Studies On Pyridylureas And Cyclic Ureas By The Selenium-catalyzed Carbonylation

The oxidative-reductive carbonylation of nitrobenzenes with anilines by one pot can lead to the formation of ureas with CO/Se as a catalytic system.The dissertation is tried to develop its application and is discussed about the method of synthesizing unsymmetric ureas with complexly substituted groups by employing this catalytic system.The results are proved to be feasible.The carbonylation of heterocyclic amines and nitro compounds and the cyclic carbonylation of compounds with double functional groups have been studied systematically and respectively,and the methods of synthesizing a series of unsymmetrically substituted ureas and benzimidazolone derivatives have been acquired. The selenium-catalyzed carbonylation of various nitro compounds with aminopyridines as coreagents is studied.It is found that aliphatic nitro compounds can抰 react with aminopyridines in the scope of our experiments and the carbonylation of aromatic nitro compounds with aminopyridines is well performed with a new result different from the literatures.Although aminopyridines are primary amines,achieved mixture aren抰 composed of three ureas of almost equal proportion including symmetric dipyridylureas,just giving priority to unsymmetrical ureas.The yield of the products is from middle to fine. The selenium-catalyzed cyclic carbonylation of a -nitro anilines with different substituted groups can be well conducted and a series of cyclic ureas---benzinudazo ABSTRACT LII lone and its derivatives, are formed in the process.The selectivity is excellent and the yield is high. The selenium-catalyzed carbonylation mechanism of nitro compounds andlor amines which are put forward in the literatures is summarized and some shortcomings are pointed out.The reaction of symmetric ureas substituted by amines is considered as a necessary part of the carbonylation process for the first time and this selenium-catalyzed carbonylation mechanism is initially discussed.