PIOGLITAZONE

Pioglitazone

5-[[4-[2-(5-ethyl-2-pyridinyl)-ethoxy]phenyl] methyl]- 2,4- thiazolidinedione

5-{4-[2-(5-Ethyl-pyridin-2-yl)-ethoxy]-benzyl}-2,4-thiazolidene dione

cas  111025-46-8

 5-[[4-[2-(5-Ethyl-2-pyridinyl)ethoxy]phenyl]methyl]-2,4-thiazolidinedione

Additional Names: (±)-5-[p-[2-(ethyl-2-pyridyl)ethoxy]benzyl]-2,4-thiazolidinedione
http://newdrugapprovals.org/2014/10/11/pioglitazone/

US 2014088127

http://www.google.com/patents/US20140088127

5-[4-[2-(5-ethylpyridyl)ethoxy]benzyl-2,4-thiazolidinedione (Pioglitazone hydrochloride, R in 1 is 5-ethyl).

EXAMPLE 55

5-{4-[2-(5-Ethyl-pyridin-2-yl)-ethoxy]-benzyl}-2,4-thiazolidene dione (1)

To 5 g (0.0121 mol) of 5-{4-[2-chloro-2-(5-ethyl-pyridin-2-yl)-ethoxy]-benzyl}-2,4-thiazolidene dione dissolved in 25 mL acetic acid was added 1.62 (0.0243 mol) g zinc in 5 min. Stirring continued for 15 hours at 25-30° C. Reaction mixture was poured in excess water, made alkaline using 10% Na2CO3 and extracted with ethyl acetate. After distilling off ethyl acetate in vacuo, methanol was added to precipitate out 1.13 g (25%) g of the crystalline solid product. The two impurities identified in this reaction were 5-ethyl-2-vinyl-pyridine 0.128 g (10%) and 5-(4-hydroxy benzyl)-thiazolidin-2,4-dione 0.342 g (12%).

The product obtained was characterized by IR, Mass, 13C NMR, and 1H NMR, which are as given below. pioglitazone base

IR spectrum (cm−1): 3417 (N—H str.), 1693, 1743 (C═O str.), 1037 (C—O—C str.)

Mass spectrum (m/z) 357.1 (M+H)+

13C-NMR (DMSO-d6): δ 176.5, 172.5, 157.8, 152.1, 145.9, 142.0, 141.1, 131.2, 129.9, 127.8, 115.2, 66.2, 53.8, 37.0, 33.2, 25.4, 15.5

1H-NMR (DMSO-d6): δ 12.0 (1H, s), 6.84-8.71 (7H, m), 4.86 (1H, dd), 4.38 (2H, t), 3.48 (2H, t), 3.25 (1H, dd), 3.04 (1H, dd), 2.75 (2H,q), 1.21 (3H, t)

Melting point 172-175° C.

The final product was dissolved into 12 mL methanol and 0.05 mL con. HCl was added into it at 25° C. Reaction mixture was refluxed for 30 min. and cooled to 10° C. Precipitated hydrochloride salt was filtered off and dried to yield 1.1 g (22%) of the salt, which was characterized by IR, Mass, 13C NMR and 1H NMR, which are as given below.

pioglitazone hydrochloride

IR spectrum (cm−1): 3257 (N—H str.), 1689, 1743 (C═O str.), 1155, 1244 (C—O—C str.)

Mass spectrum (m/z): 357.1 (M+H)+

13C-NMR (DMSO-d6): δ 175.7, 171.7, 157.0, 151.0, 141.1, 129.0, 145.4, 139.8, 127.2, 130.4, 114.4, 65.4, 53.0, 39.2, 36.2, 24.6, 14.6

1H-NMR (DMSO-d6): δ 12.09 (1H, s), 6.82-8.7 (7H, m), 4.8 (1H, dd), 4.38 (2H, t), 3.5 (2H, t), 3.0 (2H, m), 2.75 (2H,q), 1.21 (3H, t)

Melting point: 190-193° C.

http://newdrugapprovals.org/2014/10/11/pioglitazone/