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Synthesis, Reactivity Studies, and X‐ray Crystal Structure of (11 R )‐25‐ O ‐Deacetyl‐11‐deoxo‐11‐hydroxy‐21,23‐ O ‐isopropylidenerifamycin S
Author(s) -
Bartolucci Cecilia,
Cellai Luciano,
Cerrini Silvio,
Lamba Doriano,
Segre Anna Laura,
Brizzi Vittorio,
Brufani Mario
Publication year - 1990
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19900730122
Subject(s) - chemistry , acylation , reactivity (psychology) , stereochemistry , crystal structure , substrate (aquarium) , combinatorial chemistry , catalysis , organic chemistry , medicine , oceanography , alternative medicine , pathology , geology
The protected intermediate (11 R )‐25‐ O ‐deacetyl‐11‐deoxo‐11‐hydroxy‐21,23‐ O ‐isopropylidenerifamycin S ( 7 ) has been synthesized starting from rifamicin S ( 2 ; Scheme 2 ), the former being a potential substrate for the preparation of new types of rifamicin‐S derivatives modified at C(11) and/or C(25). The reactivity of 7 toward acylations has been studied under both base‐ and acid‐catalyzed conditions. The compound either did not react or nr underwent unexpected reactions, and no acylation products could be isolated. The X‐ray crystal structure of 7 reveals that both OH groups at C(11) and C(25) are hindered, and this is probably the reason, why other take place faster than acylation.