mecarphon 3,7-Dimethyl-6-oxo-3-thioxo-2-oxa-4-thia-7-aza-3-phospha(V)octan-8-oic acid methyl ester MC-2420 7-Oxa-5-thia-2-aza-6-phosphaoctanoic acid, 2,6-dimethyl-3-oxo-, methyl ester, 6-sulfide AI 3-27723 AI327723 Mercarphon