Patents by Inventor Dharmaraj Ramachandra Rao

Dharmaraj Ramachandra Rao has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20150210629
    Abstract: The present invention provides a process for preparing a compound of formula (VI) or a salt thereof, the process comprising: (i) reacting 4-methoxyphenyl acetone with an amine of formula (VIII) under conditions of reductive amination to produce a compound of formula (II) or a salt thereof, wherein there is no isolation of an imine intermediate formed during the reductive amination; (ii) condensing the compound (II) or the acid addition salt thereof with an ?-haloketone of formula (III) to produce the compound of formula (IV); (iii) reducing the compound (IV) to a compound of formula (V); and (iv) reducing the compound (V) to the compound of formula (VI), wherein the reduction is carried out in the presence of either (1) a hydrogen donating compound in the presence of a hydrogen transfer catalyst; or (2) ammonium formate using a hydrogenation catalyst, wherein R1 and R2 are independently optionally substituted arylalkyl, and Hal is selected from chloro or bromo.
    Type: Application
    Filed: April 10, 2015
    Publication date: July 30, 2015
    Inventors: Vaishali Vaman HALDAVANEKAR, Mangesh PRABHU, Dharmaraj Ramachandra RAO, Rajendra Narayanrao KANKAN
  • Publication number: 20150197523
    Abstract: There is provided a process for the preparation of sitagliptin or a pharmaceutically acceptable salt thereof, and a process for the preparation of intermediate compounds useful in the preparation of sitagliptin. In particular, there is provided a process comprising condensing 3-tert-butoxycarbonylamino-4-(2,4,5-trifluorophenyl)butyric acid of formula (II) with 3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine of formula (III) or a salt thereof in presence of a catalyst to obtain (R)-tert-butyl-4-oxo-4-(3-(trifluoromethyl)-5,6-dihydro-[1,2,4]-triazolo[4,3-a]pyrazin-7(8H)-yl)-1-(2,4,5-trifluorophenyl)butan-2-yl-carbamate of formula (IV) or a pharmaceutically acceptable salt thereof. The catalyst is represented by the compound of formula (V). Compound of formula (IV) or its pharmaceutically acceptable salt obtained may be deprotected to obtain a compound of formula (I).
    Type: Application
    Filed: August 8, 2013
    Publication date: July 16, 2015
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Maruti Ghagare, Swati Atul Kadam
  • Publication number: 20150183722
    Abstract: The present invention relates to a compound of formula A, wherein R is alkyl. Compound A may be used as an intermediate in the preparation of O-desmethyl venlafaxine or a salt thereof, and the present invention provides such a preparation, as well as a process for preparing the compound of formula A.
    Type: Application
    Filed: March 16, 2015
    Publication date: July 2, 2015
    Inventors: Rajendra Narayanrao KANKAN, Dharmaraj Ramachandra RAO, Manohar Raghunath SURVE
  • Publication number: 20150141383
    Abstract: There is disclosed crystalline darunavir hydrate substantially free of any non-aqueous solvent.
    Type: Application
    Filed: January 30, 2015
    Publication date: May 21, 2015
    Inventors: Manjinder Singh PHULL, Dharmaraj Ramachandra RAO, Rajendra Narayanrao KANKAN
  • Patent number: 9029421
    Abstract: The present invention provides a process for preparing a compound of formula (VI) or a salt thereof, the process comprising: (i) reacting 4-methoxyphenyl acetone with an amine of formula (VIII) under conditions of reductive amination to produce a compound of formula (II) or a salt thereof, wherein there is no isolation of an imine intermediate formed during the reductive amination; (ii) condensing the compound (II) or the acid addition salt thereof with an ?-haloketone of formula (III) to produce the compound of formula (IV); (iii) reducing the compound (IV) to a compound of formula (V); and (iv) reducing the compound (V) to the compound of formula (VI), wherein the reduction is carried out in the presence of either (1) a hydrogen donating compound in the presence of a hydrogen transfer catalyst; or (2) ammonium formate using a hydrogenation catalyst, wherein R1 and R2 are independently optionally substituted arylalkyl, and Hal is selected from chloro or bromo.
    Type: Grant
    Filed: June 2, 2009
    Date of Patent: May 12, 2015
    Assignee: Cipla Limited
    Inventors: Vaishali Vaman Haldavanekar, Mangesh Prabhu, Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan
  • Patent number: 9018376
    Abstract: The invention relates to various new polymorphic forms of manidipine and pharmaceutically acceptable salts thereof. The invention also relates to processes for the preparation of the polymorphic forms of manidipine and pharmaceutically acceptable salts thereof.
    Type: Grant
    Filed: August 26, 2010
    Date of Patent: April 28, 2015
    Assignee: Cipla Limited
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Maruti Ganpati Ghagare
  • Patent number: 9012689
    Abstract: The present invention relates to a compound of formula A, wherein R is alkyl. Compound A may be used as an intermediate in the preparation of O-desmethyl venlafaxine or a salt thereof, and the present invention provides such a preparation, as well as a process for preparing the compound of formula A.
    Type: Grant
    Filed: July 14, 2010
    Date of Patent: April 21, 2015
    Assignee: Cipla Limited
    Inventors: Rajendra Narayanrao Kankan, Dharmaraj Ramachandra Rao, Manohar Raghunath Surve
  • Patent number: 9000158
    Abstract: In an embodiment, the present invention provides a process for preparing (?)-6-(4-aminophenyl)-5-methylpyridazin-3-(2H)-one, which process comprises: a) reacting racemic 6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone of formula II with a chiral tartaric acid derivative to obtain a diastereomeric salt of (?)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone and the chiral tartaric acid derivative; and b) reacting the diastereomeric salt with a base to obtain (?)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone. The (?)-6-(4-aminophenyl)-4,5-dihydro-5-methyl-3-(2H)-pyridazinone may be used to prepare levosimendan.
    Type: Grant
    Filed: July 12, 2010
    Date of Patent: April 7, 2015
    Assignee: Cipla Limited
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Manjinder Singh Phull, Ashwini Amol Sawant
  • Patent number: 8993789
    Abstract: The present invention provides a process for preparing methyl 5-acetamido-4-amino-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (V), which process comprises reducing methyl 5-acetamido-4-azido-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (IV) in the presence of a reducing agent selected from the group consisting of lithium aluminum hydride, sodium borohydride, zinc/ammonium chloride, zinc-ferric chloride and ferric chloride/sodium iodide. The present invention also provides compounds of formula (VIII) and (IX) which may be used in the synthesis of zanamivir. The present invention also provides processes for preparing compounds (VIII) and (IX) and processes involving their use, including in the synthesis of zanamivir.
    Type: Grant
    Filed: November 24, 2009
    Date of Patent: March 31, 2015
    Assignee: Cipla Limited
    Inventors: Manjinder Singh Phull, Rajendra Narayanrao Kankan, Dharmaraj Ramachandra Rao, Ashwini Amol Sawant, Sanoj Thoppil
  • Patent number: 8987458
    Abstract: The present invention provides a process for preparing donepezil or a salt thereof, the process comprising reducing a 1-benzyl-4-[(5,6-dimethoxy-1-indanon-2-yl)methylene]pyridonium halide of formula II, wherein X is bromide or chloride, in the presence of an ionic compound, a solvent, a catalyst and a source of hydrogen, to form donepezil and optionally converting the donepezil to the salt thereof.
    Type: Grant
    Filed: March 24, 2009
    Date of Patent: March 24, 2015
    Assignee: Cipla Limited
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Srinivas Laxminarayan Pathi
  • Publication number: 20150080579
    Abstract: The present invention provides dexrabeprazole magnesium hydrate and a process for its preparation. The present invention also provides a magnesium, calcium or potassium salt of dexrabeprazole, optionally in amorphous form, and processes for its preparation.
    Type: Application
    Filed: November 19, 2014
    Publication date: March 19, 2015
    Inventors: Dharmaraj Ramachandra RAO, Rajendra Narayanrao KANKAN, Srinivas Laxminarayan PATHI, Dilip Ramdas BIRARI
  • Publication number: 20150045382
    Abstract: There is provided a complex comprising rifaximin and a complexing agent, wherein the complexing agent is a polyvinyl pyrrolidone (PVP) or a cyclodextrin. There is also provided a process for preparing the complex, a pharmaceutical composition including the complex and therapeutic uses of the complex.
    Type: Application
    Filed: October 22, 2014
    Publication date: February 12, 2015
    Inventors: Maruti Ganpati Ghagare, Sunilkumar Parasnath Saroj, Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan
  • Publication number: 20150037275
    Abstract: There is provided a complex comprising rifaximin and a complexing agent, wherein the complexing agent is a polyvinyl pyrrolidone (PVP) or a cyclodextrin. There is also provided a process for preparing the complex, a pharmaceutical composition including the complex and therapeutic uses of the complex.
    Type: Application
    Filed: October 22, 2014
    Publication date: February 5, 2015
    Inventors: Maruti Ganpati Ghagare, Sunilkumar Parasnath Saroj, Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan
  • Patent number: 8916193
    Abstract: There is provided a complex comprising rifaximin and a complexing agent, wherein the complexing agent is a polyvinyl pyrrolidone (PVP) or a cyclodextrin. There is also provided a process for preparing the complex, a pharmaceutical composition including the complex, and therapeutic uses of the complex.
    Type: Grant
    Filed: December 9, 2009
    Date of Patent: December 23, 2014
    Assignee: Cipla Limited
    Inventors: Maruti Ganpati Ghagare, Sunilkumar Parasnath Saroj, Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan
  • Patent number: 8912337
    Abstract: The present invention provides dexrabeprazole magnesium hydrate and a process for its preparation. The present invention also provides a magnesium, calcium or potassium salt of dexrabeprazole, optionally in amorphous form, and processes for its preparation.
    Type: Grant
    Filed: June 24, 2011
    Date of Patent: December 16, 2014
    Assignee: Cipla Limited
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Srinivas Laxminarayan Pathi, Dilip Ramdas Birari
  • Publication number: 20140256004
    Abstract: The present invention relates to a novel process for the preparation of a compound of formula (I) wherein R is a methyl or methoxy group; to certain novel intermediates prepared in such a process and their use.
    Type: Application
    Filed: October 19, 2012
    Publication date: September 11, 2014
    Applicant: CIPLA LIMITED
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Sanjay Naik, Maruti Ghagare, Sandip Vasant Chikhalikar
  • Publication number: 20140194624
    Abstract: A process for the preparation of a salt of N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine comprising reacting a 4-halo-6,7-bis(2-methoxyethoxy)quinazoline with 3-aminophenyl acetylene or an acid salt thereof under acidic conditions to form the corresponding acid salt of N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine, the process optionally further comprising converting the acid salt of N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine to N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine.
    Type: Application
    Filed: January 13, 2014
    Publication date: July 10, 2014
    Applicant: Cipla Limited
    Inventors: Dharmaraj Ramachandra RAO, Rajendra Narayanrao KANKAN
  • Patent number: 8735589
    Abstract: The present invention relates to a process for preparing naratriptan or a salt thereof, the process comprising: (a) reacting a compound of formula (3) with a compound of the formula HCCR wherein Z is a protecting group, Y is a leaving group and R is a trialkyl silyl group, a trialkylstannyl group or a zinc (II) halide, to obtain the compound of formula (4); (b) converting the compound of formula (4) to a compound of formula (5) wherein Z? is hydrogen or a benzyl group; (c) converting the compound of formula (5) to naratriptan; and (d) optionally converting naratriptan to a salt thereof. The present invention also provides novel compounds (3) and (4) and processes for their preparation.
    Type: Grant
    Filed: August 18, 2010
    Date of Patent: May 27, 2014
    Assignee: Cipla Limited
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Sandip Vasant Chikhalikar, Maruti Ghagare
  • Publication number: 20140128419
    Abstract: Amorphous rifaximin, methods of making it, and pharmaceutical compositions containing it. Also described are methods of converting amorphous rifaximin to crystalline rifaximin and vice versa.
    Type: Application
    Filed: January 10, 2014
    Publication date: May 8, 2014
    Applicant: CIPLA LIMITED
    Inventors: Dharmaraj Ramachandra Rao, Rajendra Narayanrao Kankan, Manjinder Singh Phull
  • Patent number: 8716476
    Abstract: A process for preparing alfuzosin or a salt thereof comprising: (a) condensing 4-amino-2-chloro-6,7-dimethoxyquinazoline with 3-methylaminopropionitrile in the presence of a polar aprotic solvent selected from the group consisting of diglyme, dimethyl formamide, t-butanol, hexamethylphosphoramide or mixtures thereof to form N-(4-amino-6,7-dimethoxyquinazol-2-yl)-N-methyl-2-cyanoethylamine (b) hydrogenating the N-(4-amino-6,7-dimethoxyquinazol-2-yl)-N-methyl-2-cyanoethylamine using a hydrogenating agent under a pressure of less than 10 kg/cm2 to form N-(4-amino-6,7-dimethoxyquinazol-2-yl)-N-methylpropylenediamine and optionally converting the N-(4-amino-6,7-dimethoxyquinazol-2-yl)-N-methylpropylenediamine to an acid addition salt thereof; and (c) converting tetrahydrofuroic acid to an intermediate form and condensing the intermediate form with the N-(4-amino-6,7-dimethoxyquinazol-2-yl)-N-methylpropylenediamine or with the acid addition salt to yield alfuzosin base, and optionally converting alfuzosin base to a
    Type: Grant
    Filed: August 1, 2008
    Date of Patent: May 6, 2014
    Assignee: Cipla Limited
    Inventors: Rajendra Narayanrao Kankan, Dharmaraj Ramachandra Rao, Dilip Birari