Highly efficient catalyst system for the synthesis of 2‐arylpropionic acids by carbonylation

Carbonylation of 1‐(4‐isobutylphenyl)ethanol has been studied using a homogeneous catalyst system consisting of PdCl₂(PPh₃)₂/ TsOH/ LiCl. Higher reaction rates with TOF up to 1200 h⁻¹ and ibuprofen selectivity >95% have been achieved at 388 K under a CO partial pressure of 5.4 MPa. The reaction proceeds through the formation of 4‐isobutylstyrene and 1‐(4‐isobutylphenyl)ethyl chloride as intermediates. The same catalyst system is shown to be effective for carbonylation of various α-arylethanols, vinyl aromatics and corresponding chloro derivatives. This revised version was published online in July 2006 with corrections to the Cover Date.