Stefano Provera - Academia.edu (original) (raw)
Papers by Stefano Provera
Magnetic Resonance in Chemistry, 1997
1H and 13C NMR spectral data for several pyrido[2,3‐b]pyrazines and pyrido[2,3‐b]pyrazine‐N‐oxide... more 1H and 13C NMR spectral data for several pyrido[2,3‐b]pyrazines and pyrido[2,3‐b]pyrazine‐N‐oxides are reported. The chemical shift assignments were based on 1D‐NOE, gradient HSQC and gradient HMQC experiments for some model compounds. © 1997 by John Wiley & Sons, Ltd.
Tetrahedron Letters, 2002
A new synthesis of macrolactones bearing a cyclopropyl ring condensed to the macrocycle is report... more A new synthesis of macrolactones bearing a cyclopropyl ring condensed to the macrocycle is reported via a cyclization-release strategy making use of solid-phase supported stabilized sulfur ylides.
Methods and Principles in Medicinal Chemistry
Organic Process Research & Development, 2010
The family of phosphodiesterase (PDE) enzymes hydrolyse cyclic nucleotides, cAMP and cGMP, leadin... more The family of phosphodiesterase (PDE) enzymes hydrolyse cyclic nucleotides, cAMP and cGMP, leading to their inactivation as intracellular second messengers. Inhibition of these enzymes leads to an elevation of levels of cyclic nucleotides in the cell and prolongs their action on downstream signaling pathways. PDE4, of which there are four subtypes, is widely expressed throughout the brain but is also abundant in the periphery in inflammatory and immune cells, in the gastrointestinal tract, and in cardiac myocytes. GSK356278 1 is a potent, selective, and competitive inhibitor of PDE4 enzymes currently under investigation for the treatment of CNS disorders. The initial synthetic route developed by Medicinal Chemistry Department, used several hazardous and/or expensive reagents and harsh conditions and gave relatively low yields. By targeted process of research and development plus application of analytical techniques to identify byproduct and extensive route scouting, a novel synthetic route for 1 has been developed. This contribution reports the optimisation of the chemical synthesis of 1 to develop a large-scale process suitable for its synthesis.
Organic Process Research & Development, 2010
Process development towards the improvement of the manufacturing process of casopitant mesylate (... more Process development towards the improvement of the manufacturing process of casopitant mesylate (a drug developed by GlaxoSmithKline with activity on the central nervous system) identified a dynamic kinetic resolution opportunity for the improvement of the yield. In this paper, the application of quality by design principles to the DKR is presented together with the issues that were faced during different scale-ups and the at-scale solutions that were implemented.
![Research paper thumbnail of An Efficient Scalable Route for the Synthesis of Enantiomerically Pure tert -Butyl-(1 R ,4 S ,6 R )-4-(hydroxymethyl)-3-azabicyclo[4.1.0]heptane-3-carboxylate](https://attachments.academia-assets.com/86839738/thumbnails/1.jpg)
](Organic Process Research & Development, 2010
An efficient scalable route to synthesize the enantiomerically pure tert-butyl-(1R,4S,6R)-4-(hydr... more An efficient scalable route to synthesize the enantiomerically pure tert-butyl-(1R,4S,6R)-4-(hydroxymethyl)-3-azabicyclo[4.1.0]heptane-3-carboxylate is described. Compared to the original routes, significant improvements were made by using an innovative approach starting from commercially available chiral lactone. In this approach, one of the key steps described is an elegant epimerization/hydrolysis of the undesired diastereoisomer avoiding tedious purification. The chemistry has been scaled up to produce kilogram amounts of tert-butyl-(1R,4S,6R)-4-(hydroxymethyl)-3azabicyclo[4.1.0]heptane-3-carboxylate in 43% yield over nine chemical transformations.
Organic Process Research & Development, 2010
Casopitant was identified as a potent NK1 antagonist by GlaxoSmithKline (GSK). It was selected as... more Casopitant was identified as a potent NK1 antagonist by GlaxoSmithKline (GSK). It was selected as part of a wide drug discovery programme within GSK for its potential activities on a number of therapeutic targets such as inflammatory bowel disease, overactive bladder, CNS disorders, and others. The mesylate salt of casopitant was selected for full development. The manufacturing process to casopitant mesylate was developed and optimised by following a Quality by Design approach, whereby a control strategy was developed, underpinned by process understanding and risk analysis, for an enhanced level of quality assurance. Quality process parameters and specifications levels for the Stages 2a, 2b, and 2c are the elements of the control strategy of the manufacturing process discussed in detail in this paper. The Design of Experiment approach has been extensively used to support the definition of the proven acceptable ranges for the process. The aim is to show the process development studies carried out to ensure...
![Research paper thumbnail of Identification of a Manufacturing Route of Novel CRF-1 Antagonists Containing a 2,3-Dihydro-1 H -pyrrolo[2,3- b ]pyridine Moiety](https://attachments.academia-assets.com/86839736/thumbnails/1.jpg)
](Organic Process Research & Development, 2010
A case study on the synthesis of novel CRF-1 antagonists containing the 2,3-dihydro-1H-pyrrolo[2,... more A case study on the synthesis of novel CRF-1 antagonists containing the 2,3-dihydro-1H-pyrrolo[2,3-b]pyridine moiety is presented. The development of ever more efficient synthetic routes allowed the progression of three candidates at the same time. A manufacturing route was identified and successfully demonstrated on a pilot-plant scale to prepare 100 kg of the CRF-1 antagonist GW876008.
Organic Process Research & Development, 2010
GV143253A 1 is a broad-spectrum injectable-lactam belonging to the class of trinem antibiotics. T... more GV143253A 1 is a broad-spectrum injectable-lactam belonging to the class of trinem antibiotics. This article describes the work which enabled a detailed process understanding via several analytical techniques and the subsequent optimization of a key intermediate. By means of a combined application of 31 P NMR spectroscopy and MS spectrometry, the main impurities have been identified and the reaction mechanisms clarified. Moreover, a design of experiments (DoE) approach was applied which substantially improved the overall yield.
Tetrahedron Letters, 1999
A series of polymer-bound Fischer chromium alkoxy and amino carbene type I complexes were synthes... more A series of polymer-bound Fischer chromium alkoxy and amino carbene type I complexes were synthesized by the thermal exchange of a CO ligand in chromium pentacarbonyl earbenes 2 with triphenyl phosphine resin 1. The supported alkoxyearbene 3a proved to be reactive towards primary amines, and afforded the polymer-bound aminocarbenes 5. Type II aminocarbenes were also prepared by reacting polymer-supported aminoaeids with alkoxycarbene 2a.
Tetrahedron Letters, 2000
... Opin. Chem. Biol. 1998, 2, 353–368. Kingsbury, CL; Mehrman, SJ; Takas, JM Current Organic Che... more ... Opin. Chem. Biol. 1998, 2, 353–368. Kingsbury, CL; Mehrman, SJ; Takas, JM Current Organic Chemistry 1999, 3, 497–555. 2. Lorsbach, BA; Kurth, M. Chem. Rev. 1999, 99, 1549–1581. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (207). ...
Tetrahedron Letters, 2010
ABSTRACT An uncommon reactivity of 2-fluoro-4-(trifluoromethyl)-phenylacetonitrile, with the loss... more ABSTRACT An uncommon reactivity of 2-fluoro-4-(trifluoromethyl)-phenylacetonitrile, with the loss of three fluorine atoms, is herein reported, the resulting trimeric compound was isolated and characterized by NMR and MS/MS studies. An unprecedented mechanism has been proposed.
Physiologia Plantarum, 2005
In this paper, we report the metabolic and molecular changes in response to cold and drought indu... more In this paper, we report the metabolic and molecular changes in response to cold and drought induced in Osmyb4 transgenic Arabidopsis thaliana compared with the wildtype (WT). The rice Osmyb4 gene codes for a transcription factor (Myb4) induced by cold treatment and, in Arabidopsis transgenic plants, improves cold and freezing tolerance [Vannini C
Magnetic Resonance in Chemistry, 2010
Liquid chromatography (LC)-NMR spectroscopy was used to obtain detailed information regarding the... more Liquid chromatography (LC)-NMR spectroscopy was used to obtain detailed information regarding the structure of a bulk drug impurity present in glycinamide ribonucleotide transformylase (GART) inhibitor AG2034. The LC-NMR experiments (1D 1 H and 2D TOCSY) were performed in the stop-flow mode on crude retained impurityenriched samples of the synthetic precursor to AG2034. Comparative analysis of the data for the parent compound with those for the impurity indicated that the impurity was nearly a dimer of the parent, and allowed all major substructures to be delineated. The structural information derived from both LC-NMR and LC-MS data provided insights into purification methods, which ultimately led to the full characterization of the impurity by high-resolution NMR spectroscopy.
Magnetic Resonance in Chemistry, 2010
We have developed QUANTAS (QUANTification by Artificial Signal), which is a software-based protoc... more We have developed QUANTAS (QUANTification by Artificial Signal), which is a software-based protocol for concentration measurement by NMR. QUANTAS is an absolute intensity external standard method for quantification by NMR that compensates for various experimental parameters. It is applicable to all nuclei and modern spectrometers. QUANTAS is demonstrated here for 1 H and 19 F NMR, enabling heteronuclear integrals to be compared. It can be applied using fixed probe tuning, matching and pulse length, for samples with the same effective loading on the probe coil as the appropriate reference spectrum. Otherwise, an optimised tuning and matching approach is adopted for every sample together with explicit PULCON (PUlse Length-based CONcentration measurements) absolute intensity corrections.
Journal of Pharmaceutical and Biomedical Analysis, 2010
A multi-technique approach was applied in order to fully characterize four low-level unknown impu... more A multi-technique approach was applied in order to fully characterize four low-level unknown impurities of GW876008, a novel CRF 1 receptor antagonist. Liquid chromatography (LC)-NMR spectroscopy was used in combination with LC-MS to obtain detailed information regarding the structure of the two major impurities present in batches of GW876008 and observed in the first synthetic scale-up for preclinical use. Two additional impurities were unexpectedly found at greater levels in a large scale synthesis for clinical use and their structure was elucidated by means of high resolution (HR)-MS and HR-NMR, after a small scale preparative HPLC purification step. This structural information was useful in terms of shedding light on the typical impurity profile of this new chemical entity with the aim to support the early development package for Phase I clinical studies.
Journal of Pharmaceutical and Biomedical Analysis, 2010
Vestipitant (1) is a novel NK1 antagonist currently under investigation for the treatment of CNS ... more Vestipitant (1) is a novel NK1 antagonist currently under investigation for the treatment of CNS disorders and emesis. The first synthetic step comprised a Grignard synthesis. An impurity was identified and initially expected to be a symmetric biphenyl. This paper reports the work to synthesise the supposed structure and the spectroscopic analyses (LC-NMR and HR-NMR) to correctly identify the real structure and understand the chemical pathway of the impurity.
Journal of Pharmaceutical and Biomedical Analysis, 2011
The aggregation behaviour of casopitant mesylate, a new NK1 antagonist drug, was investigated by ... more The aggregation behaviour of casopitant mesylate, a new NK1 antagonist drug, was investigated by means of NMR spectroscopy and surface tension measurements. The critical micelle concentration (CMC) in glycine buffer at pH 3.5 was determined by analyzing the (1)H NMR chemical shifts variation and the surface tension in function of the concentration in a series of solutions. The temperature dependence of the CMC was also evaluated by NMR spectroscopy as well as the thermodynamic parameters contributing to the aggregation discussed. Surface tension measurements were conducted as well in the formulation conditions, e.g. in the presence of sodium chloride.
Magnetic Resonance in Chemistry, 1997
1H and 13C NMR spectral data for several pyrido[2,3‐b]pyrazines and pyrido[2,3‐b]pyrazine‐N‐oxide... more 1H and 13C NMR spectral data for several pyrido[2,3‐b]pyrazines and pyrido[2,3‐b]pyrazine‐N‐oxides are reported. The chemical shift assignments were based on 1D‐NOE, gradient HSQC and gradient HMQC experiments for some model compounds. © 1997 by John Wiley & Sons, Ltd.
Tetrahedron Letters, 2002
A new synthesis of macrolactones bearing a cyclopropyl ring condensed to the macrocycle is report... more A new synthesis of macrolactones bearing a cyclopropyl ring condensed to the macrocycle is reported via a cyclization-release strategy making use of solid-phase supported stabilized sulfur ylides.
Methods and Principles in Medicinal Chemistry
Organic Process Research & Development, 2010
The family of phosphodiesterase (PDE) enzymes hydrolyse cyclic nucleotides, cAMP and cGMP, leadin... more The family of phosphodiesterase (PDE) enzymes hydrolyse cyclic nucleotides, cAMP and cGMP, leading to their inactivation as intracellular second messengers. Inhibition of these enzymes leads to an elevation of levels of cyclic nucleotides in the cell and prolongs their action on downstream signaling pathways. PDE4, of which there are four subtypes, is widely expressed throughout the brain but is also abundant in the periphery in inflammatory and immune cells, in the gastrointestinal tract, and in cardiac myocytes. GSK356278 1 is a potent, selective, and competitive inhibitor of PDE4 enzymes currently under investigation for the treatment of CNS disorders. The initial synthetic route developed by Medicinal Chemistry Department, used several hazardous and/or expensive reagents and harsh conditions and gave relatively low yields. By targeted process of research and development plus application of analytical techniques to identify byproduct and extensive route scouting, a novel synthetic route for 1 has been developed. This contribution reports the optimisation of the chemical synthesis of 1 to develop a large-scale process suitable for its synthesis.
Organic Process Research & Development, 2010
Process development towards the improvement of the manufacturing process of casopitant mesylate (... more Process development towards the improvement of the manufacturing process of casopitant mesylate (a drug developed by GlaxoSmithKline with activity on the central nervous system) identified a dynamic kinetic resolution opportunity for the improvement of the yield. In this paper, the application of quality by design principles to the DKR is presented together with the issues that were faced during different scale-ups and the at-scale solutions that were implemented.
Organic Process Research & Development, 2010
An efficient scalable route to synthesize the enantiomerically pure tert-butyl-(1R,4S,6R)-4-(hydr... more An efficient scalable route to synthesize the enantiomerically pure tert-butyl-(1R,4S,6R)-4-(hydroxymethyl)-3-azabicyclo[4.1.0]heptane-3-carboxylate is described. Compared to the original routes, significant improvements were made by using an innovative approach starting from commercially available chiral lactone. In this approach, one of the key steps described is an elegant epimerization/hydrolysis of the undesired diastereoisomer avoiding tedious purification. The chemistry has been scaled up to produce kilogram amounts of tert-butyl-(1R,4S,6R)-4-(hydroxymethyl)-3azabicyclo[4.1.0]heptane-3-carboxylate in 43% yield over nine chemical transformations.
Organic Process Research & Development, 2010
Casopitant was identified as a potent NK1 antagonist by GlaxoSmithKline (GSK). It was selected as... more Casopitant was identified as a potent NK1 antagonist by GlaxoSmithKline (GSK). It was selected as part of a wide drug discovery programme within GSK for its potential activities on a number of therapeutic targets such as inflammatory bowel disease, overactive bladder, CNS disorders, and others. The mesylate salt of casopitant was selected for full development. The manufacturing process to casopitant mesylate was developed and optimised by following a Quality by Design approach, whereby a control strategy was developed, underpinned by process understanding and risk analysis, for an enhanced level of quality assurance. Quality process parameters and specifications levels for the Stages 2a, 2b, and 2c are the elements of the control strategy of the manufacturing process discussed in detail in this paper. The Design of Experiment approach has been extensively used to support the definition of the proven acceptable ranges for the process. The aim is to show the process development studies carried out to ensure...
Organic Process Research & Development, 2010
A case study on the synthesis of novel CRF-1 antagonists containing the 2,3-dihydro-1H-pyrrolo[2,... more A case study on the synthesis of novel CRF-1 antagonists containing the 2,3-dihydro-1H-pyrrolo[2,3-b]pyridine moiety is presented. The development of ever more efficient synthetic routes allowed the progression of three candidates at the same time. A manufacturing route was identified and successfully demonstrated on a pilot-plant scale to prepare 100 kg of the CRF-1 antagonist GW876008.
Organic Process Research & Development, 2010
GV143253A 1 is a broad-spectrum injectable-lactam belonging to the class of trinem antibiotics. T... more GV143253A 1 is a broad-spectrum injectable-lactam belonging to the class of trinem antibiotics. This article describes the work which enabled a detailed process understanding via several analytical techniques and the subsequent optimization of a key intermediate. By means of a combined application of 31 P NMR spectroscopy and MS spectrometry, the main impurities have been identified and the reaction mechanisms clarified. Moreover, a design of experiments (DoE) approach was applied which substantially improved the overall yield.
Tetrahedron Letters, 1999
A series of polymer-bound Fischer chromium alkoxy and amino carbene type I complexes were synthes... more A series of polymer-bound Fischer chromium alkoxy and amino carbene type I complexes were synthesized by the thermal exchange of a CO ligand in chromium pentacarbonyl earbenes 2 with triphenyl phosphine resin 1. The supported alkoxyearbene 3a proved to be reactive towards primary amines, and afforded the polymer-bound aminocarbenes 5. Type II aminocarbenes were also prepared by reacting polymer-supported aminoaeids with alkoxycarbene 2a.
Tetrahedron Letters, 2000
... Opin. Chem. Biol. 1998, 2, 353–368. Kingsbury, CL; Mehrman, SJ; Takas, JM Current Organic Che... more ... Opin. Chem. Biol. 1998, 2, 353–368. Kingsbury, CL; Mehrman, SJ; Takas, JM Current Organic Chemistry 1999, 3, 497–555. 2. Lorsbach, BA; Kurth, M. Chem. Rev. 1999, 99, 1549–1581. Full Text via CrossRef | View Record in Scopus | Cited By in Scopus (207). ...
Tetrahedron Letters, 2010
ABSTRACT An uncommon reactivity of 2-fluoro-4-(trifluoromethyl)-phenylacetonitrile, with the loss... more ABSTRACT An uncommon reactivity of 2-fluoro-4-(trifluoromethyl)-phenylacetonitrile, with the loss of three fluorine atoms, is herein reported, the resulting trimeric compound was isolated and characterized by NMR and MS/MS studies. An unprecedented mechanism has been proposed.
Physiologia Plantarum, 2005
In this paper, we report the metabolic and molecular changes in response to cold and drought indu... more In this paper, we report the metabolic and molecular changes in response to cold and drought induced in Osmyb4 transgenic Arabidopsis thaliana compared with the wildtype (WT). The rice Osmyb4 gene codes for a transcription factor (Myb4) induced by cold treatment and, in Arabidopsis transgenic plants, improves cold and freezing tolerance [Vannini C
Magnetic Resonance in Chemistry, 2010
Liquid chromatography (LC)-NMR spectroscopy was used to obtain detailed information regarding the... more Liquid chromatography (LC)-NMR spectroscopy was used to obtain detailed information regarding the structure of a bulk drug impurity present in glycinamide ribonucleotide transformylase (GART) inhibitor AG2034. The LC-NMR experiments (1D 1 H and 2D TOCSY) were performed in the stop-flow mode on crude retained impurityenriched samples of the synthetic precursor to AG2034. Comparative analysis of the data for the parent compound with those for the impurity indicated that the impurity was nearly a dimer of the parent, and allowed all major substructures to be delineated. The structural information derived from both LC-NMR and LC-MS data provided insights into purification methods, which ultimately led to the full characterization of the impurity by high-resolution NMR spectroscopy.
Magnetic Resonance in Chemistry, 2010
We have developed QUANTAS (QUANTification by Artificial Signal), which is a software-based protoc... more We have developed QUANTAS (QUANTification by Artificial Signal), which is a software-based protocol for concentration measurement by NMR. QUANTAS is an absolute intensity external standard method for quantification by NMR that compensates for various experimental parameters. It is applicable to all nuclei and modern spectrometers. QUANTAS is demonstrated here for 1 H and 19 F NMR, enabling heteronuclear integrals to be compared. It can be applied using fixed probe tuning, matching and pulse length, for samples with the same effective loading on the probe coil as the appropriate reference spectrum. Otherwise, an optimised tuning and matching approach is adopted for every sample together with explicit PULCON (PUlse Length-based CONcentration measurements) absolute intensity corrections.
Journal of Pharmaceutical and Biomedical Analysis, 2010
A multi-technique approach was applied in order to fully characterize four low-level unknown impu... more A multi-technique approach was applied in order to fully characterize four low-level unknown impurities of GW876008, a novel CRF 1 receptor antagonist. Liquid chromatography (LC)-NMR spectroscopy was used in combination with LC-MS to obtain detailed information regarding the structure of the two major impurities present in batches of GW876008 and observed in the first synthetic scale-up for preclinical use. Two additional impurities were unexpectedly found at greater levels in a large scale synthesis for clinical use and their structure was elucidated by means of high resolution (HR)-MS and HR-NMR, after a small scale preparative HPLC purification step. This structural information was useful in terms of shedding light on the typical impurity profile of this new chemical entity with the aim to support the early development package for Phase I clinical studies.
Journal of Pharmaceutical and Biomedical Analysis, 2010
Vestipitant (1) is a novel NK1 antagonist currently under investigation for the treatment of CNS ... more Vestipitant (1) is a novel NK1 antagonist currently under investigation for the treatment of CNS disorders and emesis. The first synthetic step comprised a Grignard synthesis. An impurity was identified and initially expected to be a symmetric biphenyl. This paper reports the work to synthesise the supposed structure and the spectroscopic analyses (LC-NMR and HR-NMR) to correctly identify the real structure and understand the chemical pathway of the impurity.
Journal of Pharmaceutical and Biomedical Analysis, 2011
The aggregation behaviour of casopitant mesylate, a new NK1 antagonist drug, was investigated by ... more The aggregation behaviour of casopitant mesylate, a new NK1 antagonist drug, was investigated by means of NMR spectroscopy and surface tension measurements. The critical micelle concentration (CMC) in glycine buffer at pH 3.5 was determined by analyzing the (1)H NMR chemical shifts variation and the surface tension in function of the concentration in a series of solutions. The temperature dependence of the CMC was also evaluated by NMR spectroscopy as well as the thermodynamic parameters contributing to the aggregation discussed. Surface tension measurements were conducted as well in the formulation conditions, e.g. in the presence of sodium chloride.