Cobalt-Catalyzed Carbonylation of Benzyl Halides Using Polyethylene Glycols as Phase-Transfer Catalysts

Hydroxycarbonylation of benzyl and substituted benzyl chloride and bromide derivatives was achieved in good yields (up to 97.6%) and quantitative chemoselectivity, in the presence of Co<INF>2</INF>(CO)<INF>8</INF> as the transition metal and polyethylene glycols as the phase-transfer catalyst in an organic solvent/20% aqueous NaOH two-phase system under mild conditions (1 bar CO, room temperature). η¹-Benzyl-, η³-benzyl-, and (η¹-phenylacetyl)cobalt carbonyls were investigated as intermediates of this catalytic process.