In search of new types of semisynthetic derivatives of the natural antibiotic rifamycin S (1), we synthesized 25‐O‐deacetyl‐27,28‐didehydro‐27‐demethoxy‐11‐deoxo‐11,29‐epoxy‐28, 29‐dihydro‐21,23‐O‐isopropyli‐denerifamycin S (3). Its X‐ray crystal structure shows a new type of ansa‐chain with an 11,29‐epoxy moiety, the loss of the MeO group on C(27), and the shift of the CC bond from C(28),C(29) to C(27),C(28). These modifications result in a conformational rearrangement of the whole ansa‐chain, nonetheless the overall spatial shape of the molecule is still close to that of most rifamycins. As found in other 11‐deoxo‐11‐hydroxyrifamycin‐S derivatives, the chromophore rings of 3 give rise to π‐π association in the crystal.
X-ray crystal structure of 25-O-deacetyl-27,28-didehydro-27-demethoxy-11-deoxo-11,29-epoxy-28,29- dihydro-21,23-O-isopropylidenerifamycin S / C., Bartolucci; L., Cellai; S., Cerrini; DI FILIPPO, Patrizia; D., Lamba. - In: HELVETICA CHIMICA ACTA. - ISSN 0018-019X. - 75:(1992), pp. 153-159. [10.1002/hlca.19920750112]
X-ray crystal structure of 25-O-deacetyl-27,28-didehydro-27-demethoxy-11-deoxo-11,29-epoxy-28,29- dihydro-21,23-O-isopropylidenerifamycin S
DI FILIPPO, PATRIZIA;
1992
Abstract
In search of new types of semisynthetic derivatives of the natural antibiotic rifamycin S (1), we synthesized 25‐O‐deacetyl‐27,28‐didehydro‐27‐demethoxy‐11‐deoxo‐11,29‐epoxy‐28, 29‐dihydro‐21,23‐O‐isopropyli‐denerifamycin S (3). Its X‐ray crystal structure shows a new type of ansa‐chain with an 11,29‐epoxy moiety, the loss of the MeO group on C(27), and the shift of the CC bond from C(28),C(29) to C(27),C(28). These modifications result in a conformational rearrangement of the whole ansa‐chain, nonetheless the overall spatial shape of the molecule is still close to that of most rifamycins. As found in other 11‐deoxo‐11‐hydroxyrifamycin‐S derivatives, the chromophore rings of 3 give rise to π‐π association in the crystal.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
