Construction Of P-O Bonds And C=N Bonds By Electrochemically Enabled Cross Dehydrogenative Coupling

Cross Dehydrogenative Coupling(CDC)reaction has long been considered to be an ideal way to construct new chemical bonds,and it is one of the most atomic economic methods in organic synthesis.The advantages of this reaction have led to its continuous use in various synthetic studies.Although a large number of studies have promoted the rapid development of Cross Dehydrogenative Coupling reactions,there are still many shortcomings in the classical Cross Dehydrogenative Coupling work(such as the construction of P-O bonds,C=N bonds and other chemical bonds).Rare,noble metals and even the use of ligands lead to high cost of dehydrogenative cross-coupling reaction.The excessive use of oxidants can easily lead to over-oxidation of the reaction,and the formation of by-products can reduce the yield of target products,resulting in unsatisfactory experimental results.The use of a large number of additives,acid and base is not environmentally friendly.The electro-organic synthesis method using electron transfer to carry out redox on the electrode,which can effectively reduce or even replace the use of an oxidant or a metal catalyst.It is an ideal method to achieve cross-coupling of dehydrogenation.In this paper,we have mainly studied the method of efficiently constructing P-O bonds and C=N bonds under electrochemical conditions.In these reactions,we only use simple and easily available electrolytes and environme ntally friendly solvents to obtain energy-saving,simple and efficient synthesis methods.The specific research contents are as follows:(1)Organphosphorus compounds are widely used in organic synthesis,medicinal chemistry and material chemistry,and play an indispensable role.The development of new synthetic methods for these compounds has attracted more and more attention.We have developed a method for electrochemical dehydrogenative coupling to construct P-O bonds,which can synthesize various Phosphonates in high yield from P-H compounds and alcohols.This method has a series of advantages: mild reaction conditions,green environmental protection of all reagents,high atomic economy,good tolerance of functional groups,etc.We have also successfully achieved the gram-scale reaction and phosphine esterification of some simple natural products containing hydroxyl groups,and proved the feasibility of electrochemistry in practical synthesis and modification of natural products.(2)Tetrahydroisoquinoline derivatives are widely present in natural products,anti-cancer and anti-bacterial drugs,and their research is of great significance.We have developed a method for electrochemical dehydrogenative coupling to construct C=N bond.A series of tetrahydroisoquinoline nitrogen heterocyclic derivatives,such as benzimidazoles and quinazolinones,have been synthesized in excellent yields from intramolecular dehydrogenative coupling of tertiary amines and aromatic amines(amides).The method has the advantages of cheap raw materials,simple operation,mild reaction conditions and green environmental protection.We have successfully synthesized the natural products of deoeyvasicinone and rutae carpine,which provides an ideal strategy for the application of electrochemical dehydrogenative cross-coupling in the synthesis of natural products.