Water → [(7S,9Z,11S,12R,13S,14R,15R,16R,17S,18S,19Z,21Z)-2,15,17,29-tetrahydroxy-11-methoxy-3,7,12,14,16,18,22-heptamethyl-6,23,26,27-tetraoxo-8,30-dioxa-24-azatetracyclo[23.3.1.14,7.05,28]triaconta-1(28),2,4,9,19,21,25(29)-heptaen-13-yl] acetate

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Reaction Steps

A solution of 3.0 g of 3-bromorifamycin S in 50 ml of methanol and 70 ml of phosphate buffer of pH 8.0 (0.065 mole of Na2HPO4 and 0.004 mole of KH2PO4 per liter of water) is refluxed for 4 hours. The colour of the reaction solution changes during this time from blue-violet to yellow-brown. The reaction solution is then oxidised with excess potassium ferricyanide and, after acidification to pH ~3, is extracted with chloroform. After drying and concentration by evaporation of the chloroform extract, the residue is dissolved in ether and the ether solution is exhaustively extracted with phosphate buffer of pH=6. The wine-red aqueous buffer extract is acidified until the colour changes to yellow, and the precipitated 3-hydroxyrifamycin S is taken up with chloroform. After evaporating off the chloroform, 3-hydroxyrifamycin S is obtained in the form of a yellow foam, and the fact that it is identical with the fermentation product obtained earlier can be verified by thin-layer chromatography, 360-MHz-1H-NMR spectra, and by UV and IR spectra.

Provenance & Evidence