Construction Of Heterocyclic Compounds Via Domino Reactions Of Sulfur-containing Enamino Esters

Heterocyclic chemistry is an important field of modern organic chemistry.Heterocyclic compounds have a wide range of applications in biochemistry,medicinal chemistry,and applied chemistry.In recent years,?-enamino esters have been widely used as an important synthetic regents for construction of various nitrogen-containing heterocycles,and is a very important synthone in organic synthetic chemistry.A literature survey showed that many elegant synthetic methods have been developed for the synthesis of heterocyclic compounds by using ?-enamino esters as key reagents.However,the new chemical reactions involving heteroatom-containing ?-enamine esters need further expanding.In this paper,the synthetic applications of sulfur-containing enamino esters for construction of nitrogen-containing heterocyclic compounds was successfully studied.A series of potentially biologically active N,O,S-conatining heterocyclic compounds were efficiently synthesized,which including benzo[b]pyrrolo[1,2-d][1,4]thiazine derivatives,pyrrolidine derivatives,pentacyclic indeno[1,2-b]phenothiazine derivatives,pentacyclic indeno[2,1-c]phenothiazine derivatives and fused rings Phenothiazine derivatives.1.In the presence of aceic acid,the domino cyclization reactions of sulfur-containing enamino ester and 1-aryl-2-nitroethylene or nitrochromenes was studied.The reaction proceeded with Michael addition,annulation and aromatization process to give interesting benzo[b]pyro[1,2-d][1,4]thiazine and dihydrobenzo[b]chromeno[4',3':4,5]pyrro[1,2-d][1,4]thiazine derivatives.This reaction has the advantages of simple reaction conditions and high reaction yield.The structures of the twenty-three synthesized compounds were characterized by IR,NMR,HRMS,etc.and five single crystal structurs were measured by X-ray diffraction method.2.The domino cycloaddition reactions of sulfur-containing enamino esters with aromatic aldehydes and cyclic)?-diketones(1,3-indandione,1,3-cyclohexanedione,5,5-dimethylcyclohexanedione,1,3-cyclopentanedione)were studied in the presence of acetic acid as caalyst.The concentration of acetic acid plays a crucial role in the cycloaddition reaction.The isomeric phenothiazine derivatives were selectively ormed in the different concentrations of acetic acid via high regioselectivity.These reactions successfully gave a total of 11 unreported pentacyclic tetrahydroindeno[1,2-b]phenothiazines,five pentacyclic dihydroindeno[1,2-b]phenothiazines,seven pentacyclic dihydroindeno[2,1-c]phenothiazines,nine 2,3,4,7-tetrahydrobenzo[c]phenothiazine-6-carboxylates,fifteen 7,9,10,12-tetrahydrobenzo[b]phenothiazine-11-carboxylates,two 1,2,3,3a,4,10-hexahydrocyclopenta[b]phenothiazine-11-carboxylates,and six 1,2,3,10-tetrahydrocyclopenta[b]phenothiazine-11-carboxylates.The structures of these compounds were characterized by IR,NMR,HRMS,etc.,and seven single crystal structures were determined.3.The tandem reaction of sulfur-containing enamino esters with aromatic aldehydes or a-diketone compounds(acenaphthoquinone,ninhydrin and benzoylformaldehyde)catalyzed by acetic acid was studied.The reaction of sulfur-containing enamino esters with aromatic aldehydes via a four-component reaction,which demonstrating the diverse reactivity of ?-enamino esters.A total of 21 unreported fused phenothiazine derivatives and 8 pyrrole fused polycyclic derivatives were synthesized by domino cycloaddition reaction.The structures of the synthesized compounds were characterized by IR,NMR,HRMS,etc.,and the six single crystal structures were measured.