Biswanath Das - Academia.edu (original) (raw)
Papers by Biswanath Das
Tetrahedron Letters, 2006
An efficient Zn/AlCl 3 promoted highly regioselective one-pot procedure has been demonstrated for... more An efficient Zn/AlCl 3 promoted highly regioselective one-pot procedure has been demonstrated for the synthesis of β-amino selenides and -sulfides from variety of diselenides/disulfides and aziridines by reductive cleavage of Se-Se and S-S bonds using Zn/AlCl 3 system in acetonitrile under very mild conditions.
Journal of Chemical Research-s, 2003
... using ceric ammonium nitrate: A novel and efficient method for the synthesis of di-and tri-in... more ... using ceric ammonium nitrate: A novel and efficient method for the synthesis of di-and tri-indolylmethanes1, C. Ramesh, N. Ravindranath and Biswanath Das* Organic ... 1961, 26, 4241; (b) A. Chatterjee, S. Manna, J. Banerji, C. Pascard, T. Prange and JN Shoolery; J. Chem. ...
![Research paper thumbnail of Iodine catalyzed simple and efficient synthesis of 14-aryl or alkyl-14- H-dibenzo[ a, j]xanthenes](https://attachments.academia-assets.com/47897056/thumbnails/1.jpg)
](Journal of Molecular Catalysis A-chemical, 2006
A simple and facile synthesis of 14-aryl or alkyl-14-H-dibenzo [a,j]xanthenes has been accomplish... more A simple and facile synthesis of 14-aryl or alkyl-14-H-dibenzo [a,j]xanthenes has been accomplished by treatment of 2-naphthol with aryl or alkyl aldehydes under neat conditions in the presence of molecular iodine as a catalyst. H NMR (200 MHz, CDCl 3 ): δ 8.34 (2H, d, J = 8.0 Hz), 7.88-7.72 (4H, m), 7.60-7.32 (8H, m), 6.93 (2H, d, J = 8.0 Hz), 6.42 (1H, s), 2.42 (2H, q, J = 7.0 Hz), 1.04 (3H, t, J = 7.0 Hz); EIMS: m/z 386 (M • + ) Compound 3d-IR (KBr): 3428, 1632, 1560, 1475, 1229 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.13 (2H, d, J = 8.0 Hz), 7.82-7.68 (4H, m), 7.56-7.30 (8H, m), 6.55 (2H, d, J = 8.0 Hz), 6.38 (1H, s), 4.32 (1H, brs); EIMS: m/z 374 (M • + ). Compound 3f-IR (KBr): 1621, 1592, 1515, 1398, 1244 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.27 (1H, d, J = 8.0 Hz), 7.84-7.75 (4H, m), 7.62-7.33 (9H, m), 7.28-7.15 (2H, m), 6.50 (1H, m); EIMS: m/z 426 (M • + ). Compound 3g-IR (KBr): 1629, 1525, 1475, 1288 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.37 (2H, d, J = 8.0 Hz), 7.82-7.75 (4H, m), 7.59-7.52 (2H, m), 7.48-7.37 (4H, m), 7.12 (1H, dd, J = 8.0, 2.0 Hz), 6.78 (1H, d, J = 2.0 Hz), 6.70 (1H, d, J = 2.0 Hz), 6.38 (1H, s), 5.28 (1H, s), 3.63 (3H, s); EIMS: m/z 404 (M • + ). Compound 3m-IR (CHCl 3 ): 1622, 1591, 1515, 1457, 1240 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.26 (2H, d, J = 8.0 Hz), 7.90-7.72 (4H, m), 7.61-7.49 (2H, m), 7.43-7.32 (4H, m), 5.42 (1H, d, J = 7.0 Hz), 2.28 (1H, m), 0.81 (6H, d, J = 7.0 Hz); EIMS: m/z 324 (M • + ).
Tetrahedron Letters, 2005
a-Bromination of carbonyl compounds (cyclic and acyclic ketones, amides and b-ketoesters) has bee... more a-Bromination of carbonyl compounds (cyclic and acyclic ketones, amides and b-ketoesters) has been achieved efficiently by treatment with N-bromosuccinimide (NBS) and catalyzed by silica-supported sodium hydrogen sulfate (NaHSO 4 AESiO 2 ). The products were formed in high yields under mild reaction conditions and in short reaction times.
Tetrahedron Letters, 2008
A series of anilines were converted into the corresponding N-formyl amines in high yields followi... more A series of anilines were converted into the corresponding N-formyl amines in high yields following the above procedure (Table 1). No additional solvent or catalyst was used. Different functionalities such as alkyl, nitro, halogens and carbonyl remained intact. Anilines containing both ...
Synlett, 2007
... 2a Chetia A, Saikia CJ, Lekhok KC, Boruah RC,Tetrahedron Lett. 2004, 45: 2649. 2b Devi I, Bhu... more ... 2a Chetia A, Saikia CJ, Lekhok KC, Boruah RC,Tetrahedron Lett. 2004, 45: 2649. 2b Devi I, Bhuyan PJ,Tetrahedron Lett. 2004, 45: 8625. ... Catal. A: Chem. 2007, 261: 180. 19a Ramesh C, Ravindranath N, Das B,J. Org. Chem. 2003, 68: 7101. ...
Synlett, 2006
... 2001, 66: 7527. 5b Ramalinga K, Vijayalakshmi P, Kaimal TNB,Tetrahedron Lett. 2002, 43: 879. ... more ... 2001, 66: 7527. 5b Ramalinga K, Vijayalakshmi P, Kaimal TNB,Tetrahedron Lett. 2002, 43: 879. 5c Yadav JS, Reddy BVS, Reddy MS, Prasad AR,Tetrahedron Lett. 2002, 43: 9703. 5d Das B, Banerrjee J, Ramu R, Ravindranath N, Ramesh C,Tetrahedron Lett. 2003, 44: 5465. ...
Tetrahedron Letters, 2007
Benzimidazoles have been efficiently synthesized in high yields by treatment of 1,2-phenylenediam... more Benzimidazoles have been efficiently synthesized in high yields by treatment of 1,2-phenylenediamine with aldehydes using (bromodimethyl)sulfonium bromide at room temperature.
Tetrahedron Letters, 2004
Treatment of aldoximes with activated alkenes in the presence of diacetoxy iodobenzene (DIB) affo... more Treatment of aldoximes with activated alkenes in the presence of diacetoxy iodobenzene (DIB) afforded isoxazolines in high yields. The method has been applied for the preparation of polyfunctional isoxazolines from Baylis-Hillman adducts.
Tetrahedron, 1999
The naturally occurring alkaloids, camptothecin and mappicine ketone were converted to racemic ma... more The naturally occurring alkaloids, camptothecin and mappicine ketone were converted to racemic mappicine acetate which was enantioselectively hydrolyzed to (S)-and (R)-mappicines in high optical purity using baker's yeast and a lipase, Amano PS. Treatment of the racemic acetate with baker's yeast afforded (S)-mappicine while with Amano PS yielded (R)-mappicine. 9-Methoxycamptothecin and 9-methoxymappicine ketone underwent similar conversion to (S)-and (R)-9-methxymappicines.
Journal of Molecular Catalysis A-chemical, 2006
The aza-Michael reactions of amines with ␣,-unsaturated carbonyl and nitrile compounds have effi... more The aza-Michael reactions of amines with ␣,-unsaturated carbonyl and nitrile compounds have efficiently been carried out at room temperature using Amberlyst-15 as a heterogeneous reusable catalyst. The products were formed in short reaction times and in high yields.
Tetrahedron, 2004
The reaction involving the coupling of activated vinylic systems with electrophiles under the cat... more The reaction involving the coupling of activated vinylic systems with electrophiles under the catalytic influence of a tertiary amine (usually DABCO), known as the BaylisHillman reaction, is a useful carbon carbon bond forming method in synthetic organic chemistry. 1 The BaylisHillman ...
Tetrahedron Letters, 2003
Protection of carboxylic acids and subsequent deprotection have been used in multi-step transform... more Protection of carboxylic acids and subsequent deprotection have been used in multi-step transformations and syntheses of several bioactive naturally occurring molecules. [2.] , [3] and [4] Carboxylic acids are frequently protected as esters and unsaturated esters are particularly preferred ...
Pharmaceutical Biology, 2001
This study describes the antibacterial activity of the pure isolates from Piper longum (L.)(black... more This study describes the antibacterial activity of the pure isolates from Piper longum (L.)(black pepper) and Taxus baccata (L.)(Yew). Three isolates of black pepper were active against Gram-positive bacteria and moderately active against Gram-negative bacteria. ...
Organic Letters, 2004
[reaction: see text] Treatment of the acetyl derivatives of the Baylis-Hillman adducts 3-hydroxy-... more [reaction: see text] Treatment of the acetyl derivatives of the Baylis-Hillman adducts 3-hydroxy-2-methylene-alkanoates and 3-hydroxy-2-methylene-alkanenitriles with unactivated alkyl halides in the presence of Zn in saturated aqueous NH(4)Cl solution at room temperature afforded (2E)-2-substituted-alk-2-enoates in the first case and (2Z)-2-substituted-alk-2-enenitriles with high (Z)-selectivity in the second case.
Tetrahedron Letters, 2004
The stereoselective synthesis of (2Z)-2-(chloromethyl)alk-2-enoates has been achieved efficiently... more The stereoselective synthesis of (2Z)-2-(chloromethyl)alk-2-enoates has been achieved efficiently and in high yields and in short reaction times from Baylis-Hillman adducts, 3-hydroxy-2-methylene-alkanoates, by treatment with FeCl 3 or InCl 3 at room temperature.
Tetrahedron Letters, 1998
Two simple and efficient methods for the conversion of the naturally occurring alkaloid, camptoth... more Two simple and efficient methods for the conversion of the naturally occurring alkaloid, camptothecin to mappicine ketone, an antiviral lead compound, have been described. The first method involved the treatment of camptothecin with borontrifluoride etherate and the second method utilised the microwave irradiation of the alkaloid.
Phytochemistry, 2003
Two new pseudoguaianolide-type sesquiterpene lactones, named deacetyltetraneurin A (3) and hyster... more Two new pseudoguaianolide-type sesquiterpene lactones, named deacetyltetraneurin A (3) and hysterone E (4), were isolated from flowers of the plant Parthenium hysterophorus L., along with the seven known compounds parthenin (1), coronopilin, tetraneurin A, 8-b-hydroxycoronopilin, scopoletin, hysterone D, and conchasin A (2). The structures of all the compounds were deduced by means of elemental analysis and extensive spectroscopic (1D and 2D NMR) studies, and confirmed for 3 and 4 by X-ray crystallographic analysis.
Phytochemistry, 2003
Two new flavanoids, 5,7-dimethoxy-3 0 ,4 0 -methylenedioxyflavanone and isobonducellin along with... more Two new flavanoids, 5,7-dimethoxy-3 0 ,4 0 -methylenedioxyflavanone and isobonducellin along with 2 0 -hydroxy-2,3,4 0 ,6 0 -tetramethoxychalcone, 5,7-dimethoxyflavone and bonducellin were isolated from the aerial parts of Caesalpinia pulcherrima. The structures of the compounds were settled mainly by interpretation of their 1D and 2D NMR spectra. Isobonducellin was found to be a homoisoflavanoid containing a cis (Z)-double bond. Antimicrobial activity of the new compounds was evaluated. # Phytochemistry 63 (2003) 789-793 www.elsevier.com/locate/phytochem § Part 41 in the series, ''Studies on Phytochemicals''. Dedicated with regards to Professor (Mrs.) Asima Chatterjee on the occasion of her 86th birthday.
Tetrahedron Letters, 2006
An efficient Zn/AlCl 3 promoted highly regioselective one-pot procedure has been demonstrated for... more An efficient Zn/AlCl 3 promoted highly regioselective one-pot procedure has been demonstrated for the synthesis of β-amino selenides and -sulfides from variety of diselenides/disulfides and aziridines by reductive cleavage of Se-Se and S-S bonds using Zn/AlCl 3 system in acetonitrile under very mild conditions.
Journal of Chemical Research-s, 2003
... using ceric ammonium nitrate: A novel and efficient method for the synthesis of di-and tri-in... more ... using ceric ammonium nitrate: A novel and efficient method for the synthesis of di-and tri-indolylmethanes1, C. Ramesh, N. Ravindranath and Biswanath Das* Organic ... 1961, 26, 4241; (b) A. Chatterjee, S. Manna, J. Banerji, C. Pascard, T. Prange and JN Shoolery; J. Chem. ...
Journal of Molecular Catalysis A-chemical, 2006
A simple and facile synthesis of 14-aryl or alkyl-14-H-dibenzo [a,j]xanthenes has been accomplish... more A simple and facile synthesis of 14-aryl or alkyl-14-H-dibenzo [a,j]xanthenes has been accomplished by treatment of 2-naphthol with aryl or alkyl aldehydes under neat conditions in the presence of molecular iodine as a catalyst. H NMR (200 MHz, CDCl 3 ): δ 8.34 (2H, d, J = 8.0 Hz), 7.88-7.72 (4H, m), 7.60-7.32 (8H, m), 6.93 (2H, d, J = 8.0 Hz), 6.42 (1H, s), 2.42 (2H, q, J = 7.0 Hz), 1.04 (3H, t, J = 7.0 Hz); EIMS: m/z 386 (M • + ) Compound 3d-IR (KBr): 3428, 1632, 1560, 1475, 1229 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.13 (2H, d, J = 8.0 Hz), 7.82-7.68 (4H, m), 7.56-7.30 (8H, m), 6.55 (2H, d, J = 8.0 Hz), 6.38 (1H, s), 4.32 (1H, brs); EIMS: m/z 374 (M • + ). Compound 3f-IR (KBr): 1621, 1592, 1515, 1398, 1244 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.27 (1H, d, J = 8.0 Hz), 7.84-7.75 (4H, m), 7.62-7.33 (9H, m), 7.28-7.15 (2H, m), 6.50 (1H, m); EIMS: m/z 426 (M • + ). Compound 3g-IR (KBr): 1629, 1525, 1475, 1288 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.37 (2H, d, J = 8.0 Hz), 7.82-7.75 (4H, m), 7.59-7.52 (2H, m), 7.48-7.37 (4H, m), 7.12 (1H, dd, J = 8.0, 2.0 Hz), 6.78 (1H, d, J = 2.0 Hz), 6.70 (1H, d, J = 2.0 Hz), 6.38 (1H, s), 5.28 (1H, s), 3.63 (3H, s); EIMS: m/z 404 (M • + ). Compound 3m-IR (CHCl 3 ): 1622, 1591, 1515, 1457, 1240 cm −1 ; 1 H NMR (200 MHz, CDCl 3 ): δ 8.26 (2H, d, J = 8.0 Hz), 7.90-7.72 (4H, m), 7.61-7.49 (2H, m), 7.43-7.32 (4H, m), 5.42 (1H, d, J = 7.0 Hz), 2.28 (1H, m), 0.81 (6H, d, J = 7.0 Hz); EIMS: m/z 324 (M • + ).
Tetrahedron Letters, 2005
a-Bromination of carbonyl compounds (cyclic and acyclic ketones, amides and b-ketoesters) has bee... more a-Bromination of carbonyl compounds (cyclic and acyclic ketones, amides and b-ketoesters) has been achieved efficiently by treatment with N-bromosuccinimide (NBS) and catalyzed by silica-supported sodium hydrogen sulfate (NaHSO 4 AESiO 2 ). The products were formed in high yields under mild reaction conditions and in short reaction times.
Tetrahedron Letters, 2008
A series of anilines were converted into the corresponding N-formyl amines in high yields followi... more A series of anilines were converted into the corresponding N-formyl amines in high yields following the above procedure (Table 1). No additional solvent or catalyst was used. Different functionalities such as alkyl, nitro, halogens and carbonyl remained intact. Anilines containing both ...
Synlett, 2007
... 2a Chetia A, Saikia CJ, Lekhok KC, Boruah RC,Tetrahedron Lett. 2004, 45: 2649. 2b Devi I, Bhu... more ... 2a Chetia A, Saikia CJ, Lekhok KC, Boruah RC,Tetrahedron Lett. 2004, 45: 2649. 2b Devi I, Bhuyan PJ,Tetrahedron Lett. 2004, 45: 8625. ... Catal. A: Chem. 2007, 261: 180. 19a Ramesh C, Ravindranath N, Das B,J. Org. Chem. 2003, 68: 7101. ...
Synlett, 2006
... 2001, 66: 7527. 5b Ramalinga K, Vijayalakshmi P, Kaimal TNB,Tetrahedron Lett. 2002, 43: 879. ... more ... 2001, 66: 7527. 5b Ramalinga K, Vijayalakshmi P, Kaimal TNB,Tetrahedron Lett. 2002, 43: 879. 5c Yadav JS, Reddy BVS, Reddy MS, Prasad AR,Tetrahedron Lett. 2002, 43: 9703. 5d Das B, Banerrjee J, Ramu R, Ravindranath N, Ramesh C,Tetrahedron Lett. 2003, 44: 5465. ...
Tetrahedron Letters, 2007
Benzimidazoles have been efficiently synthesized in high yields by treatment of 1,2-phenylenediam... more Benzimidazoles have been efficiently synthesized in high yields by treatment of 1,2-phenylenediamine with aldehydes using (bromodimethyl)sulfonium bromide at room temperature.
Tetrahedron Letters, 2004
Treatment of aldoximes with activated alkenes in the presence of diacetoxy iodobenzene (DIB) affo... more Treatment of aldoximes with activated alkenes in the presence of diacetoxy iodobenzene (DIB) afforded isoxazolines in high yields. The method has been applied for the preparation of polyfunctional isoxazolines from Baylis-Hillman adducts.
Tetrahedron, 1999
The naturally occurring alkaloids, camptothecin and mappicine ketone were converted to racemic ma... more The naturally occurring alkaloids, camptothecin and mappicine ketone were converted to racemic mappicine acetate which was enantioselectively hydrolyzed to (S)-and (R)-mappicines in high optical purity using baker's yeast and a lipase, Amano PS. Treatment of the racemic acetate with baker's yeast afforded (S)-mappicine while with Amano PS yielded (R)-mappicine. 9-Methoxycamptothecin and 9-methoxymappicine ketone underwent similar conversion to (S)-and (R)-9-methxymappicines.
Journal of Molecular Catalysis A-chemical, 2006
The aza-Michael reactions of amines with ␣,-unsaturated carbonyl and nitrile compounds have effi... more The aza-Michael reactions of amines with ␣,-unsaturated carbonyl and nitrile compounds have efficiently been carried out at room temperature using Amberlyst-15 as a heterogeneous reusable catalyst. The products were formed in short reaction times and in high yields.
Tetrahedron, 2004
The reaction involving the coupling of activated vinylic systems with electrophiles under the cat... more The reaction involving the coupling of activated vinylic systems with electrophiles under the catalytic influence of a tertiary amine (usually DABCO), known as the BaylisHillman reaction, is a useful carbon carbon bond forming method in synthetic organic chemistry. 1 The BaylisHillman ...
Tetrahedron Letters, 2003
Protection of carboxylic acids and subsequent deprotection have been used in multi-step transform... more Protection of carboxylic acids and subsequent deprotection have been used in multi-step transformations and syntheses of several bioactive naturally occurring molecules. [2.] , [3] and [4] Carboxylic acids are frequently protected as esters and unsaturated esters are particularly preferred ...
Pharmaceutical Biology, 2001
This study describes the antibacterial activity of the pure isolates from Piper longum (L.)(black... more This study describes the antibacterial activity of the pure isolates from Piper longum (L.)(black pepper) and Taxus baccata (L.)(Yew). Three isolates of black pepper were active against Gram-positive bacteria and moderately active against Gram-negative bacteria. ...
Organic Letters, 2004
[reaction: see text] Treatment of the acetyl derivatives of the Baylis-Hillman adducts 3-hydroxy-... more [reaction: see text] Treatment of the acetyl derivatives of the Baylis-Hillman adducts 3-hydroxy-2-methylene-alkanoates and 3-hydroxy-2-methylene-alkanenitriles with unactivated alkyl halides in the presence of Zn in saturated aqueous NH(4)Cl solution at room temperature afforded (2E)-2-substituted-alk-2-enoates in the first case and (2Z)-2-substituted-alk-2-enenitriles with high (Z)-selectivity in the second case.
Tetrahedron Letters, 2004
The stereoselective synthesis of (2Z)-2-(chloromethyl)alk-2-enoates has been achieved efficiently... more The stereoselective synthesis of (2Z)-2-(chloromethyl)alk-2-enoates has been achieved efficiently and in high yields and in short reaction times from Baylis-Hillman adducts, 3-hydroxy-2-methylene-alkanoates, by treatment with FeCl 3 or InCl 3 at room temperature.
Tetrahedron Letters, 1998
Two simple and efficient methods for the conversion of the naturally occurring alkaloid, camptoth... more Two simple and efficient methods for the conversion of the naturally occurring alkaloid, camptothecin to mappicine ketone, an antiviral lead compound, have been described. The first method involved the treatment of camptothecin with borontrifluoride etherate and the second method utilised the microwave irradiation of the alkaloid.
Phytochemistry, 2003
Two new pseudoguaianolide-type sesquiterpene lactones, named deacetyltetraneurin A (3) and hyster... more Two new pseudoguaianolide-type sesquiterpene lactones, named deacetyltetraneurin A (3) and hysterone E (4), were isolated from flowers of the plant Parthenium hysterophorus L., along with the seven known compounds parthenin (1), coronopilin, tetraneurin A, 8-b-hydroxycoronopilin, scopoletin, hysterone D, and conchasin A (2). The structures of all the compounds were deduced by means of elemental analysis and extensive spectroscopic (1D and 2D NMR) studies, and confirmed for 3 and 4 by X-ray crystallographic analysis.
Phytochemistry, 2003
Two new flavanoids, 5,7-dimethoxy-3 0 ,4 0 -methylenedioxyflavanone and isobonducellin along with... more Two new flavanoids, 5,7-dimethoxy-3 0 ,4 0 -methylenedioxyflavanone and isobonducellin along with 2 0 -hydroxy-2,3,4 0 ,6 0 -tetramethoxychalcone, 5,7-dimethoxyflavone and bonducellin were isolated from the aerial parts of Caesalpinia pulcherrima. The structures of the compounds were settled mainly by interpretation of their 1D and 2D NMR spectra. Isobonducellin was found to be a homoisoflavanoid containing a cis (Z)-double bond. Antimicrobial activity of the new compounds was evaluated. # Phytochemistry 63 (2003) 789-793 www.elsevier.com/locate/phytochem § Part 41 in the series, ''Studies on Phytochemicals''. Dedicated with regards to Professor (Mrs.) Asima Chatterjee on the occasion of her 86th birthday.