The ability of cyclodextrin to interactwithmeta-trisulfonated triphenylphosphane deriva-tives bearing one or two methyl (or methoxy)groups on the aromatic ring has been investigatedby NMR and UV-vis spectroscopy. In the case ofnativeb-cyclodextrin (b-CD), the presence of onemethyl or methoxy group in theortho-position oneach aromatic ring is necessary to hamper the for-mation of an inclusion complex between theb-CDandmeta-trisulfonated triphenylphosphane deriva-tives. In the case of methylatedb-CD, the formationof an inclusion complex is only observed when themeta-trisulfonated triphenylphosphane contains amethyl group in thepara-position. The poor affinityof methylatedb-CD towards modified trisulfonatedtriphenylphosphanes was attributed to the sterichindrance generated by the methyl groups on theCD secondary face. The absence or presence of aninteraction between phosphanes and methylatedb-CD was also confirmed by catalytic experiments.Thus, the phosphanes that do not interact with themethylated CD were the most efficient mass-trans-fer promoters in an aqueous biphasic palladium-cat-alyzed Tsuji–Trost reaction.