DR BRAJA SUNDAR PRADHAN
.Helvetica is founded by Dr Braja Sundar Pradhan in the year 2000. Dr Pradhan has synthetic organic chemistry background and completed doctoral studies under the supervision of renowned organic chemist, Professor Ian Flemming, University of Cambridge, United Kingdom.
The core area of strength of
the company is to design and develop non-infringing
synthetic routes to pharmaceutical and speciality
chemicals. Depending on the needs of its clients,
the company also undertakes manufacturing to provide
chemicals from kilogram to ton scale. Helvetica
is an export driven organization and exports high
quality speciality chemicals to Europe and the
USA.
Helvetica works in a partnership
with its clients to provide services and products
in a strictly confidential and exclusive manner
maintaining highest standard and total quality
assurances.
| Publication number | US20110263870 A1 |
| Publication type | Application |
| Application number | US 13/091,717 |
| Publication date | Oct 27, 2011 |
| Priority date | Apr 23, 2010 |
| Inventors | Braja Sundar Pradhan |
| Original Assignee | Helvetica Industries (P) Limited |
MYSELF WITH HIM IN CAMBRIDGE UK
Patent number: 8664417
Abstract: The invention
provides for a process for the preparation of a silylferrocene compound,
comprising the steps of treating ferrocene with a 4-chloroalkyryl
chloride in the presence of an lewis acid catalyst and an organic
solvent to obtain the acylated product, reducing the acylated product to
obtain the 4-chloralkylferrocene, treating the 4-chloroalkylferroce
with a metal under Grignard reaction conditions to form its
corresponding Grignard intermediate compound; and reacting with
chloroalkylsilane in-situ to give the silylferrocene compound. The
silylferrocene compound 4-(dimethylsilyl)butylferrocene can be prepared
by the process of the invention.
Type:
Grant
Filed:
October 18, 2010
Issued:
March 4, 2014
Assignee:
CBZ Chemicals Limited
Patent number: 8278468
Abstract: The invention
relates to a process for preparing furanose derivatives, to furanose
intermediates used in said process and to the use of said derivatives in
the manufacture of atorvastatin.
Type:
Grant
Filed:
September 23, 2011
Issued:
October 2, 2012
Assignee:
CBZ Chemicals Limited
Inventor:
Braja Sundar Pradhan
Example 1 1,2:5,6-Di-O-isopropylidene-3-O-(imidazole-1-sulfonyl)-α-D-glucofuranose (E1)
To a stirred solution of 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (250 g, 961.54 mmol) in anhydrous dichloromethane (3.59 lt), imidazole (440 g, 646 mmol) was added at 0 to −5° C. over a period of 0.5 h. The reaction mixture was stirred for 1 h at this temperature and then a solution of sulfuryl chloride (149 ml) in dichloromethane (20 ml) was added dropwise to the mixture. After 5 h at 0 to −5° C., the reaction mixture was allowed to warm to room temperature and stirred at this temperature until the reaction was complete as indicated by TLC.
The precipitated salt was filtered off and the filtrate was washed with water (3×1000 ml). The organic layer was then washed successively with 10% aqueous hydrochloric acid (10×1000 ml), water (1×1000 ml), saturated sodium bicarbonate solution (2×1000 ml), water (1×1000 ml) and finally with brine (2×1000 ml). The organic layer was dried over sodium sulphate and concentrated under reduced pressure to give the title product (E1) as a solid; yield: 320 g, 93%......http://www.google.com/patents/US8278468
Process for the synthesis of silylferrocene compounds
www.google.com/patents/EP2491049A1?cl=en
App. - Filed 18 Oct 2010 - Published 29 Aug 2012 - Braja Sundar Pradhan - CBZ Chemicals Limited
The invention provides for a process for the preparation of a silylferrocene compound, comprising the steps of treating ferrocene with a ...
Process for the synthesis of 4-(dimethylsilyl) butylferrocene
www.google.com/patents/US8664417
Grant - Filed 18 Oct 2010 - Issued 4 Mar 2014 - Braja Sundar Pradhan - Cbz Chemicals Limited
The invention provides for a process for the preparation of a silylferrocene compound, comprising the steps of treating ferrocene with a ...
Furanose derivatives for the preparation of atorvastatin
www.google.com/patents/EP2170916B1?cl=en
Grant - Filed 12 Jun 2008 - Issued 11 Jan 2012 - Braja Sundar Pradhan - Cbz Chemicals Limited
The invention relates to a process for preparing furanose derivatives, to furanose intermediates used in said process and to the use of said ...
Process for the synthesis of silylferrocene compounds
www.google.com/patents/WO2011048615A1?cl=en
App. - Filed 18 Oct 2010 - Published 28 Apr 2011 - Braja Sundar Pradhan - Cbz Chemicals Limited
The invention provides for a process for the preparation of a silylferrocene compound, comprising the steps of treating ferrocene with a ...
Furanose derivatives
www.google.com/patents/US8278468
Grant - Filed 23 Sep 2011 - Issued 2 Oct 2012 - Braja Sundar Pradhan - Cbz Chemicals Limited
The invention relates to a process for preparing furanose derivatives, to furanose intermediates used in said process and to the use of said ...
Furanose Derivatives
www.google.com/patents/EP2380895A1?cl=en
App. - Filed 12 Jun 2008 - Published 26 Oct 2011 - Braja Sundar Pradhan - Cbz Chemicals Limited
The invention relates to a process for preparing furanose derivatives, to furanose intermediates used in said process and to the use of said ...
Furanose derivatives
www.google.com/patents/US8115010
Grant - Filed 12 Jun 2008 - Issued 14 Feb 2012 - Braja Sundar Pradhan - Cbz Chemicals Limited
The invention relates to a process for preparing furanose derivatives, to furanose intermediates used in said process and to the use of said ...
Furanose derivatives and their applications in synthesis ...
www.google.co.in/patents/WO2012032534A3?cl=en
App. - Filed 8 Aug 2011 - Published 2 Aug 2012 - Thoomu Apparao - Helvetica Industries (P) Limited
The
present invention relates to compounds of formula XXII and their
synthesis from furanose derivatives as shown hereunder. Compounds of ...Process for preparing pregabalin
www.google.co.in/patents/WO2011016052A3?cl=en
App. - Filed 2 Aug 2010 - Published 31 Mar 2011 - B. S. Pradhan - Helvetica Industries (P) Limited
The invention relates to a process for preparing a compound of formula (I): wherein said process comprises hydrogenation of ...
Overview - Related - Discuss
The racemic pregabalin of Example 10 was filtered, washed with cold dichloromethane and resolved with (SJ-mandelic acid using isopropanol-water (97:3) solvent system following the procedure of Marvin S. Hoekstra et. al., Organic Process Research and Development, 1997, 1, 26, to obtain the first batch of pregabalin Another batch of pregabalin was obtained from the filtrates of the first resolution following the procedure as detailed under:
Example 11
(-)-3-Aminomethyl-5-methylhexanoic acid (E11)
The filtrates of the first resolution were combined and evaporated completely under reduced pressure to recover isopropyl alcohol, which was subsequently reused without any loss of either the purity or the yield of the final product, Pregabalin. The residue thus obtained was acidified with concentrated hydrochloric acid triggering the precipitation of the first batch of S(+)- Mandelic acid. The aqueous solution was then extracted with ethyl acetate. The organic layer was washed with water, brine, dried over sodium sulphate and evaporated under reduced pressure to give another batch of S(+)- Mandelic acid as a white solid which was combined with the former and recycled in subsequent batches without any loss of either the purity or the yield of the final product, Pregabalin. The aqueous layer containing the amino acid enriched with the undesired isomer was evaporated under reduced pressure to a thick oil and basified with triethyl amine at -5 0C to 0 0C. Chloroform was then added to it at -5 0C to 0 0C and the mixture was maintained at this temperature for 1-2 h. The precipitated solid was filtered, washed with cold chloroform and air-dried overnight to give the amino acid enriched with the undesired isomer which was resolved with R (-) Mandelic acid repeating the procedure of Marvin S. Hoekstra et. al., Organic Process Research and Development, 1997, 1, 26; to obtain the undesired isomer of pregabalin. The filtrates of this resolution was combined and evaporated under reduced pressure to recover and recycle isopropyl alcohol. The residue thus obtained was subjected to the process of recovery of R (-) Mandelic acid and the racemic Pregabalin following the protocol mentioned in the preceding paragraph. R (-) Mandelic acid was recycled in subsequent batches without any loss of the yield or the purity of the undesired isomer of Pregabalin. The recovered racemic Pregabalin thus obtained was again resolved with S(+)- Mandelic acid repeating the Marvin S. Hoekstra et. al., Organic Process Research and Development, 1997, 1, 26, to obtain a second batch of Pregabalin.......http://www.google.com/patents/WO2011016052A2?cl=en
Process for preparing pregabalin
www.google.co.in/patents/EP2462106A2?cl=en
App. - Filed 2 Aug 2010 - Published 13 Jun 2012 - B. S. Pradhan - Helvetica Industries (P) Limited
The
invention relates to a process for preparing a compound of formula (I):
wherein said process comprises hydrogenation of a compound of ...Novel pyrrole derivatives and their synthesis
www.google.co.in/patents/US20110263870
App. - Published 27 Oct 2011 - Braja Sundar Pradhan - Helvetica Industries (P) Limited
The present invention relates to two novel pyrrole derivatives ...Process for preparing pregabalin
www.google.co.in/patents/US20120142949
App. - Filed 2 Aug 2010 - Published 7 Jun 2012 - B. S. Pradhan - Helvetica Industries (P) Limited
The
invention relates to a process for preparing a compound of formula (I):
wherein said process comprises hydrogenation of a compound of ...Professor Ian Flemming, University of Cambridge, United Kingdom
Ian Fleming is an Emeritus Professor in the Department of Chemistry in the University of Cambridge, and an Emeritus Fellow of Pembroke College///////
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