Facile Access to Key Reactive Intermediates in the Pd/PR3-Catalyzed Telomerization of 1,3-Butadiene

Abstract

The Pd-catalyzed telomerization of 1,3-dienes is an important atom-efficient transformation, which effectively adds nucleophiles (NuH, for example, H2O, MeOH, NH3) over two C C coupled dienes in a 1,6- or 3,6-fashion (see Scheme 1).[1] As such, telomerization provides an economically attractive route for the production of C8 bulk chemicals, such as 1- octanol[2] and 1-octene.[3] Pd-catalyzed telomerization is also increasingly explored as a potential route for the valorization of biomass-derived feedstock.[1a] Although the catalytic cycle (Scheme 1) is generally regarded as well understood, only a limited number of studies have been reported that involve the preparation of reactive intermediates.[4–6] Clearly cumbersome preparative methods and the poor stability of [Pd(1,2,3,8-h4-octadien-1,8-diyl)- (PR3)] (B) are limiting further study. As a result the preparation of reactive intermediates derived from commercially relevant ligands (e.g. TPPTS; TPPTS=3,3’,3’’-phosphinidynetris( benzenesulfonic acid) trisodium salt) remains elusive.[7] B mainly acts as a base on NuH during catalysis and is readily converted into [Pd(1,2,3,7,8-h5-octa-2,7-dien-1- yl)(PR3)]+ (C)[4–5] and its derivatives. Both from a synthetic and catalytic point of view, C is the key intermediate as it lies at the focal point of the catalytic cycle and leads via several mechanistic pathways to species such as D, E, and F.