ABSTRACT
Objective To investigate the structure and optical activity of flavonoid derivative:2-(3,4-dimethoxyphenyl)-4-oxo-4 H-chromen-3-yl acetate(4).Methods The absolute configuration was obtained by X-ray single crystal diffraction.The optical rotation of the compound was determined by the SGW ?R-1 automatic polarimeter.Results X-ray single crystal diffrac-tion showed that compound 4 belongs to the orthorhombic space group P212121with a=7.763(2)?A,b=13.930(4)?A and c=14.906(4),α= β= γ=90.00°,V =1611.91(8)?A3,Z=8.There is no hydrogen bonding between the molecules in this crystal state.The molecules maintain their stable arrangement in space by van der Waals forces.It can be seen from the single-crystal data that there is a 33.9(2)° torsion of the dimethoxy-substituted benzene ring in the compound 4 with respect to the 4 H-chromene skeleton,suggesting that there may exist optical activity.Further experimental results of the optical rotation proved that the compound has a L-rotatory,specific rotation[α]19.1D = -5.077°.Conclusion The results of the single crystal indicated that the benzene ring substituted with dimethoxy group in compound 4 has a 33.9(2)° torsion relative to the 4 H-chromene skeleton,which results in chirality and optical activity.This is the first report that non-flavonoid-glycoside has optical activity.
ABSTRACT
Three new compounds, namely siderochelins D (2), E (3), and F (4), together with one known siderochelin A (1), were isolated from Amycolatopsis sp. LZ149 and elucidated by spectroscopic analyses including1D- and 2D-NMR and X-ray single crystal diffraction. Compounds 1-3 showed antibacterial activity against Mycobacterium smegmatis.