5,3′-Dihydroxy-3,7,4′,5′-tetramethoxyflavone

Abstract

The title compound, C19H18O8 [systematic name: 5‐hydroxy‐2‐(3‐hydroxy‐4,5‐di­methoxy­phenyl)‐3,7‐di­methoxy­chromen‐4‐one], an extract from Premna tomentosa willd, is used in the Siddha system of medicine practiced in South India. The dihedral angle between the mean planes through the benzo­pyran moiety and benzene ring is 38.60 (7)°. A strong O—H·O intramolecular hydrogen bond is observed in the molecular structure. O—H·O and C—H·O hydrogen bonds and π–π interactions stabilize the mol­ecules in the crystal packing.

Chains of edge-fused hydrogen-bondedR33(22) rings in 5,3′-dihydroxy-3,6,7,4′,5′-pentamethoxyflavone

“…1). The bond lengths and angles show normal values and are comparable with those observed in 5,3 H -dihydroxy-3,7,4 H ,5 H -tetramethoxy¯avone (Etti et al, 2005) and calycopterin (Vijayalakshmi et al, 1986). The geometric parameters in the main skeletons of molecules A and B show no signi®cant differences, but they are distinguished by some bond rotations ( Table 1).…”

2-(2-Chlorophenyl)-7-methyl-4H-chromen-4-one

“…It seems like that the π-π stacking interaction is a normal interaction found in flavonoid (Jiang et al, 2002;Etti, et al, 2005;Fun, et al, 2005;Stomberg, et al, 2002). Fig.…”

“…Thestacking interaction observed in the title compound is a normal interaction found in flavonoids (see Jiang et al, 2002;Etti et al, 2005;Fun et al, 2005;Stomberg et al, 2002).…”

“…Thestacking interaction observed in the title compound is a normal interaction found in flavonoids (see Jiang et al, 2002;Etti et al, 2005;Fun et al, 2005;Stomberg et al, 2002). Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL and WinGX (Farrugia, 1999 …”

5,3′-Dihydroxy-3,6,7,4′-tetramethoxyflavone

“…The bond lengths and angles of the flavone ring system in (I) ( Fig. 1) are comparable to those of 5,3 0 -dihydroxy-3,7,4 0 ,5 0tetramethoxyflavone (Etti et al, 2005) and 5-hydroxy-3,7,3 0 ,4 0 ,5 0 ,-pentamethoxyflavone (Dachriyanus et al, 2004). As expected, rings A (C4a/C5-C8/C8a), B (O1/O2/C3/C4/C4a/ C8a) and C (C1 0 -C6 0 ) are planar, the dihedral angles between them being A/B = 2.37 (4) , A/C = 9.49 (3) and B/C = 7.20 (4) .…”