Shridhara Bhat K - Academia.edu (original) (raw)
Papers by Shridhara Bhat K
Journal of Chemical Sciences, 2022
In the present work, a novel prodrug has been synthesized to enhance the therapeutic efficacy of ... more In the present work, a novel prodrug has been synthesized to enhance the therapeutic efficacy of a renowned antimalarial drug, Atovaquone. Prodrug of the present work overcomes the challenges associated with the poor solubility of the parent drug, Atovaquone and thus contributes to increased drug bioavailability. The present study summarizes the synthesis, characterization and reaction condition optimizations in a systematic pathway. The present disclosure provides a consistent and repeatable reaction conditions for the synthesis of Atovaquone prodrug in high yields and good purity. Compact reaction optimization studies enable the synthetic process to be suitable for large scale manufacturing, a significant initiative towards commercialization of the prodrug. Graphical abstract SYNOPSIS Atovaquone is a well known antimalarial drug that has poor water solubility and low bioavailability. To overcome these challenges, a novel prodrug of Atovaquone has been synthesized. Synthesis, structural elucidation and reaction optimization studies of the novel prodrug has been explained with supportive experimental and spectral results. The collective experimental output enables large-scale manufacturing of the disclosed prodrug 3 with substantial high yields and purity.
Objective: N-substituted derivatives of 6-fluoro-1-methyl-4-oxo-7-(piperazin-1-yl)-4H-[1, 3] thia... more Objective: N-substituted derivatives of 6-fluoro-1-methyl-4-oxo-7-(piperazin-1-yl)-4H-[1, 3] thiazeto [3, 2-a] quinoline-3-carboxylic acid: Synthesis and antibacterial activity. Methods: In the present study N-substituted derivatives of 6-fluoro-1-methyl-4-oxo-7-(piperazin-1-yl)-4H-[1,3]thiazeto[3,2-a]quinoline-3carboxylic acid were prepared by using Triethylamine and DMF. This procedure was modified by adding tetra butyl ammonium bromide (TBAB) to facilitate completion in few reactions. Other reactions which did not proceed in both the aforementioned ways were facilitated by the use of Morwet-D425. All the new title compounds were characterized by their spectral data and were screened for antibacterial activity. Results: Some of the reported compounds were synthesized using the process disclosed by us in U.S.Pat.No.8, 410,268B2. In our present work, we have achieved good yields and purity. Many compounds exhibited substantial antibacterial activity. Conclusion: It can be inferred t...
The synthes is of a number of I ,3,4-oxadiazoles 6a-c is described . 2-Chloropyridine-5-aeeti c a... more The synthes is of a number of I ,3,4-oxadiazoles 6a-c is described . 2-Chloropyridine-5-aeeti c acid 3 is prepared starting from eas il y available 2-chloro-5-chloromethy lpyridine 1. via 2-chloro-5 -cyanomethy lpyridine 2. L <lerification of 3 with methanol in the presence of H2S04 gives the corresponding meth yl ester 4. Hydrazinolysis of 4 with hydrazin hydrate affords 2-chloropyri dine-5-acetic acid hydrazide 5. Hydrazide 5 on reacting with aroyl chlorides in the presence of POCI .. y ields 2-chloro-5-(5-ary l1 ,3,4-oxadiazol-2-y l) lllethy lpyridines 6a-c.
ChemInform, 2002
Reactions of 3-aryloxymethyl-4-amino-5-mercapto-1 ,2,4-triazoles 1 with aromatic carboxylic acids... more Reactions of 3-aryloxymethyl-4-amino-5-mercapto-1 ,2,4-triazoles 1 with aromatic carboxylic acids, furoic acid, oxalic acid, monoch10roacetic acid and phenacyl bromide furnish various N-bridged heterocycles viz., triazolothiadiazoles, bis triazolothiadiazoles, triazolothiadiazinones and triazolothiadiazines . The structures of these N-bridged heterocycles are characterized on the basis of elemental analyses, IR, NMR and mass spectral data. Some of these compounds are also subjected to antibacterial screening studies. The pharmacological importance of nitrogen bridged heterocycles derived from 1,2,4-triazoles paved the way towards active research in triazole chemistry. As a result, variety of new compounds were being added to this field every year. A number of attempts were made to improve the activity of these compounds by varying the substituents on the triazole nucleus. The literature survey reveals that many N-bridged heterocycles such as triazolothiadiazoles , triazolothiadiazi...
Indian Journal of Chemistry Section B-organic Chemistry Including Medicinal Chemistry, 1991
Journal of Chemical Sciences
Abstract Attempted cyclodehydration of phenacyl mercaptoimidazole hydrobromide with acetic anhydr... more Abstract Attempted cyclodehydration of phenacyl mercaptoimidazole hydrobromide with acetic anhydride gave an abnormal product lacking the phenyl group. The molecular structure is confirmed using X-ray crystal structure studies. Phenacyl mercaptobenzimidazole hydrobromide behaved similarly. Analysis of crystal structure revealed an intermolecular S…Br chalcogen bonding interaction. Graphic abstract The cylization reaction of 2-phenacylmercaptoimidazole hydrobromide is carried out using acetic anhydride, afforded an unexpected imidazothiazole lacking a phenyl ring. The generality of the reaction is confirmed by a similar reaction which was carried out with phenacylmercaptobenzimidazole and yielded similar product
Bollettino chimico farmaceutico
A series of 2-(2-furyl)4-quinolinecarboxylic acids (3), 2-(5-nitro-2-furyl)4-quinolinecarboxylic ... more A series of 2-(2-furyl)4-quinolinecarboxylic acids (3), 2-(5-nitro-2-furyl)4-quinolinecarboxylic acids (6), 4-(3-aryloxymethyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazolo-6-yl)-2-(furyl)quinolines (5) and 4-(3-aryloxymethyl-1.2,4-triazolo[3,4-b]-1,3,4-thiadiazolo-6-yl)-2-(5-nitro-2-furyl)quinolines (7) were synthesized. The structures of the newly synthesized compounds are confirmed on the basis of elemental analysis, IR, 1H-NMR and mass spectral data. The newly synthesized compounds are evaluated for their antibacterial activities. Compounds containing nitrofuran moiety showed excellent antibacterial activity. Results of such studies are disscussed in this paper.
![Research paper thumbnail of Nitroimidazooxazoles(#) Part xxiv, Search for Antileishmanial Agents: 2,3-Dihydro-6-nitroimidazo[2,1-b]oxazoles as Potential Antileishmanial Agents](https://attachments.academia-assets.com/80589432/thumbnails/1.jpg)
](Indian Journal of Pharmaceutical Sciences
A number of mono and bicyclic nitroimidazoles were screened for in vitro antileishmanial activity... more A number of mono and bicyclic nitroimidazoles were screened for in vitro antileishmanial activity. Among these, compounds belonging to the class of nitroimidazo[2,1-b]oxazoles showed moderate to good activity. This class of compounds had been reported previously to have pronounced antitubercular activity, particularly CGI17341 (5a). In the present study (5a) and (5d) and (7) were found to be more potent antileishmanials in vitro than the standard and less toxic in relation to a reference compound. (7) Was earlier formulated to have the phenyl group located on C-2(5b).
ChemInform, 1991
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform, 1992
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform, 1999
Synthesis of Some New Biologically Active Thiadiazolotriazinones. Part. 2.-A variety of antibacte... more Synthesis of Some New Biologically Active Thiadiazolotriazinones. Part. 2.-A variety of antibacterially active thiadiazolotriazinones (III) (15 examples) are synthesized by POCl 3-mediated condensation of 4amino-3-mercaptotriazinones (I) with carboxylic acids (II).-(HOLLA, B.
Farmaco, 2000
A series of 3-substituted-4-[5-(2,4-dichlorophenyl)-2-furfurylidine]amino-5-mercapto-1,2,4-triazo... more A series of 3-substituted-4-[5-(2,4-dichlorophenyl)-2-furfurylidine]amino-5-mercapto-1,2,4-triazoles (3) are synthesised. Aminomethylation of 3 with formaldehyde and a primary/secondary amine furnished Mannich bases 4 and 5. Both Schiff bases 3 and Mannich bases 4 and 5 are characterised on the basis of IR, 1H NMR, mass spectral data and elemental analysis. All the newly synthesised compounds are tested for their antibacterial activities. Some of
4-Amino-6-arylmethyl-3-mercapto-1,2,4-triazin-5(4H)-ones 1 are condensed with aromatic carboxylic... more 4-Amino-6-arylmethyl-3-mercapto-1,2,4-triazin-5(4H)-ones 1 are condensed with aromatic carboxylic acids, aryloxyacetic acids and anilinoacetic acids 2 to yield 7-substituted-3-arylmethyl-4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-tr iazin-4-ones 3. Phosphorus oxychloride is used as cyclizing agent. Some of the newly synthesized compounds are screened for their antibacterial activities.
Organic Process Research & Development, 2010
An improved process has been developed for the synthesis of 5-bromo-3-(1-methylpiperidin-4-yl)-1H... more An improved process has been developed for the synthesis of 5-bromo-3-(1-methylpiperidin-4-yl)-1H-indole, a key intermediate of naratriptan hydrochloride, which is used as a drug for migraine. A novel one-pot synthetic procedure using triethyl silane was developed for scale-up.
Journal of Chemical Sciences, 2022
In the present work, a novel prodrug has been synthesized to enhance the therapeutic efficacy of ... more In the present work, a novel prodrug has been synthesized to enhance the therapeutic efficacy of a renowned antimalarial drug, Atovaquone. Prodrug of the present work overcomes the challenges associated with the poor solubility of the parent drug, Atovaquone and thus contributes to increased drug bioavailability. The present study summarizes the synthesis, characterization and reaction condition optimizations in a systematic pathway. The present disclosure provides a consistent and repeatable reaction conditions for the synthesis of Atovaquone prodrug in high yields and good purity. Compact reaction optimization studies enable the synthetic process to be suitable for large scale manufacturing, a significant initiative towards commercialization of the prodrug. Graphical abstract SYNOPSIS Atovaquone is a well known antimalarial drug that has poor water solubility and low bioavailability. To overcome these challenges, a novel prodrug of Atovaquone has been synthesized. Synthesis, structural elucidation and reaction optimization studies of the novel prodrug has been explained with supportive experimental and spectral results. The collective experimental output enables large-scale manufacturing of the disclosed prodrug 3 with substantial high yields and purity.
Objective: N-substituted derivatives of 6-fluoro-1-methyl-4-oxo-7-(piperazin-1-yl)-4H-[1, 3] thia... more Objective: N-substituted derivatives of 6-fluoro-1-methyl-4-oxo-7-(piperazin-1-yl)-4H-[1, 3] thiazeto [3, 2-a] quinoline-3-carboxylic acid: Synthesis and antibacterial activity. Methods: In the present study N-substituted derivatives of 6-fluoro-1-methyl-4-oxo-7-(piperazin-1-yl)-4H-[1,3]thiazeto[3,2-a]quinoline-3carboxylic acid were prepared by using Triethylamine and DMF. This procedure was modified by adding tetra butyl ammonium bromide (TBAB) to facilitate completion in few reactions. Other reactions which did not proceed in both the aforementioned ways were facilitated by the use of Morwet-D425. All the new title compounds were characterized by their spectral data and were screened for antibacterial activity. Results: Some of the reported compounds were synthesized using the process disclosed by us in U.S.Pat.No.8, 410,268B2. In our present work, we have achieved good yields and purity. Many compounds exhibited substantial antibacterial activity. Conclusion: It can be inferred t...
The synthes is of a number of I ,3,4-oxadiazoles 6a-c is described . 2-Chloropyridine-5-aeeti c a... more The synthes is of a number of I ,3,4-oxadiazoles 6a-c is described . 2-Chloropyridine-5-aeeti c acid 3 is prepared starting from eas il y available 2-chloro-5-chloromethy lpyridine 1. via 2-chloro-5 -cyanomethy lpyridine 2. L <lerification of 3 with methanol in the presence of H2S04 gives the corresponding meth yl ester 4. Hydrazinolysis of 4 with hydrazin hydrate affords 2-chloropyri dine-5-acetic acid hydrazide 5. Hydrazide 5 on reacting with aroyl chlorides in the presence of POCI .. y ields 2-chloro-5-(5-ary l1 ,3,4-oxadiazol-2-y l) lllethy lpyridines 6a-c.
ChemInform, 2002
Reactions of 3-aryloxymethyl-4-amino-5-mercapto-1 ,2,4-triazoles 1 with aromatic carboxylic acids... more Reactions of 3-aryloxymethyl-4-amino-5-mercapto-1 ,2,4-triazoles 1 with aromatic carboxylic acids, furoic acid, oxalic acid, monoch10roacetic acid and phenacyl bromide furnish various N-bridged heterocycles viz., triazolothiadiazoles, bis triazolothiadiazoles, triazolothiadiazinones and triazolothiadiazines . The structures of these N-bridged heterocycles are characterized on the basis of elemental analyses, IR, NMR and mass spectral data. Some of these compounds are also subjected to antibacterial screening studies. The pharmacological importance of nitrogen bridged heterocycles derived from 1,2,4-triazoles paved the way towards active research in triazole chemistry. As a result, variety of new compounds were being added to this field every year. A number of attempts were made to improve the activity of these compounds by varying the substituents on the triazole nucleus. The literature survey reveals that many N-bridged heterocycles such as triazolothiadiazoles , triazolothiadiazi...
Indian Journal of Chemistry Section B-organic Chemistry Including Medicinal Chemistry, 1991
Journal of Chemical Sciences
Abstract Attempted cyclodehydration of phenacyl mercaptoimidazole hydrobromide with acetic anhydr... more Abstract Attempted cyclodehydration of phenacyl mercaptoimidazole hydrobromide with acetic anhydride gave an abnormal product lacking the phenyl group. The molecular structure is confirmed using X-ray crystal structure studies. Phenacyl mercaptobenzimidazole hydrobromide behaved similarly. Analysis of crystal structure revealed an intermolecular S…Br chalcogen bonding interaction. Graphic abstract The cylization reaction of 2-phenacylmercaptoimidazole hydrobromide is carried out using acetic anhydride, afforded an unexpected imidazothiazole lacking a phenyl ring. The generality of the reaction is confirmed by a similar reaction which was carried out with phenacylmercaptobenzimidazole and yielded similar product
Bollettino chimico farmaceutico
A series of 2-(2-furyl)4-quinolinecarboxylic acids (3), 2-(5-nitro-2-furyl)4-quinolinecarboxylic ... more A series of 2-(2-furyl)4-quinolinecarboxylic acids (3), 2-(5-nitro-2-furyl)4-quinolinecarboxylic acids (6), 4-(3-aryloxymethyl-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazolo-6-yl)-2-(furyl)quinolines (5) and 4-(3-aryloxymethyl-1.2,4-triazolo[3,4-b]-1,3,4-thiadiazolo-6-yl)-2-(5-nitro-2-furyl)quinolines (7) were synthesized. The structures of the newly synthesized compounds are confirmed on the basis of elemental analysis, IR, 1H-NMR and mass spectral data. The newly synthesized compounds are evaluated for their antibacterial activities. Compounds containing nitrofuran moiety showed excellent antibacterial activity. Results of such studies are disscussed in this paper.
Indian Journal of Pharmaceutical Sciences
A number of mono and bicyclic nitroimidazoles were screened for in vitro antileishmanial activity... more A number of mono and bicyclic nitroimidazoles were screened for in vitro antileishmanial activity. Among these, compounds belonging to the class of nitroimidazo[2,1-b]oxazoles showed moderate to good activity. This class of compounds had been reported previously to have pronounced antitubercular activity, particularly CGI17341 (5a). In the present study (5a) and (5d) and (7) were found to be more potent antileishmanials in vitro than the standard and less toxic in relation to a reference compound. (7) Was earlier formulated to have the phenyl group located on C-2(5b).
ChemInform, 1991
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform, 1992
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform, 1999
Synthesis of Some New Biologically Active Thiadiazolotriazinones. Part. 2.-A variety of antibacte... more Synthesis of Some New Biologically Active Thiadiazolotriazinones. Part. 2.-A variety of antibacterially active thiadiazolotriazinones (III) (15 examples) are synthesized by POCl 3-mediated condensation of 4amino-3-mercaptotriazinones (I) with carboxylic acids (II).-(HOLLA, B.
Farmaco, 2000
A series of 3-substituted-4-[5-(2,4-dichlorophenyl)-2-furfurylidine]amino-5-mercapto-1,2,4-triazo... more A series of 3-substituted-4-[5-(2,4-dichlorophenyl)-2-furfurylidine]amino-5-mercapto-1,2,4-triazoles (3) are synthesised. Aminomethylation of 3 with formaldehyde and a primary/secondary amine furnished Mannich bases 4 and 5. Both Schiff bases 3 and Mannich bases 4 and 5 are characterised on the basis of IR, 1H NMR, mass spectral data and elemental analysis. All the newly synthesised compounds are tested for their antibacterial activities. Some of
4-Amino-6-arylmethyl-3-mercapto-1,2,4-triazin-5(4H)-ones 1 are condensed with aromatic carboxylic... more 4-Amino-6-arylmethyl-3-mercapto-1,2,4-triazin-5(4H)-ones 1 are condensed with aromatic carboxylic acids, aryloxyacetic acids and anilinoacetic acids 2 to yield 7-substituted-3-arylmethyl-4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-tr iazin-4-ones 3. Phosphorus oxychloride is used as cyclizing agent. Some of the newly synthesized compounds are screened for their antibacterial activities.
Organic Process Research & Development, 2010
An improved process has been developed for the synthesis of 5-bromo-3-(1-methylpiperidin-4-yl)-1H... more An improved process has been developed for the synthesis of 5-bromo-3-(1-methylpiperidin-4-yl)-1H-indole, a key intermediate of naratriptan hydrochloride, which is used as a drug for migraine. A novel one-pot synthetic procedure using triethyl silane was developed for scale-up.