1: 4-(dihydroxyboryl)benzoic acid With N,N-diethanolaminomethyl polystyrene in tetrahydrofuran T=20°C; 1 h; 2: isopropylamine With benzotriazol-1-yloxyl-tris-(pyrrolidino)-phosphonium hexafluorophosphate; N-ethyl-N,N-diisopropylamine in N,N-dimethyl-formamide T=20°C; 20 h; 3: in tetrahydrofuran; water T=20°C; Further stages.;