Construction Of Important Nitrogen-containing Molecules Based On Mild Conversion Of Carbodiimide

Carbodiimide,as a heterocumulene molecule with unique chemical properties,has become an important precursor for the construction of nitrogen-containing compounds and has significant application value in the medicinal development and biosynthesis field.Traditional chemical conversions of carbodiimide mostly require transition-metal catalysis or relatively harsh reaction conditions,such as high temperature,high pressure and strict anhydrous and anaerobic environment,and also some of the reaction show relatively poor substrates universality.Therefore,developing rapid conversion methods with mild reaction conditions,transition-metal free,and a wide range of substrate universality has been one of the hotspots for chemists exploring the synthesis of organic nitrogen molecules in recent years.In this paper,most of traditional carbodiimide involved reactions of carbodiimide in recent years are summarized.Three new conversion strategies of carbodiimide under mild reaction conditions are explored,where important nitrogen-containing compounds are synthesized.This paper mainly includes the following four parts:1.The recent studies on carbodiimide are classified and summarized,where the transition metal-catalyzed,organometallic reagents promoted,and transition-metal free involved carbodiimide reactions are introduced in detail.2.Study the inorganic base promoted synthesis of 5-amino-1,2,3-triazole derivatives employing carbodiimide and diazo compounds as substrates.The reaction does not require expensive transition metal catalysts and can be carried out readily under mild reaction conditions.The reaction mechanism was studied by control experiments and DFT calculation.The experimental results indicate that the reaction involves a selective nucleophilic addition/cyclization process.Further derivatization experiments of the product show that the reaction has a good application prospect.3.This section study a synthesis method of azaguanine derivatives with simpler reaction process under mild reaction conditions.Ethyl diazoacetate(EDA)and two same or different carbodiimides were used as substrate to prepare a variety of substituted azaguanine derivatives through a cascade cyclization process with good regioselectivity and reaction yields.The gram level reaction experiment indicates that this method has significant potential for large-scale application.4.This section explores the reaction promoted by ceric ammonium nitrate(CAN)for the preparation of o-nitroaryl urea employing carbodiimide as substrate.The method achieves the synthesis of two functional groups by one step with a wide range of substrate universality.A series of control experiments show that the reaction process involves a concerted nitration/ureation process enabled by CAN,and is distinctive from the conventional electrophilic nitrification.Control experiments show that the oxygen atom in urea group originates from nitrate ion in CAN.Subsequent derivatization experiments demonstrate that the reaction has a good application prospect.