almost exclusively result in 1,2-difunctionalization regardless of the difference in the synthetic routes.In contrast,the reports on the 1,1-difunctionalization of terminal alkyne are scarce.Therefore,the development of a suitable method to accomplish 1,1-difunctionalization of terminal alkynes is an important complement to construct highly functionalized olefins.This dissertation is divided into four parts.The first part is a review of the functionalization reactions involving terminal alkynes.The latter three parts mainly explore the 1,1-difunctionalization of terminal alkynes.The following is a brief introduction to the dissertation:1.Copper-catalyzed geminal difunctionalization of terminal alkynes:a three-component reaction for the construction of vinyl sulfones.A three-component reaction of a terminal alkyne with ethyl diazoacetate and sulfonyl hydrazide is carried out to obtain multisubstituted alkenyl sulfone compound in the presence of copper(I)and base.This reaction has good regioselectivity and stereoselectivity,and provids a more convenient method for the synthesis of multisubstituted vinyl sulfones.2.Ligand-accelerated copper-catalyzed three component carboboration of terminal alkynes.A three-component reaction of the terminal alkyne with ethyl diazoacetate and bis(neopentyl glycolato)diboron is carried out to obtain a multisubstituted alkenyl boronates in the presence of copper(?),ligand and base.The copper catalyst participates in two catalytic cycles in this method,which is an important supplement to the development of a method for the construction of multisubstituted alkenyl boronates.3.Copper-catalyzed 1,1-difunctionalization of terminal alkynes by splitting sulfonyl hydrazones into two parts.This system is capable of reusing the diazo ester and the sulfonyl hydrazide anion which are generated in situ from the sulfonyl hydrazide,for the1,1-difunctionalization of terminal alkynes in the presence of copper(?)and base.This method is a good precedent for the development of atomic economic reactions involving sulfonyl hydrazide.For the above studies,based on the control experiments and GC-MS,NMR,HRMS,we proposed a mechanism involving carbene chemistry.The advantages including inexpensive starting materials and easy operation,will make these methods get more applications in the future.