Patent ID: 7470719

Claim:
A metastable form of a compound of formula I: in which n represents 1 and R, in position 7, represents methoxy, said metastable form having a melting point of 151 to 153° C. as measured by differential thermal analysis by scanning between 40 and 180° C. at a rate of 10° C./minute, and an X-ray diffraction spectrum defined by the absorption wavelengths in Table I below: Absorption Percentage of No. wavelength (cm−1) transmission (%) Intensity 1 620.27 0.660 m 2 844.38 0.892 w 3 679.11 0.865 w 4 709.98 0.568 m 5 730.24 0.907 w 6 736.03 0.891 w 7 745.67 0.849 w 8 761.11 0.843 w 9 814.16 0.518 m 10 839.24 0.683 m; 11 849.85 0.889 w 12 869.15 0.660 m 13 878.79 0.466 s 14 899.05 0.936 w 15 925.10 0.755 m 16 951.14 0.740 m 17 966.58 0.688 m 18 973.33 0.587 m 19 987.80 0.815 w 20 1028.31 0.641 m 21 1046.64 0.517 m 22 1052.43 0.562 m 23 1064.97 0.859 w 24 1128.64 0.825 w 25 1168.19 0.797 w 26 1190.37 0.422 s 27 1199.06 0.408 s 28 1212.56 0.441 s 29 1251.15 0.442 s 30 1270.44 0.254 s 31 1295.52 0.659 m 32 1318.67 0.825 w 33 1355.33 0.769 w 34 1391.98 0.872 w 35 1393.91 0.872 w 36 1413.21 0.651 m 37 1432.50 0.806 w 38 1464.33 0.743 m 39 1494.24 0.511 m 40 1572.37 0.707 m 41 1599.38 0.284 s 42 1623.50 0.810 w 43 1663.05 0.650 m 44 1676.55 0.458 s 45 2837.99 0.863 w 46 2871.75 0.847 w 47 2934.45 0.819 w 48 2960.50 0.818 w 49 3018.38 0.898 w in which w means weak intensity, s means strong intensity, and m means medium intensity.