l, C6-C20-aryloxy, C7-C40-arylalkyl, C7-C40-haloarylalkyl, C7-C40-alkylaryl, C7-C40-haloalkylaryl and OSiR3 3; and n is an integer from 1 to 10, to obtain a reaction mixture comprising at least one compound of formula A, and ii) bringing the reaction mixture into contact with at least one metallocene compound and optionally a support. 14.