Piretanide

Chemical Name 3-N-Pyrrolidino4-phenoxy-5-sulfamylbenzoic acid Common Name — 

3-N-Succinimido4-phenoxy-5-sulfamylbenzoic acid methyl ester Sodium borohydride Sodium hydroxide 

3 g (0.03 mol) of 3-N-succinimido-4-phenoxy-5-sulfamylbenzoic acid methyl ester are dissolved or suspended in 100 ml of absolute diglyme. 9 g of boron trifluoride etherate are added direct to this mixture and a solution of 2.4 g ( 0.063 mol) of NaBH4 in BO ml of diglyme is then added dropwise at room temperature with stirring. As the reaction proceeds exothermically, It is necessary to cool with ice water. The reaction is normally complete after the drop-wise addition and a short period of stirring thereafter. 

The excess reducing agent is then decomposed by means of a little water (foaming), the solution is filtered and about 300 ml of water are added while stirring. The 3-N-pyrrolidino-4-phenoxy-5-sulfamylbenzoic acid methyl ester which has crystallized out is recrystallized from methanol in the form of colorless crystals, melting point 191°C to 192°C. 

61 g of 3-N-pyrrolidino4-phenoxy-5-sulfamylbenzoic acid methyl ester are suspended in 350 ml of 1 N NaOH and the suspension Is heated for one hour on the waterbath. 3-N-pyrrolidino-4-phenoxy-5-suifamylbenzoic acid is precipitated from the clear solution by means of 2 N HCI while stirring well. The almost pure crude product can be recrystallized from methanol/water in the form of light yellow platelets, melting point 225°C to 227°C, with decomposition. 

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It has been documented in an earlier volume that appropriately substituted molecules with two strongly electron withdrawing substituents meta to one another in a benzene ring often possess diuretic properties and, even though the prototypes usually have two substituted sulfonamide moieties so disposed, other groups can replace at least one of them. An example of this is piretanide (24), where one such group is a carboxyl... 

Some compounds are capable of forming solvates with a variety of solvents, and DSC can be effectively used to screen the various species that may be isolated from the different systems. Piretanide [34] provides a typical example of this behavior, for which representative DSC thermograms have been illustrated in Fig. 12. After recrystallization of this compound from 27 different solvents, six... 

Fig. 12 Differential scanning calorimetry thermograms obtained for piretanide, as recrystallized from (a) f-butanol, (b) n-propanol, (c) i-propanol, and (d) IV V-dimethyl-formamide. (Data adapted from Ref. 34.)...

Loop diuretics include furosemide (frusemide), piretanide, and bumeta-nide. With oral administration, a strong diuresis occurs within 1 h but persists for only about 4 h. The effect is rapid, intense, and brief (high-ceiling diuresis). 

Chikarishi, Y., Sano, A., Tsujiyama, T., Otsuka, M., and Matsuda, Y. (1994). Preparation of piretanide polymorphs and their physicochemical properties and dissolution behaObEsp. Pharm. BulJ. 42 1123-1128. 

High-ceiling diuretics, sulfonamide (furosemide, bumetanide, torasemide, piretanide)... 

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