Exploring bisphenol-A derived bisphosphine ligands in Rh-catalysed hydroformylation of terminal alkenes

In this study, we report the synthesis and evaluation of three bisphosphine (L1–L3) and two monophosphine (L4, L5) ligands derived from a simple and cheap Bisphenol-A backbone for rhodium-catalysed hydroformylation of terminal alkenes in comparison with representative Xantphos and triphenylphosphine. All the ligands were characterised using NMR and HRMS analysis. Ligand L3 with a rigid fluorene backbone displayed better performance than the other ligands in the rhodium-catalysed hydroformylation of 1-octene, giving >99% conversion, 94% aldehyde selectivity with 74% linear selectivity and 566 turnover numbers. Scope extension with terminal alkenes varied with chain length and steric properties revealed the highest linear selectivity for 1-hexene (86%) and a deterioration in linear selectivity with the increase in alkyl chain length of the alkenes. 2,3-Dimethyl-2-butene and diisobutylene bearing a mixture of steric hindered terminal and internal alkenes showed poor conversions. Styrene showed the expected preference to branched aldehyde with 93% selectivity.