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Papers by Yogesh Sangvikar
Tetrahedron Letters, 2015
Abstract New pyromellitic diimide-based tetrabromo[2+2]macrocycle ([2+2]MC) 2, tribromo- and hexa... more Abstract New pyromellitic diimide-based tetrabromo[2+2]macrocycle ([2+2]MC) 2, tribromo- and hexabromo[3+3]MCs 3a and 3b, as well as triiodo[3+3]MC 3c were synthesized as structural units of covalently bound nanotubes, and their absorption spectra and redox properties, as well as inclusion phenomena of the [2+2]MC 2 were reported. Tetrabromo[2+2]MC 2 forms a 1:1 inclusion complex with toluene, whose structure was revealed by X-ray structural analysis.
La presente invention concerne une forme cristalline de carfilzomib M1 et un procede de preparati... more La presente invention concerne une forme cristalline de carfilzomib M1 et un procede de preparation associe. L'invention concerne egalement des procedes de preparation de carfilzomib amorphe utilisant la forme cristalline M1 comme matiere de depart. La presente invention concerne egalement un procede ameliore de preparation de carfilzomib.
![Research paper thumbnail of Dipyridyl/pyridinium thieno[2,3- b]thiophenes as new atropisomeric systems. Synthesis, conformational analysis and energy minimization](https://attachments.academia-assets.com/71934263/thumbnails/1.jpg)
](Tetrahedron, 2005
Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno[2,3-b]thiophenes wit... more Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno[2,3-b]thiophenes with or without-CO 2 Et and-COMe substituents at C2, and C5 positions of thieno[2,3-b]thiophene ring was readily accomplished using a double Dieckman cyclization protocol as the key step. While C2/C5 substituted dipyridylthieno[2,3-b]thiophenes exhibited syn/anti atropisomerism at least up to 70 8C with Arrhenius energy of activation (DG s) in the range of 17-18 kcal/mol, on the other hand unsubstituted dipyridylthieno[2,3-b]thiophene and its bis-N-quaternized salt were found to show free conformational rotation with an estimated DG s of lower than 10 kcal/mol. Conformational energy minimization using AM1 protocol revealed a slight preference for the anti over syn isomers. Compared to the unsubstituted dipyridylthieno[2,3-b]thiophenes, higher energy barriers to rotation (3.7-5.1 kcal/mol) in substituted dipyridylthieno[2,3-b]thiophenes can be attributed to steric encumbrance resulting from-CO 2 Et and-COMe substituents located on the non-rotating thienothiophene platform.
Cheminform, 2005
Abstract Synthesis of biaryl type systems, 11-aryl/heteroarylnaphtho [2, 1-b] furans 8-11 has bee... more Abstract Synthesis of biaryl type systems, 11-aryl/heteroarylnaphtho [2, 1-b] furans 8-11 has been described with a view to studying the conformational orientation of C-11 aryl/heteroaryl groups. Synthesis of 8-11 was accomplished by a two-step sequence involving O-...
![Research paper thumbnail of Synthesis and Structural Study of 3-Anisyl-4-(4?-pyridyl)(pyridinium)thieno[2,3-b]thienophenes](https://attachments.academia-assets.com/44110742/thumbnails/1.jpg)
](ChemInform, 2005
pyridinium)thieno[2,3-b]thienophenes. -Thienothiophene (VII) and its methylated derivative (IX) a... more pyridinium)thieno[2,3-b]thienophenes. -Thienothiophene (VII) and its methylated derivative (IX) are prepared and the presence of through-space or through bond charge transfer interaction is studied. -(MASHRAQUI*, S. H.; HARIHARASUBRAHMANIAN, H.; ASHRAF, M.; SANGVIKAR, Y.; Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem. 44 (2005) 1, 115-120; Dep. Chem., Univ. Mumbai, Vidyanagari, Mumbai 400 098, India; Eng.) -M. Bohle 19-153
![Research paper thumbnail of Oxa-bridged cyclophanes featuring thieno[2,3-b]thiophene and C2-symmetric binol or bis-naphthol rings: synthesis, structures, and conformational studies](https://attachments.academia-assets.com/44110740/thumbnails/1.jpg)
](Tetrahedron, 2008
Oxa-bridged cyclophanes 4/6 and 8/10 featuring thieno[2,3-b]thiophene ring and binol or bis-napht... more Oxa-bridged cyclophanes 4/6 and 8/10 featuring thieno[2,3-b]thiophene ring and binol or bis-naphthol have been synthesized. The structures are assigned by 2D NMR data and the identity of 4 is also independently established by a single X-ray crystallography. From dynamic NMR analysis, the Arrhenius energy of activation DG # for bridge inversions in 4 and 6 was calculated to be 15.3 and 12.9 kcal/mol, respectively. A higher DG # for 4, relative to the ester free 6 is attributable to the steric compression stemming from C2/C5 ester substituents to the bridge inversion processes. While the methylene bridges undergo inversion in 4 and 6, the naphthyl-naphthyl pseudo-rotation appears to be restricted even at higher temperatures. This is supported by retention of the optical purity of the chiral (À) 4 under thermal condition. For the case of bis-naphthol cyclophane 8, we observed the flipping of both the -OCH 2 -and the naphthyl-CH 2 -naphthyl bridges with DG # of ca. 11.4 kcal/mol. However, the ester free cyclophane 10 remained conformationally mobile even at À55 C and its DG # was assumed to be <11.4 kcal/mol. The presence of an extra -CH 2 -linker in bis-naphthol cyclophanes 8/10 renders them relatively more conformationally mobile compared to binol cyclophanes 4/6, possessing a rigid naphthyl-naphthyl geometry.
![Research paper thumbnail of Synthesis and structures of thieno[2,3-b]thiophene incorporated [3.3]dithiacyclophanes. Enhanced first hyperpolarizability in an unsymmetrically polarized cyclophane](https://attachments.academia-assets.com/44110743/thumbnails/1.jpg)
](Tetrahedron Letters, 2006
Dithiacyclophanes incorporating thieno[2,3-b]thiophene have been synthesized, in order to investi... more Dithiacyclophanes incorporating thieno[2,3-b]thiophene have been synthesized, in order to investigate the nonlinear optical properties of donor-acceptor cyclophane 7. Cyclophane 7 displayed significantly higher first hyperpolarizability b (21.6 · 10 À30 esu) compared to model 10 (9.58 · 10 À30 esu). Relatively higher b in 7 presumably arises from an extra electron redistribution arising from through-space charge transfer, a feature lacking in 10. Moreover, the thermal decomposition temperature of 7 (300°C) is higher than that reported for the NLO prototype DANS (295°C).
![Research paper thumbnail of Dipyridyl/pyridinium thieno[2,3-b]thiophenes as new atropisomeric systems. Synthesis, conformational analysis and energy minimization](https://attachments.academia-assets.com/44110741/thumbnails/1.jpg)
](Tetrahedron, 2005
Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno [2,3-b]thiophenes wi... more Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno [2,3-b]thiophenes with or without -CO 2 Et and -COMe substituents at C2, and C5 positions of thieno[2,3-b]thiophene ring was readily accomplished using a double Dieckman cyclization protocol as the key step. While C2/C5 substituted dipyridylthieno[2,3-b]thiophenes exhibited syn/anti atropisomerism at least up to 70 8C with Arrhenius energy of activation (DG s ) in the range of 17-18 kcal/mol, on the other hand unsubstituted dipyridylthieno[2,3-b]thiophene and its bis-N-quaternized salt were found to show free conformational rotation with an estimated DG s of lower than 10 kcal/mol. Conformational energy minimization using AM1 protocol revealed a slight preference for the anti over syn isomers. Compared to the unsubstituted dipyridylthieno[2,3-b]thiophenes, higher energy barriers to rotation (3.7-5.1 kcal/mol) in substituted dipyridylthieno[2,3-b]thiophenes can be attributed to steric encumbrance resulting from -CO 2 Et and -COMe substituents located on the non-rotating thienothiophene platform. q 2005 Elsevier Ltd. All rights reserved.
Organic Letters, 2009
Two straight monomers were subjected to an AA/BB-type Suzuki polycondensation with a hairpin-shap... more Two straight monomers were subjected to an AA/BB-type Suzuki polycondensation with a hairpin-shaped 1,8-anthrylene monomer as the counterpart leading to a novel polyarylene which should have the preferred conformation of a folded chain. The molar masses were determined by gel permeation chromatography and dynamic light scattering and found to be M(w) = 14,000 and M(n) = 7,000. MALDI-TOF MS analysis of a fraction provides a fingerprint of the step-growth nature of this polymerization.
Journal of Heterocyclic Chemistry, 2005
The biaryl structural motif is of fundamental importance to investigate atropisomerism [1]. The t... more The biaryl structural motif is of fundamental importance to investigate atropisomerism [1]. The torsional angle between the aryl-aryl bond is believed to play a key role in controlling photophysical and biological activities associ-ated with biaryl systems [2]. In this context, modern tech- ...
Tetrahedron Letters, 2015
Tetrahedron Letters, 2015
Abstract New pyromellitic diimide-based tetrabromo[2+2]macrocycle ([2+2]MC) 2, tribromo- and hexa... more Abstract New pyromellitic diimide-based tetrabromo[2+2]macrocycle ([2+2]MC) 2, tribromo- and hexabromo[3+3]MCs 3a and 3b, as well as triiodo[3+3]MC 3c were synthesized as structural units of covalently bound nanotubes, and their absorption spectra and redox properties, as well as inclusion phenomena of the [2+2]MC 2 were reported. Tetrabromo[2+2]MC 2 forms a 1:1 inclusion complex with toluene, whose structure was revealed by X-ray structural analysis.
La presente invention concerne une forme cristalline de carfilzomib M1 et un procede de preparati... more La presente invention concerne une forme cristalline de carfilzomib M1 et un procede de preparation associe. L'invention concerne egalement des procedes de preparation de carfilzomib amorphe utilisant la forme cristalline M1 comme matiere de depart. La presente invention concerne egalement un procede ameliore de preparation de carfilzomib.
Tetrahedron, 2005
Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno[2,3-b]thiophenes wit... more Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno[2,3-b]thiophenes with or without-CO 2 Et and-COMe substituents at C2, and C5 positions of thieno[2,3-b]thiophene ring was readily accomplished using a double Dieckman cyclization protocol as the key step. While C2/C5 substituted dipyridylthieno[2,3-b]thiophenes exhibited syn/anti atropisomerism at least up to 70 8C with Arrhenius energy of activation (DG s) in the range of 17-18 kcal/mol, on the other hand unsubstituted dipyridylthieno[2,3-b]thiophene and its bis-N-quaternized salt were found to show free conformational rotation with an estimated DG s of lower than 10 kcal/mol. Conformational energy minimization using AM1 protocol revealed a slight preference for the anti over syn isomers. Compared to the unsubstituted dipyridylthieno[2,3-b]thiophenes, higher energy barriers to rotation (3.7-5.1 kcal/mol) in substituted dipyridylthieno[2,3-b]thiophenes can be attributed to steric encumbrance resulting from-CO 2 Et and-COMe substituents located on the non-rotating thienothiophene platform.
Cheminform, 2005
Abstract Synthesis of biaryl type systems, 11-aryl/heteroarylnaphtho [2, 1-b] furans 8-11 has bee... more Abstract Synthesis of biaryl type systems, 11-aryl/heteroarylnaphtho [2, 1-b] furans 8-11 has been described with a view to studying the conformational orientation of C-11 aryl/heteroaryl groups. Synthesis of 8-11 was accomplished by a two-step sequence involving O-...
ChemInform, 2005
pyridinium)thieno[2,3-b]thienophenes. -Thienothiophene (VII) and its methylated derivative (IX) a... more pyridinium)thieno[2,3-b]thienophenes. -Thienothiophene (VII) and its methylated derivative (IX) are prepared and the presence of through-space or through bond charge transfer interaction is studied. -(MASHRAQUI*, S. H.; HARIHARASUBRAHMANIAN, H.; ASHRAF, M.; SANGVIKAR, Y.; Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem. 44 (2005) 1, 115-120; Dep. Chem., Univ. Mumbai, Vidyanagari, Mumbai 400 098, India; Eng.) -M. Bohle 19-153
Tetrahedron, 2008
Oxa-bridged cyclophanes 4/6 and 8/10 featuring thieno[2,3-b]thiophene ring and binol or bis-napht... more Oxa-bridged cyclophanes 4/6 and 8/10 featuring thieno[2,3-b]thiophene ring and binol or bis-naphthol have been synthesized. The structures are assigned by 2D NMR data and the identity of 4 is also independently established by a single X-ray crystallography. From dynamic NMR analysis, the Arrhenius energy of activation DG # for bridge inversions in 4 and 6 was calculated to be 15.3 and 12.9 kcal/mol, respectively. A higher DG # for 4, relative to the ester free 6 is attributable to the steric compression stemming from C2/C5 ester substituents to the bridge inversion processes. While the methylene bridges undergo inversion in 4 and 6, the naphthyl-naphthyl pseudo-rotation appears to be restricted even at higher temperatures. This is supported by retention of the optical purity of the chiral (À) 4 under thermal condition. For the case of bis-naphthol cyclophane 8, we observed the flipping of both the -OCH 2 -and the naphthyl-CH 2 -naphthyl bridges with DG # of ca. 11.4 kcal/mol. However, the ester free cyclophane 10 remained conformationally mobile even at À55 C and its DG # was assumed to be <11.4 kcal/mol. The presence of an extra -CH 2 -linker in bis-naphthol cyclophanes 8/10 renders them relatively more conformationally mobile compared to binol cyclophanes 4/6, possessing a rigid naphthyl-naphthyl geometry.
Tetrahedron Letters, 2006
Dithiacyclophanes incorporating thieno[2,3-b]thiophene have been synthesized, in order to investi... more Dithiacyclophanes incorporating thieno[2,3-b]thiophene have been synthesized, in order to investigate the nonlinear optical properties of donor-acceptor cyclophane 7. Cyclophane 7 displayed significantly higher first hyperpolarizability b (21.6 · 10 À30 esu) compared to model 10 (9.58 · 10 À30 esu). Relatively higher b in 7 presumably arises from an extra electron redistribution arising from through-space charge transfer, a feature lacking in 10. Moreover, the thermal decomposition temperature of 7 (300°C) is higher than that reported for the NLO prototype DANS (295°C).
Tetrahedron, 2005
Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno [2,3-b]thiophenes wi... more Synthesis of a new class of cofacially oriented dipyridyl(pyridinium)lthieno [2,3-b]thiophenes with or without -CO 2 Et and -COMe substituents at C2, and C5 positions of thieno[2,3-b]thiophene ring was readily accomplished using a double Dieckman cyclization protocol as the key step. While C2/C5 substituted dipyridylthieno[2,3-b]thiophenes exhibited syn/anti atropisomerism at least up to 70 8C with Arrhenius energy of activation (DG s ) in the range of 17-18 kcal/mol, on the other hand unsubstituted dipyridylthieno[2,3-b]thiophene and its bis-N-quaternized salt were found to show free conformational rotation with an estimated DG s of lower than 10 kcal/mol. Conformational energy minimization using AM1 protocol revealed a slight preference for the anti over syn isomers. Compared to the unsubstituted dipyridylthieno[2,3-b]thiophenes, higher energy barriers to rotation (3.7-5.1 kcal/mol) in substituted dipyridylthieno[2,3-b]thiophenes can be attributed to steric encumbrance resulting from -CO 2 Et and -COMe substituents located on the non-rotating thienothiophene platform. q 2005 Elsevier Ltd. All rights reserved.
Organic Letters, 2009
Two straight monomers were subjected to an AA/BB-type Suzuki polycondensation with a hairpin-shap... more Two straight monomers were subjected to an AA/BB-type Suzuki polycondensation with a hairpin-shaped 1,8-anthrylene monomer as the counterpart leading to a novel polyarylene which should have the preferred conformation of a folded chain. The molar masses were determined by gel permeation chromatography and dynamic light scattering and found to be M(w) = 14,000 and M(n) = 7,000. MALDI-TOF MS analysis of a fraction provides a fingerprint of the step-growth nature of this polymerization.
Journal of Heterocyclic Chemistry, 2005
The biaryl structural motif is of fundamental importance to investigate atropisomerism [1]. The t... more The biaryl structural motif is of fundamental importance to investigate atropisomerism [1]. The torsional angle between the aryl-aryl bond is believed to play a key role in controlling photophysical and biological activities associ-ated with biaryl systems [2]. In this context, modern tech- ...
Tetrahedron Letters, 2015