TY  - JOUR
A1  - Schilde, Uwe
A1  - Kelling, Alexandra
A1  - Umbreen, Sumaira
A1  - Linker, Torsten
T1  - Crystal structures of three bicyclic carbohydrate derivatives
JF  - Acta crystallographica Section E ; Crystallographic communications
N2  - The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis(acetyloxy)-7-oxo-2-oxabicyclo-
[4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acetyloxy-7-
hydroxyimino-2-oxobicyclo[4.2.0]octan-4-yl acetate, C11H15NO6, (II), and
[(3aR,5R,6R,7R,7aS)-6,7-bis(acetyloxy)-2-oxooctahydropyrano[3,2-b]pyrrol-5-
yl]methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives.
They can easily be synthesized in a few steps from commercially available
glycals. As a result of the ring strain from the four-membered rings in (I) and
(II), the conformations of the carbohydrates deviate strongly from the ideal
chair form. Compound (II) occurs in the boat form. In the five-membered
lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair
conformation. As a result of the distortion of the sugar rings, the configurations
of the three bicyclic carbohydrate derivatives could not be determined from
their NMR coupling constants. From our three crystal structure determinations,
we were able to establish for the first time the absolute configurations of all new
stereocenters of the carbohydrate rings.
KW  - crystal structure
KW  - carbohydrate deriv­atives
KW  - conformation
KW  - configuration
Y1  - 2016
U6  - https://doi.org/10.1107/S2056989016018727
SN  - 2056-9890
VL  - 72
IS  - 12
SP  - 1839
EP  - 1844
PB  - IUCR
CY  - Chester
ER  - 
TY  - JOUR
A1  - Schilde, Uwe
A1  - Paz, Christian
A1  - Ortiz, Leandro
T1  - Crystal structure of erioflorin isolated from Podanthus mitiqui (L.)
JF  - Acta Crystallographica Section E : Crystallographic Communications
N2  - The title compound, erioflorin, C19H24O6 [systematic name: (1aR,3S,4Z,5aR,8aR,9R,10aR)-1a, 2,3,5a, 7,8,8a, 9,10,10a-decahydro-3-hydroxy-4,10a-dimethyl-8-methylidene-7-oxooxireno[5,6] cyclodeca[1,2-b]furan-9-yl methacrylate], is a tricyclic germacrane sesquiterpene lactone, which was isolated from Podanthus mitiqui (L.). The compound crystallizes in the space group P2(1)2(1)2(1), and its molecular structure consists of a methacrylic ester of a ten-membered ring sesquiterpenoid annelated with an epoxide and a butyrolactone. The structure is stabilized by one intramolecular C-H center dot center dot center dot O hydrogen bond. An O-H center dot center dot center dot O hydrogen bond and further C-H center dot center dot center dot O interactions can be observed in the packing.
KW  - crystal structure
KW  - germacrane sesquiterpene lactone
KW  - Podanthus mitiqui
Y1  - 2017
U6  - https://doi.org/10.1107/S2056989017001700
VL  - 73
IS  - 3
SP  - 334
EP  - 337
PB  - International Union of Crystallography
CY  - Chester
ER  -