 By extension , any <unk> cation regardless of its origin is capable of undergoing a <unk> <unk> . There have been a large number of examples published where the <unk> cation is arrived at by a variety of <unk> . One such example involves the silver <unk> <unk> ring opening of <unk> <unk> <unk> . The silver salt facilitates loss of chloride via precipitation of <unk> silver chloride . 
