The addition of trichloromethyl compounds to olefins under iron or copper chloride catalysis is a general process, without almost any restriction on the olefin, and provides for high yields of 1: l adducts without te1omerization. l Trichloromethane phosphonyldichloride reacts in a similar fashion, via a redox chain. The phosphonylchloride function is retained in the adducts, as expected.