Rhodium-catalyzed hydroformylation of 1,1-bis(p-fluorophenyl)ethene and 3,3-bis(p-fluorophenyl)propene

1,1-Bis(p-fluorophenyl)ethene and 3,3-bis(p-fluorophenyl)propene were hydroformylated using rhodium catalysts: whereas, the chemoselectivity of the reaction is rather high fbr both olefins, the regioselectivity towards the formation of the linear aldehyde is very high only for the former substrate. In the case of the latter olefin extensive double bond isomerization takes place under oxo conditions. The obtained 3,3-bis(p-fluorophenyl)propanal is converted to 4,4-bis(p-fluorophenyl) butanal by an improved two-step homologation procedure involving a Wittig reaction. This aldehyde is a valuable building block for some interesting pharmaceuticals. (C) 1999 Elsevier Science B.V. All rights reserved.