Isomerization of electron-poor alkynes to the corresponding (E, E)-1,3-dienes using a bifunctional polymeric catalyst bearing triphenylphosphine and phenol groups

Abstract

The use of a bifunctional non-cross-linked polystyrene bearing both phosphine and phenol groups for the organocatalytic isomerization of alkynes bearing electron-withdrawing ester substituents to afford the corresponding (E,E)-dienes in excellent yield and stereoselectivity is described. When polystyrene functionalized with only phosphine groups was used as the catalyst, either low or no yield of the desired product was obtained. Thus both of the functional groups of the bifunctional polystyrene catalyst were essential for efficient catalysis to occur. This bifunctional polymeric catalyst was also used to synthesize (E,E,E)-trienes and (E,E)-diene-substituted 2(H)-pyran-2-ones from the corresponding alkynes. © Georg Thieme Verlag Stuttgart New York.