As per patent office journal dated 06/08/2021, patent number 373139 has been granted to NATIONAL INSTITUTE OF PHARMACEUTICAL EDUCATION AND RESEARCH (NIPER) that is titled CAN IMPROVED PROCESS FOR THE PREPARATION OF SULFONYLUREAS. The primary independent claim of this patent states a process to produce compound and salts thereof by reacting a compound of the formula with an acyclic carbonate ester compound in the presence of first solvent and at an appropriate temperature to form a mixture and further extracting the mixture obtained, with an organic solvent to separate the extracts of compounds of the formula II. The extracts of compounds of formula (II) obtained is washed with basic solvents followed by concentration and purification to obtain the compounds of formula (II). the compounds of formula II formed reacted with sulfonamide compound of formula III in the presence of organic base, and optionally in presence of aqueous or organic solvents at a reflux temperature to form a crude product, purification of the crude products formed to obtain the compound of formula I, wherein, R 1 is selected from group comprising C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkenyl, C1- C8 alkynyl, C3-C8 cycloalkyl, C1-C8 alkyl- C3-C8 cycloalkyl, C6-C14 aryl, C6-C14 aryl- C1-C8 alkyl; wherein aryl or arylalkyl is unsubstituted or substituted by X group on one or all position or various combinations of mono, di and tri substitutions involving ortho, meta and para positions; X is each and independently selected from any of hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkenyl, C1-C8 alkynyl, -(CH2)p1CF3, halogen, hydroxyl, acetoxy, -NH2, – NRaR b , -NO2, -OCF3, -CONRaR b , -COORa , -CORa , -(CH2)p2NRaR b , -(CH2)p3CH3, – (CH2)p4SORaR b , -(CH2)p5SO2R a , -(CH2)p6SO2NRa , Ra and Rb is each and independently selected from hydrogen, a branched or straight C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkenyl, C1-C8 alkynyl, C3-C8 cycloalkyl, C1-C8 alkyl- C3-C8 cycloalkyl, and wherein p 1 , p 2 , p 3 , p 4 , p 5 , p 6 is each and independently 0, 1 or 2, and is also selected from the R 2 and R3 are each and independently selected from any of hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkenyl, C1-C8 alkynyl, C3-C8 cycloalkyl, C1-C8 alkyl- C3-C8 cycloalkyl, C6-C14 aryl, C6-C14 aryl- C1-C8 alkyl; wherein aryl or arylalkyl is unsubstituted or substituted by one or more heteroatoms selected from S, N, and O, and wherein the aryl and heteroaryl may optionally and independently be substituted by 1 or 2 substituent Y; Wherein Y is each and independently selected from any of hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkenyl, C1-C8 alkynyl, -(CH2)p1CF3; halogen, C1-C8 alkoxy; hydroxyl, -NO2, -OCF3, -CONRaR b ,-COORa , -CORa , -(CH2)p2NRaR b , -(CH2)p3CH3, – (CH2)p4SORaR b , -(CH2)p5SO2R a , -(CH2)p6SO2NRa , Ra and Rb is each and independently selected from hydrogen, a branched or straight C1-C8 alkyl, C1-C8 alkoxy, C1-C8 alkenyl, C1-C8 alkynyl, C3-C8 cycloalkyl, C1-C8 alkyl- C3-C8 cycloalkyl, and wherein p 1 , p 2 , p 3 , p 4 , p 5 , p 6 is each and independently 0, 1 or 2; and pharmaceutically acceptable salts.
During the patent prosecution, the patent examiner objected to this patent under section 3(d) of the Indian Patents Act. The patent applicant responded to this objection by stating that in the present invention, the carbamate can be prepared by reacting an amine with an acyclic carbonate ester in aqueous or aqueous-organic solvents without using any base. This novel & inventive feature is not disclosed or suggested by any prior art documents. Moreover, no hazardous reagents were used. Therefore, the present invention does not fall under section 3(d) of the Patents Act.
This patent falls under the category of Chemical. Overall, this patent covers a process for the preparation of sulfonylurea compounds of formula I as anti-diabetic agents with high purity and yield and without the use of any hazardous reagents. The preparation of various sulfonylureas starts from the reaction of various amines with diphenyl carbonate to produce the corresponding carbamates, which subsequently react with a sulphonamide to produce the desired sulfonylureas of general formula I.
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