The Pd-catalysed hydromethoxycarbonylation of aliphatic internal alkenes with minimal double bond isomerisation

The methoxycarbonylation of internal alkenes by a palladium(II)complex comprising PdCl₂, bis(2-methoxyphenyl)phenylphosphine (2) and HCl has been investigated. The results presented herein demonstrate a non-isomerizing Pd-complex for the effective production of internal esters from the corresponding internal aliphatic alkenes. Selectivities of >70% were obtained for the desired internal esters with no signs of catalyst decomposition. The high selectivity for the internal esters is rationalized on the basis of the hemi-lability of the o-methoxy moiety which may assist in ligand dissociation. To the best of our knowledge this is one of the first reported hydromethoxycarbonylation routes to internal esters from their corresponding internal aliphatic alkenes.