NaH-mediated Selective Semihydrogenation Of Alkynes And Deprotection Of Sulfonamide

This thesis includes three sections:The first section described the chemoselective semihydrogenation of alkynes.The chemoselective semihydrogenation of alkynes is one of the most important reactions in organic chemistry.At present,there are many methods for the chemoselective semihydrogenation of alkynes by using H2 or transfer hydrogenating agents as hydrogen source.In this paper,NaH could be switched to a nucleophilic reductant with the addition of Pd or Rh metals as a promoter,the reactivity of which was engineered into chemoselective semihydrogenation of alkynes.In the second section,we described the desulfuryl protection of sulfuramide.The protection and deprotection of amine are important for the synthesis of biologically active nitrogen-containing compounds.Ts is one of the most versatile amine protecting groups.It is stable under many reaction conditions,and the sulfonamide-containing molecules are easily separated and purified by recrystallization.Moreover,its stability also makes the deprotection of sulfonamide difficult.This dissertation mainly focuses on a new method for deprotection of sulfonamide by the use of NaH.The method features simple operations,mild reaction conditions and good functional group tolerance.The third section described the synthesis of two positional isomers of heterocyclic compound 12H-chromeno[2,3-b]quinolin-12-one and 6H-chromeno[4,3-b]quinolin-6-one under high temperature with anthranil and 4-hydroxycoumarin as substrates.Compared with the route reported in the literature,this method is only a simple one-step reaction without the help of catalysts and additives.It is a new and environmentally friendly method.