Study On Cbr₄ Promoted Heterocyclics Synthesis

This thesis depicts the author's graduate research works which have been focused on carbon tetrabromide mediated synthesis of heterocyclic compounds and Oxidative C-N Bond Formation and intramolecular aerobic oxidative deh ydrogenative arylation of aldehydes.It comprises three parts,the first part is t he literature review,introduces the recent research progress of synthesis metho ds of benzoxazole derivatives in recent years.The second part and the third p art deal with the author's own researches which are summarized as follows:(1)The carbon tetrabromide mediated oxidative carbon-nitrogen bond for mation of 2-aminopyridines or 2-aminopyrimidines with ?-keto esters or 1,3-di ones,leading to a variety of complex imidazo[1,2-?]pyridines or imidazo[1,2-?]pyrimidines,is repord.The reactions were realized under mide metal-free con ditions.(2)A simple and practical carbon tetrabromide promoted intramolecular a erobic oxidative dehydrogenative coupling reaction has been developed to prov ide a straightforward ring closure protocol for 2-aryloxybenzaldehydes to furni sh xanthones.The reaction was performed under metal-,additive-and solventfree conditions with good tolerance of functional groups.The present method is also applicable to the synthesis of fluorenones by using 2-arylbenzaldehydes as substrates.Preliminary studies of the reaction mechanism indicated that th e reaction may proceed through a radical pathway.