Two Conversion Reactions Of ?-substituted Allenoates Catalyzed By Phosphine

Phosphine catalysis of allenoates has been the hot field of organic synthesis in recent years.Because of the electron deficiency of the carbon in the center of the allenes,it is easy to be attacked by phosphine to afford zwitterion intermediates,leading to the formation of carbanion in the ? or ? position,which exist as resonance.In this regard,diverse adducts will be formed when they react with the substrates.Phosphine-catalysis of allenoate has been developed as an important strategy for the construction of multi-substituted functional groups of carboncyclic or heterocyclic compounds.As a typical class of disubstituted allenoates,?-substituted allenoates are important raw materials for organic synthesis,and widely used in the the synthesis of many biologically active compounds and pharmaceuticals' intermediates.In recent years,the phosphine catalyzed cycloaddition of allenoate has been developed rapidly,especially the [3+2] annulation reaction.In this context,the phosphine-catalyzed two-component reaction of allenoates and acrylate was studied to provide chiral trisubstituted allenes.In addition,the cycloaddition reaction of allenoates with carbon disulfide catalyzed by phosphine was studied,to synthesize thiophene derivatives.It is notable that an important intermediate in the treatment of glaucoma(MK0507)could be prepared through this method.In the first chapter,the progress of phosphine-catalyzed reactions of allenoates in recent years is reviewed from two aspects: cycloaddition reactions and non-cyclic reactions.In the second chapter,some studies on synthesis of chiral allenes in recent years are introduced.The two-component reactions of ?-substituted allenoates and acrylate in the presence of chiral phosphine was invesgated,and the product was separated and its structure was determined to be chiral trisubstituted allenes.The effects of different solvents,catalysts,temperature and the absence of benzoic acid in the reaction were investigated.The suitable range of substrates for allenoates was screened.Medium yields and high ee values were obtained under mild conditions.A phosphine-catalyzed new method was developed for the synthesis of chiral tri-substituted allenes from ?-substituted allenoates and acrylates.In third chapter,the reaction of ?-substituted allenoates with carbon disulfide catalyzed by phosphine was studied.The product was separated and its structure was determined to be thiophene derivatives.The effect of different catalysts on the reaction was investigated,and the suitable range of the substrate for allenoates was screened.Medium to good yields were obtained under mild conditions.The transformation of the prosucts were demonstrated and the reaction mechanism for the formation of thiophene derivatives was proposed.