TRITERPENES .102. CRYSTAL-STRUCTURE AND CONFORMATION OF RING A OF BETA-BROMO-19-BETA,28-EPOXY-18-ALPHA-OLEANAN-3-ONE

Authors
NOVOTNY J PODLAHA J KLINOT J
Citation
J. Novotny et al., TRITERPENES .102. CRYSTAL-STRUCTURE AND CONFORMATION OF RING A OF BETA-BROMO-19-BETA,28-EPOXY-18-ALPHA-OLEANAN-3-ONE, Collection of Czechoslovak Chemical Communications, 58(11), 1993, pp. 2737-2744
Citations number
23
Categorie Soggetti
Chemistry
Journal title
Collection of Czechoslovak Chemical Communications → ACNP
ISSN journal
00100765
Volume
58
Issue
11
Year of publication
1993
Pages
2737 - 2744
Database
ISI
SICI code
0010-0765(1993)58:11<2737:T.CACO>2.0.ZU;2-0
Abstract
The crystal structure of 2beta-bromo-19beta,28-epoxy-18alpha-oleanan-3 -one was elucidated. The crystal is orthorhombic, P2(1)2(1)2(1), a = 9 .686(1), b = 14.355(2), c = 19.687(4) angstrom, Z = 4, R = 0.042 for 2 410 observed reflections. Rings B, C, D and E adopt the chair conform ation, the five-membered ether cycle in ring E occurs in the envelope form. Ring A takes the twist-boat conformation turned towards the clas sical boat with C2 and C5 in the stem-stern positions, in contrast to the conformation in solution, which is turned in the opposite directio n towards the classical boat with C3 and C10 in the stem-stern positio ns.