Synthesis and application of tetraphosphane ligands in rhodium-catalyzed hydroformylation of terminal olefins: high regioselectivity at high temperature.

A new class of substituted tetraphosphane ligands has been developed and applied in the rhodium-catalyzed regioselective hydroformylation of terminal olefins. The high regioselectivity (linear selectivity is above 97 % for 1-octene and 1-hexene) at high temperature (140 degrees C) shown by these tetraphosphane ligands is remarkable considering the low regioselectivity commonly observed under similar reaction conditions when other bisphosphane analogues are used. The steric and electronic effects of substituents on the diarylphosphane moiety have also been examined.