1: With tris-(dibenzylideneacetone)dipalladium(0); hypophosphorous acid; 9,9-dimethyl-4,5-bis(diphenyl-phosphino)xanthene in N,N-dimethyl-formamide T=85°C; 12 h; 2: With oxygen in N,N-dimethyl-formamide T=110°C; 20 h; Further stages.;