tris-(dibenzylideneacetone)dipalladium(0); hypophosphorous ether; 9,9-dimethyl-4,5-bis(diphenyl-phosphino)xanthene in N,N-dimethyl-formamide T=110°C; 17 h; Inert atmosphere;

phosphorus; potassium hydroxide; N-benzyl-N,N,N-trimethyl-ammonium chloride in 1,4-dioxane; water T=90 - 95°C; 3 h;

potassium hydroxide; hydrogen; anhydrous phosphine in water; dimethyl sulfoxide T=85 - 90°C; 2.5 h; Further byproducts.;