18 631 R.P. 18631 RP 1H-Pyrrole-2-carboxylic acid, 5-methyl-, 3'-ester with N-(8-chloro-7-((6-deoxy-5-C-methyl-4-O-methyl-alpha-L-lyxo-hexopyranosyl)oxy)-4-hydroxy-2-oxo-2H-1-benzopyran-3-yl)-4-hydroxy-3-(3-methyl-2-butenyl)benzamide 39868-96-7 Antibiotic RP 18,631 Chlorobiocin Clorobiocin NSC 227186 RP 18631