Construction Of Some Natural Product-like Compounds Via Tandem Reactions

Tandem reaction is one of the strategies employed in diversity-oriented synthesisdue to its atom economy and high efficiency. The method could generate smallmolecules with structural diversity and complexity. This thesis mainly focuses on theconstruction of some natural product-like compounds via tandem reactions.Firstly, based on the electrophilicity and [3+2] cyclization characteristics ofisoquinolin-2-ium-2-ylamide intermediates, a mild and efficien route toH-pyrazolo[5,1-a]isoquinolines via a C-H activation of alcohol is developed. Basedon the electrophilicity of isoquinoline N-oxides intermediates, a silver(I)-catalyzedtandem reaction of2-alkynylbenzaldoxime with phenol in the presence ofp-toluenesulfonyl chloride leads to1-aroxyisoquinolines in good yields.Secondly, using different trifluoromethanesulfanylation reagents can introducethe (trifluoromethyl)thio moiety into various scaffolds. A silver(I)-catalyzed reactionof2-alkynylbenzaldoxime with nucleophilic trifluoromethanesulfanylation reagent(AgSCF3) promoted by p-methoxybenzenesulfonyl chloride is described, whichgenerates the1-[(trifluoromethyl)thio]isoquinolines in good to excellent yields; Theincorporation of the (trifluoromethyl)thio group into the benzo[e][1,2]thiazine1,1-dioxide scaffold via a reaction of trifluoromethanesulfanylamide with2-(2-alkynyl)benzenesulfonamide is reported. The transformation proceeds undermild conditions to afford the4-((trifluoromethyl)thio)-2H-benzo[e][1,2]thiazine1,1-dioxides in moderate to good yields.Finally, a palladium-catalyzed tandem reaction of2-alkynylbromobenzene with2-(2-alkynyl)benzenesulfonamide is reported, which provides an efficient route forthe assembly of6H-benzo[f]indeno[1,2-d][1,2]thiazepine5,5-dioxides. A doubleinsertion of triple bonds is the key step during the transformation.