Crystalline Forms of Isobutyric acid 2-(3-(diisopropylamino)-1(R)-phenylpropyl)-4- (hydroxymethyl)phenyl ester hydrogen base (17-Nov-2009)

Crystalline Isobutyric acid 2-(3-(diisopropylamino)-1(R)-phenylpropyl) -4- (hydroxymethyl) phenyl ester

    Isobutyric acid 2-(3-(diisopropylamino)-1(R)-phenylpropyl) -4- (hydroxymethyl) phenyl ester ("FST base") of the following structure,

is an intermediate in the synthesis of isobutyric acid 2-(3-(diisopropylamino)-1(R)- phenylpropyl)-4-(hydroxymethyl)phenyl ester hydrogen fumarate ("FSTF"), which is a selective M3 antimuscarinic agent indicated for the treatment of overactive bladder syndrome with symptoms of urgency urinary incontinence and increased urinary frequency. FSTF is marketed under the trade name Toviaz® by Pfizer.

A crystalline form of FST base was found and is described herein below.

    The crystalline form of FST base can be characterized by an X-ray powder diffraction having peaks at about 8.8, 10.8, 11.4, 12.5, 13.0, 13.8, 14.2, 15.6, 16.0, 16.8,
17.3, 17.6, 19.0, 20.3, 20.6, 21.4, 21.8, 22.5, 23.5, 24.2, 25.0, 27.6, 33.4 and 34.8 ± 0.2 degrees two-theta and a PXRD pattern as depicted in Figure 1.

Fig.1 PXRD pattern of FST base crystalline form

    Crystalline FST base can be further characterized by an FT-IR spectrum having peaks at about 3595, 3405, 2983, 2713, 1741, 1621, 1496, 1469, 1387, 1354, 1213, 1177, 1137, 1034, 983, 921, 871, 820 and 700 cm^-1 ± 4 cm^-1 and...