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N–N‐Coupled Indolo‐sesquiterpene Atropo‐Diastereomers from a Marine‐Derived Actinomycete
Author(s) -
Zhang Qingbo,
Mándi Attila,
Li Sumei,
Chen Yuchan,
Zhang Wenjun,
Tian Xinpeng,
Zhang Haibo,
Li Huixian,
Zhang Weimin,
Zhang Si,
Ju Jianhua,
Kurtán Tibor,
Zhang Changsheng
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201200599
Subject(s) - chemistry , atropisomer , diastereomer , stereocenter , chirality (physics) , stereochemistry , axial chirality , sesquiterpene , nitrogen inversion , nitrogen , organic chemistry , enantioselective synthesis , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , quark , catalysis
Four new indolo‐sesquiterpenes – dixiamycins A ( 1 ) and B ( 2 ), oxiamycin ( 3 ), and chloroxiamycin ( 4 ) – were isolated from a marine‐derived Actinomycete and characterized, together with the known compound xiamycin A ( 5 ). Dixiamycins A ( 1 ) and B ( 2 ) are the first examples of atropisomerism of naturally occurring N‐N‐coupled atropo‐diastereomers, with a dimeric indolo‐sesquiterpene skeleton and a stereogenic N‐N axis between sp 3 ‐hybridized nitrogen atoms. Solution TDDFT ECD calculations were utilized to ascertain the axial chirality of 1 and 2 , and rotational barriers and transitions states of the inversion were calculated. Oxiamycin ( 3 ) contains a seven‐membered 2,3,4,5‐tetrahydrooxepine ring. The two dimeric compounds 1 and 2 showed better antibacterial activities than the monomers 3 – 5 .