Nine bis-9,10-dihydrophenanthrene and 9,10-dihydrophenanthrene/(dihydro)stilbene derivatives, including the new phochinenins G-L 1–6, were isolated from the whole plant of Pholidota chinensis. Their structures were elucidated on the basis of extensive spectroscopic investigations (1D, 2D NMR, and HREIMS). Owing to the sterically hindered rotation around the biaryl axis, some of these biaryl compounds can exist as a pair of enantiomers, but were isolated as racemates. Computed inversion barriers of selected atropisomeric derivatives suggested that phochinenins K 5, gymconpin C 7, and flavanthrin 9 have stable atropisomers. Their racemates were separated by HPLC on an optically active stationary phase, and were stereochemically characterized on-line by circular dichroism (CD) spectroscopy (LCCD coupling), in conjunction with quantum-mechanics CD calculations.
|Autori:||YAO SHENG; TANG CHUNG-PING; YE YANG; KURTAN TIBOR; KISS-SZIKSZAI ATTILA; ANTUS SANDOR; PESCITELLI GENNARO; SALVADORI P; KROHN KARSTEN|
|Titolo:||Stereochemistry of atropisomeric 9,10-dihydrophenanthrene dimers from Pholidota chinensis|
|Anno del prodotto:||2008|
|Digital Object Identifier (DOI):||10.1016/j.tetasy.2008.08.013|
|Appare nelle tipologie:||1.1 Articolo in rivista|