Study On Selective Transformation Of Alkynes And Construction Of Aromatic Ring

Aromatics are important organic compounds, some of them either isolated fromnature or prepared by chemical reaction show interesting physiological andbiological activity, which have high potentiality for the application as medicinalmolecules or starting materials for the synthesis of medicines, besides, highlyconjugated aromatic compounds have been recent employed as organicphotovoltaics. In addition, alkynes are important synthons in organic synthesis, andthey can be used in synthesis of various cyclic coumpounds by cycloaddition andcondensation reactions. Therefore, development of the efficient methods for thesynthesis of aromatics by alkynes is one of the most important research topics inorganic chemistry.The cyclocondensation of alkynes is one of the efficient synthetic methods forthe construction of aromatics, thus in this dissertation, a formal [3+3]cyclocondensation strategy for the synthesis of polysubstituted phenols by thereaction of alkynyl ketones with1,3-dicarbonyl compounds was developed.Although the cyclocondensation usually afforded two or three phenol derivativesdepending greatly on the structures of starting materials, the considerable advantagesinvolving easy availability of starting materials, wide scope of reaction, as well aseasy separation of products make the present procedure a practical protocol forpolysubstituted phenols.Benzo[k]tetraphenes are potential organic photovoltaics, and1,4-cis,cis-distyrylbenzene and its derivatives were designed as the precursor for thesynthesis of them via oxidative dehydrogenative coupling of C-H bonds. In order tosynthesis of1,4-cis, cis-distyrylbenzene by semihydrogenation of the correspondingalkyne, a new Ru3(CO)12-catalyzed transfer semihydrogenation of diaryl alkynesusing DMF/H2O as hydrogen source affording cis-stilbenes was developed.However, the oxidative dehydrogenative coupling of C-H bonds in1,4-cis,cis-distyrylbenzene was not successful in the preliminary work, and further research work remains to be done. In addition, in the course of investigation ofsemihydrogenation of diaryl alkynes, it was found that1-(2-acetylphenyl)-2-phenylacetylene underwent the cyclodimerization to afford chrysene derivatives.The cycloisomerization of4-yn-1-ones is one of the efficient synthetic methodsfor the construction of polysubstituted furans. All the reported works mainly focusedon the addition of alkynes with terminal α,β-unsaturated enones affording4-yn-1-ones, and there were no reports on synthesis of polysubstituted furans byatom economic cycloaddition reaction of alkynes with α,β-unsaturated enones in onepot. Therefore, an In(OTf)3-catalyzed addition/cycloaddtion of alkyne with internalα,β-unsaturated enone affording4-yn-1-ones or polysubstituted furans was alsostudied in this dissertation.