New Methods For Synthesis Of N-Heterocycles Based On Vinylene Carbonate

N-Heterocyclic compounds not only widely exist in plants and animals,but also involve in the development of materials science and fine chemicals.Therefore,the synthesis of N-heterocyclic compounds has attracted the attention of organic workers.In recent years,the strategy of metal-catalyzed C-H functionalization have been widely used to construct various nitrogen heterocyclic frameworks.Although this strategy has high atom economy and step economy,the types of synthons involved in the reaction are still limited.Therefore,searching for new and efficient synthons has become the focus of research.Recently,vinylene carbonate has been reported as an ideal surrogate for acetylene,which can successfully participate in cyclization under metal catalysis,showing a potential synthetic application prospect.This dissertation mainly focuses on the strategy of metal-catalyzed cyclization of vinylene carbonate as C2 synthon to explore the construction of more important Nheterocyclic compounds.The main research work is as follows:(1)The rhodium-catalyzed[4+2]annulation of vinylene carbonate and Narylimine was achieved,and the reaction was further simplified to[3+2+1]annulation involving arylamine,arylaldehyde and vinylene carbonate.Through the screening of catalyst,solvent and reaction feed ratios,the most suitable reaction conditions were determined,and the applicability of N-arylimine,aromatic amine and aromatic aldehyde substrates were investigated under the optimal conditions.Substituents with different electronic effects are well compatible,and finally 42 cases of 2-arylquinolines with diverse structures were obtained.Derivatization experiments show that functionalized active biomolecules are also well compatible with this reaction,and the products can be used to prepare potential photocatalysts.Mechanism exploration experiments show that the reaction undergoes ligand exchange,olefin insertion,β-oxygen elimination and other processes.This work uses imine as a directing group to continuously realize the activation of two C-H bonds,and expands the efficient synthesis of C3,C4-unsubstituted 2-arylquinoline compounds with vinylene carbonate as a C2 synthon.(2)The ruthenium-catalyzed[4+2]cyclization of vinylene carbonate and 2arylquinazolinones was achieved.The optimal reaction conditions were determined by systematic screening of solvent,catalyst,temperature and time.The substrate applicability of 2-arylquinazolinones was investigated under the optimal conditions,and the results showed that the substrates with different electronic and steric effect substituents were well compatible.A total of 28 structurally diverse 2,3-fused quinazolinone derivatives were obtained in good to excellent yields(54%-86%).The catalytic system can be applied to the activation of C(sp2)-H bonds in nitrogen heterocycles,oxygen heterocycles,and sulfur heterocycles.Mechanism exploration experiments show that the reaction undergoes successively directed intramolecular C-H bond activation,alkene insertion,and β-oxygen elimination.In this work,the continuous construction of C-C bonds and C-N bonds was realized by a one-pot method under the catalysis of inexpensive metal ruthenium,and vinylene carbonate was used as a C2 synthon to participate in the C5,C6-position unsubstituted 2,3Construction of fused quinazolinone skeletons.(3)The yttrium-catalyzed[3+2]annulation of vinylene carbonate and aniline derivatives was achieved.Through the screening of catalyst,ligand,reaction solvents,additives,temperature and time,the optimal reaction conditions were determined,and the applicability of aniline derivatives was investigated under the optimal reaction conditions.It has a wide range of chemical compatibility and shows good tolerance to the highly specific groups such as-NO2,-CN,-TMS andMS,finally obtained 82 cases of C2,C3-unsubstituted indoles with diverse structures.The derivatization experiments showed that the modified substrates containing seven active molecules,including estrone,aminolutamide,α-tocopherol,benzocaine,DL-menthol,bomeol and fructose diacetone,were successfully compatible.It is worth noting that this work is the first case to use inexpensive Y(OTf)3 as a catalyst to realize the construction of C2,C3-unsubstituted indole skeleton using vinylene carbonate as a C2 synthon.