Conjugated Yne-enones Participated Additions, Cyclizations And Transformation Of The Products

Domino or tandem reactions have shown their unrivalled power in organic synthesis due to their high capability in merging several reactions into one operation. These reactions reduce the processing steps and the use of solvents, conforming to the morden demands of green chemistry.This dissertation mainly focuses on conjugated yne-enones, carried out a series of research, including the following parts.Firstly, we developed the phosphine-catalyzed additions of nucleophiles to conjugated yne-enones, which contains three aspects:hydrohalogenation reaction of terminal yne-enones to give3-halo-1,3-dienes; additions of weaker mucleophiles (such as acetic acid) to terminal yne-enones providing conjugating dienes and trienes; MePPh2-catalyzed additions of acetic acid to unterminal yne-enones leading to full-substituted dienes.Secondly, we studied an enantioselective cycloaddtion of yne-enones and1,3-dicarbonyl derivatives initially. The proccess, efficiently catalyzed by chiral thiourea-tertiary amine derivatives, serves as a powerful access to functionalized4H-pyrans upto85%ee. Further studies are in progress.Thirdly, we developed base-catalyzed diastereoselective tandem reactions of conjugated yne-enones with malonate-derived α,β-unsaturated esters or ketones and amino α,β-unsaturated esters, which provides a rapid, stereoselective access to multi-functionalized cyclopentanes and pyrrolidines.Forthly, a series of2-alkynyl carbonyl compounds containing a cyclopentane ring can be transformed into different fused dihydrobenzofurans and dienes, which deponds on the catalyst and the reaction time. We realized a cationic gold(Ⅰ)-catalyzed tandem reaction of highly funtionalized cyclopetenes and pyrrolidines, which contains highly stereospecific heterocyclization/1,2-alkyl migration to give [2,3-c]furans. Furthermore, we found that employing the same substrates can provide different products along different rearrangement. The regioselectivity of Au-catalyzed1,2-versus1,2’-alkyl migration is starting material and counterion-dependent. In the end, we described a novel Pd(OAc)2/CuI-cocatalyzed three-component reaction of yne-enones, nucleophiles and diaryliodonium salts to synthesize3-aryl tetrasubstituted furans in one step. Then we developed an efficient method for the synthesis of tetrasubstitued allene ketones from the same starting materials under different conditions.