
TY  - JOUR
A1  - Castleden, IR 
A1  - Hall, SR 
A1  - Nimgirawath, S 
A1  - Thadaniti, S 
A1  - White, AH 
T1  - The Flavonoids of <i>Combretum quadrangulare</i>: Crystal structures of the Polymorphic Forms of 5-Hydroxy-2-(4'-hydroxy-3',5'-dimethoxyphenyl)-3,7-dimethoxy-4<i>H</i>-1-benzopyran-4-one
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1985
VL  - 38
IS  - 8
SP  - 1177
EP  - 1185
KW  - 
UR  - https://doi.org/10.1071/CH9851177 
N2  - The following substituted 2-phenyl-4H-1-benzopyran-4-ones have been isolated from the dried flowers of Combretum quadrangulare Kurz ( Combretaceae ): 5-hydroxy-3,3&#8242;,4&#8242;,5&#8242;,7-pentamethoxy ( combretol ) (1), 3&#8242;,5-dihydroxy-3,4&#8242;,7-trimethoxy ( ayanin ) (2) and 4&#8242;,5-dihydroxy- 3,3&#8242;,5&#8242;,7-tetramethoxy (3). The last substance (3) was obtained as a mixture of two polymorphic forms (&#945; and &#946;) each of which was characterized by X-ray diffraction. Diffractometer data at 295 K were refined by full matrix least squares to residuals of 0.043 (1181 'observed' reflections) for the &#945;-phase and 0.044 (1421) for the &#946; phase of (3). Crystals of the &#945;-phase of (3) are triclinic, P&#299;, a 12.663(6), b 9.592(4), c 7.444(4) &#506;, &#945; 102.48(3), &#946; 101.39(4), &#947; 91.72(4)&#176;,Z 2. Crystals of the &#946;-phase of (3) are monoclinic P21/n, a 17.139(8), b 12.728(6), c 7.845(7) &#506;, &#946; 95.07(6)&#176;, Z 4. An unambiguous synthesis of (3) was also achieved. 
ER  -

