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Crystal structure of 9-deoxo-9a-aza-9a-N-(p- bromobenzoyl)-8,9- didehydro-6-deoxy-6,9-epoxy- 9a-homoerythronolide A

Source of material: Erythromycin A 6, 9-imino ether is an intermediate in the synthesis of azithromycin. This synthesis is based on an acid catalysed cleavage of both sugars of erythromycin A 6, 9-imino ether followed by the condensation of aglycone with p- bromobenzoylchloride. Since in the refinement there were not observed any conformational differences between the three independent molecules in the super-structure, the structure was refined in the subcell a'=a/3, b'=b, c'=c, ß'=ß. The conformation of the aglycone ring is consistent with the analogous azalide derivatives except in the region of the 6, 9- epoxy plane (refs. 1 and 2). C28H40BrNO8, monoclinic, P21 (No. 4), a =10.647(6) Â, b=6.991(6) A, c =20.913(8) A, ß =109.24(3)°, V= 1469.7 A3, Z=2, R(F) =0.048, Rw(F) =0.048.

crystal structure ; 15-membered macrolide antibiotic ; derivatives

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