Co-reporter:Tiash Saha;M. Srinivas Lavanya Kumar;Saurav Bera;Bidhu Bhusan Karkara
RSC Advances (2011-Present) 2017 vol. 7(Issue 12) pp:6966-6971
Publication Date(Web):2017/01/20
DOI:10.1039/C6RA25429B
A new synthetic approach has been developed for efficient access to triarylmethanes by palladium catalyzed decarboxylative cross coupling reactions. The reaction features sp2–sp3 coupling where benzoic acids upon decarboxylation reacted with diaryl methyl iodides having both electron donating and withdrawing functionalities, leading to the synthesis of diverse triarylmethanes.
Co-reporter:Priyanka Singh, Sudipta Kumar Manna, Amit Kumar Jana, Tiash Saha, Pankaj Mishra, Saurav Bera, Maloy Kumar Parai, Srinivas Lavanya Kumar M, Sankalan Mondal, Priyanka Trivedi, Vinita Chaturvedi, Shyam Singh, Sudhir Sinha, Gautam Panda
European Journal of Medicinal Chemistry 2015 Volume 95() pp:357-368
Publication Date(Web):5 May 2015
DOI:10.1016/j.ejmech.2015.03.036
•Thiophene containing TRSMs gave most active four antitubercular compounds.•>90% inhibition in multiplication of Mycobacterium tuberculosis within mouse and human macrophages.•S006-830 caused ∼15 fold reduction in viable bacilli in lungs of infected mice.•It was active against single-drug and multi-drug resistant clinical M. tuberculosis isolates.Triarylmethanes (TRAMs) and thiophene containing trisubstituted methanes (TRSMs) have been reported by us, having potential against Mycobacterium tuberculosis and Mycobacterium fortuitum strains, respectively. Further, extension through synthesis and biological evaluation of novel TRSMs resulted into an identified lead 36 (S006-830) [(diisopropyl-(2-{4-[(4-methoxy-phenyl)- thiophen-2-yl-methyl]-phenoxy}-ethyl)-amine)] with MIC: 1.33 mg/L, non-toxic against Vero C-1008 cell line with selectivity index >10, ex vivo efficacy equivalent to first line TB drugs-isoniazid (INH), rifampicin (RFM) and pyrazinamide (PZA) in the mouse and human macrophages, and lung CFU count of 2.2 × 107 (approximately 15 fold lesser than untreated mice, 31 × 107) with efficacies comparable to ethambutol (EMB) (1.27 × 107) and PZA (1.9 × 107). Further, S006-830 also showed potent bactericidal activity against multi-drug resistant and single-drug resistant clinical isolates of M. tuberculosis.Lead S006-830 exhibited MIC: 1.33 mg/L, non-toxic against Vero C-1008 cell with SI > 10, ex vivo efficacy equivalent to first line TB drugs in mouse and human macrophages.
Co-reporter:Saurav Bera, Sanjit Kumar Das, Tiash Saha, Gautam Panda
Tetrahedron Letters 2015 Volume 56(Issue 1) pp:146-149
Publication Date(Web):1 January 2015
DOI:10.1016/j.tetlet.2014.11.045
A highly efficient total synthesis of 3-epi-(+)-lycoricidine has been described for the first time from easily available (S)-Garner aldehyde with an overall yield of 7% in 20 steps. Stereoselective nucleophilic addition, Sharpless asymmetric dihydroxylation, Dess–Martin periodinane oxidation, intramolecular aldol cyclization, and Luche reduction are the salient features of this approach.
Co-reporter:Sudipta Kumar Manna and Gautam Panda
Organic & Biomolecular Chemistry 2014 vol. 12(Issue 41) pp:8318-8324
Publication Date(Web):11 Sep 2014
DOI:10.1039/C4OB00922C
Enantiomerically enriched indolines and tetrahydroisoquinolines were synthesized within 5 min to 2 h in high yields from easily accessible (S)-amino acid derived chiral carbocations. The diastereoselective Friedel–Crafts reaction is promoted by a Lewis acid (AlCl3) offering trans-diastereoselectivity. The rate of the reaction and diastereoselectivity of the product are significantly influenced by steric hindrance of the amino acids substituents and aryl groups. The methodology can be applied for the synthesis of the enantiomerically enriched bioactive scaffold (3S,4R)-demethoxy-3-isopropyl diclofensine.
Co-reporter:Priyanka Singh, Krishnananda Samanta, Sanjit Kumar Das and Gautam Panda
Organic & Biomolecular Chemistry 2014 vol. 12(Issue 33) pp:6297-6339
Publication Date(Web):17 Jun 2014
DOI:10.1039/C4OB00943F
As a result of their easy availability in enantiomerically enriched form and their possession of synthetically transformable diverse functional groups, amino acids have been extensively used by synthetic organic and medicinal chemists as a chiral pool for access to heterocycles (monocycles, bicycles or polycycles, either bridged or fused). This review describes the syntheses of diverse asymmetric heterocycles with various membered rings (n = 3–9) followed by benzo or heteroannulated ones, for the period from 1996 to Dec. 2013. It details solution phase synthetic methodologies in which the naturally occurring α-amino acid is incorporated, totally or partially, into the final product.
Co-reporter:Saurav Bera and Gautam Panda
Organic & Biomolecular Chemistry 2014 vol. 12(Issue 23) pp:3976-3985
Publication Date(Web):08 May 2014
DOI:10.1039/C4OB00639A
An efficient, general and practical synthesis of diverse 3,4-dihydropyrazines, 6,7-dihydro-[1,2,3]triazolopyrazines and 7,8-dihydro-[1,2,3]triazolodiazepines through intramolecular 1,3-dipolar cycloaddition from amino acid derived common intermediates with high yields is described. Moreover, one-pot access to optically active 3-aryl substituted 6,7-dihydro-[1,2,3]triazolo[1,5-a]pyrazines in the palladium–copper co-catalytic system has also been achieved in this work. The easy substrate availability and operational simplicity make the process suitable for further exploration.
Co-reporter:Sudipta Kumar Manna and Gautam Panda
RSC Advances 2014 vol. 4(Issue 40) pp:21032-21041
Publication Date(Web):13 May 2014
DOI:10.1039/C4RA02581D
A microwave assisted efficient route to the synthesis of benzimidazole fused heterocycles through metal catalyzed endo-cyclization strategy involving imine and alkyne activation has been developed. In the presence of [RuCl2(p-cymene)2]2, a variety of 2-ethynyl aldehydes underwent cascade cyclization with substituted benzenediamines to afford the corresponding benzo[4,5]imidazo[2,1-a] pyridine scaffold in moderate to good yields.
Co-reporter:Priyanka Singh and Gautam Panda
RSC Advances 2014 vol. 4(Issue 5) pp:2161-2166
Publication Date(Web):14 Nov 2013
DOI:10.1039/C3RA45409F
The intramolecular aminopalladation reaction of L-serine derived β-hydroxy-γ-alkenylamines undergoes 5-endo-trig cyclization to furnish pyrrolidine rings in high yields. The pyrrolidines thus obtained were used in the synthesis of (−)-8,8a-di-epi-swainsonine, a specific and competitive inhibitor (Ki value 2 × 10−6 M) of lysosomal α-mannosidases.
Co-reporter:Sankalan Mondal and Gautam Panda
RSC Advances 2014 vol. 4(Issue 54) pp:28317-28358
Publication Date(Web):30 Jun 2014
DOI:10.1039/C4RA01341G
The last decade has witnessed a high demand of various synthetic approaches towards bioactive achiral diarylmethanols, diaryl and triarylmethanes and the molecules derived thereof. Their biological and therapeutical relevancy in diverse areas such as antimicrobials, infectious, cardiovascular and nervous system disorders, genital tract diseases, estrogen related disorders and bone remodeling is quite well known. These small molecules have also been the starting materials for the development of a variety of pharmaceutically important compounds. Compounds belonging to this family have not only played a leading role in the development of small molecules as therapeutically useful compounds but also have become one of the mainstays for the development of organic synthesis. However, a comprehensive review which covers their synthesis as well as their biological activity is still lacking. (Two reviews cover the synthesis of chiral diarylmethanols through asymmetric aryl transfer, and three reviews cover the photochemical properties of triarylmethanes, bioconjugation, application of trityl ions and the use of triarylmethanes as dyes.) This review describes the synthesis as well as the biological activities of this group of molecules that came up in the last fifteen years (1995–2013). The current review will cover the various approaches followed for the synthesis of achiral diarylmethanols and the strategies followed for the synthesis of achiral diaryl as well as triarylmethanes. Finally, we will also cover the bioactivities of molecules containing the diaryl and triaryl methane core.
Co-reporter:Priyanka Singh and Gautam Panda
RSC Advances 2014 vol. 4(Issue 60) pp:31892-31903
Publication Date(Web):23 Jul 2014
DOI:10.1039/C4RA04845H
We report easy access to carbohydrate derived diverse tricyclic skeletons which could be beneficial for exploring polyfunctionalized chiral alicycles. The key reaction to assemble a sugar fused tricyclic core is intermolecular tandem esterification and 1,3-dipolar cycloaddition. The framework was elaborated using amide forming reactions, opening of isoxazolidine rings followed by N and O-acylations. The sequences provide distinct, spatially separated and encoded chemical entities that may pave the way to investigate cell functions.
Co-reporter:Sudipta Kumar Manna, Srinivas Lavanya Kumar Manda, Gautam Panda
Tetrahedron Letters 2014 Volume 55(Issue 42) pp:5759-5763
Publication Date(Web):15 October 2014
DOI:10.1016/j.tetlet.2014.08.062
A synthetic approach toward xanthone and fluorenone derivatives through ruthenium catalyzed intra-molecular C–H bond functionalization using an external oxidant has been developed. In the presence of [RuCl2(p-cymene)2]2, a variety of substituted ortho-aryloxy/aryl benzaldehydes underwent cross dehydrogenative coupling to afford the corresponding analogs in moderate to good yields.
Co-reporter:Priyanka Singh, Sudipta Kumar Manna, Gautam Panda
Tetrahedron 2014 70(6) pp: 1363-1374
Publication Date(Web):
DOI:10.1016/j.tet.2013.11.074
Co-reporter:Amit Kumar Jana and Gautam Panda
RSC Advances 2013 vol. 3(Issue 37) pp:16795-16801
Publication Date(Web):16 Jul 2013
DOI:10.1039/C3RA41778F
Two different stereoselective routes for the synthesis of Jaspine B and its C2 epimer are presented here, starting from easily available Garner aldehyde. The key synthetic steps involved iodocyclization, organocuprate addition, HWE olefination, regioselective α-tosylation and cross metathesis reaction. This is the first report to synthesize Jaspine B involving iodocyclization.
Co-reporter:Sanjit Kumar Das and Gautam Panda
RSC Advances 2013 vol. 3(Issue 25) pp:9916-9923
Publication Date(Web):18 Apr 2013
DOI:10.1039/C3RA40648B
An efficient stereoselective synthesis of aminocyclopentitols from (S)- and (R)-Garner aldehydes is presented here. The key steps involved diastereoselective addition of vinylmagnesium bromide to a Garner aldehyde, ring closing metathesis, diastereoselective dihydroxylation and stereoselective reduction of the keto functionality.
Co-reporter:Priyanka Singh, Subal Kumar Dinda, Shagufta and Gautam Panda
RSC Advances 2013 vol. 3(Issue 30) pp:12100-12103
Publication Date(Web):29 May 2013
DOI:10.1039/C3RA41826J
A series of trisubstituted methanes containing aryl and heteroaryl rings, as well as a sulfur spacer between the central methano-carbon and benzene ring, is reported. In an approach towards asymmetric tetrasubstituted methane with high enantioselectivity, chiral tertiary α-hydroxyaldehyde has been synthesized through a Sharpless dihydroxylation on a disubstituted olefin, followed by the chemoselective oxidation of the primary alcohol.
Co-reporter:Ritesh Singh and Gautam Panda
RSC Advances 2013 vol. 3(Issue 42) pp:19533-19544
Publication Date(Web):29 Jul 2013
DOI:10.1039/C3RA42272K
An efficient chiral pool approach using L-proline to access 14-azasteroids under mild reaction conditions has been described. The key step involves the intramolecular SN2′ cyclization reaction for the construction of critical C-ring in the nitrogen impregnated steroidal architectures bearing unsaturation at Δ9(11) position. In the endeavour to synthesize some new congeners, the remote electronic impact of the electron donating groups in A ring and heteroatoms like oxygen in B ring, on the propensity of C-ring cyclization was also observed.
Co-reporter:Sudipta Kumar Manna and Gautam Panda
RSC Advances 2013 vol. 3(Issue 40) pp:18332-18338
Publication Date(Web):29 Jul 2013
DOI:10.1039/C3RA42309C
An efficient synthetic strategy is described for the construction of amino acids derived enantiomerically pure cis-2,5-disubstituted chiral piperazines. Cu-catalyzed spontaneous regioselective ring opening and ring closing of non-activated N-tosyl aziridines as well as Pd-mediated N–C bond formation from N-tosyl halogenated amino-derivatives are the key steps for accessing disubstituted piperazines.
Co-reporter:Ritesh Singh, Gautam Panda
Tetrahedron 2013 69(14) pp: 2853-2884
Publication Date(Web):
DOI:10.1016/j.tet.2013.02.018
Co-reporter:Shailendra Kumar Dhar Dwivedi, Krishnananda Samanta, Manisha Yadav, Amit Kumar Jana, Abhishek Kumar Singh, Bandana Chakravarti, Sankalan Mondal, Rituraj Konwar, Arun Kumar Trivedi, Naibedya Chattopadhyay, Sabyasachi Sanyal, Gautam Panda
Bioorganic & Medicinal Chemistry Letters 2013 23(24) pp: 6816-6821
Publication Date(Web):
DOI:10.1016/j.bmcl.2013.10.013
Co-reporter:Saurav Bera and Gautam Panda
ACS Combinatorial Science 2012 Volume 14(Issue 1) pp:1
Publication Date(Web):November 29, 2011
DOI:10.1021/co200129t
Diastereoselective trans-2,5-disubstituted amino acids derived diverse morpholines, piperazines and thiomorpholines were prepared in 30 min-1 h with high yields through iodine-mediated 6-exotrig type cyclization from a single common synthetic intermediate. The displacement of iodine with hydride ion gave a methyl substituent at the 2-position of morpholines which provides an additional opportunity for diversity oriented nucleophilic substitution on the rings as well as incorporation of substituents at the 5-position from amino acids constituents.Keywords: amino acids; diastereoselective reaction; morpholines; piperazines; thiomorpholines
Co-reporter:Amit Kumar Jana, Sanjit Kumar Das, Gautam Panda
Tetrahedron 2012 68(49) pp: 10114-10121
Publication Date(Web):
DOI:10.1016/j.tet.2012.09.109
Co-reporter:Ritesh Singh and Gautam Panda
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 13) pp:4782-4790
Publication Date(Web):21 Jan 2011
DOI:10.1039/C0OB00892C
An easy, efficient and concise approach to tetrahydrofluorene [6,5,6]ABC tricyclic core embedded new polycycles has been achieved under relatively mild and catalytic Nazarov type electrocyclization conditions, using 2 mol% of Sc(OTf)3 in anhydrous DCM (dichloromethane) at room temperature, with high yields. The generality of the reaction has been illustrated by synthesizing diverse polycycles embedded with rare heterotricyclic [6,5,5]ABC skeletons.
Co-reporter:Krishnananda Samanta and Gautam Panda
Organic & Biomolecular Chemistry 2011 vol. 9(Issue 21) pp:7365-7371
Publication Date(Web):22 Jun 2011
DOI:10.1039/C1OB05462G
A new one-pot synthetic strategy is described for the synthesis of enantiomerically pure cis-3,5-disubstituted morpholines and 3,6-disubstituted 1,4-oxazepanes via tandem aziridine/epoxide ring opening sequences. This new strategy describes how epoxy alcohols could act as both a nucleophile and an electrophile in a tandem fashion and undergo intermolecular regioselective ring opening of chiral aziridines for the first time.
Co-reporter:Saurav Bera, Krishnananda Samanta, Gautam Panda
Tetrahedron Letters 2011 Volume 52(Issue 25) pp:3234-3236
Publication Date(Web):22 June 2011
DOI:10.1016/j.tetlet.2011.04.049
A series of amino acid-derived enantiomerically pure substituted benzo[d][1,2,3,6]oxatriazocine derivatives and 1-alkyl substituted benzotriazoles has been prepared by the diazotization of amino acid-derived benzo-fused alicycles. The first unprecedented diazo-oxygen bond formation in acidic medium led to an entirely new kind of substituted benzo[d][1,2,3,6]oxatriazocine heterocycles.
Co-reporter:Sudipta Kumar Manna, Maloy Kumar Parai, Gautam Panda
Tetrahedron Letters 2011 Volume 52(Issue 45) pp:5951-5955
Publication Date(Web):9 November 2011
DOI:10.1016/j.tetlet.2011.08.127
An efficient synthetic route with good overall yields to access 7-aryl/heteroaryl/alkyl substituted 6H,7H-chromeno[4,3-b]chromene, and 6,7-dihydrothiochromeno[3,2-c]chromene scaffolds has been developed. The route to these xanthene-like analogs involves a three-step reaction sequence: (1) Michael addition of readily available phenol and thiophenol to 4-chloro-2,2-dimethyl-2H-chromene-3-carbaldehyde, (2) Grignard reaction of different aryl, heteroaryl and alkyl magnesium bromides on the resulting carbaldehydes followed by (3) FeCl3 catalyzed spontaneous intramolecular Friedel–Craft’s reaction on the diarylmethyl carbinols.
Co-reporter:Krishnana Samanta ;Dr. Gautam Pa
Chemistry – An Asian Journal 2011 Volume 6( Issue 1) pp:189-197
Publication Date(Web):
DOI:10.1002/asia.201000554
Abstract
An efficient four-step synthetic strategy for cis-2,5-disubstituted chiral piperazines derived from amino-acid-based aziridines is described. The key steps in this strategy are the highly regioselective boron trifluoride diethyl etherate (BF3⋅OEt2)-mediated ring-opening of less-reactive N-Ts chiral aziridines by α-amino acid methyl ester hydrochloride followed by Mitsunobu cyclization. This protocol has been used in an attempt to construct the piperazine core framework of natural product (+)-piperazinomycin.
Co-reporter:Ritesh Singh and Gautam Panda
Organic & Biomolecular Chemistry 2010 vol. 8(Issue 5) pp:1097-1105
Publication Date(Web):06 Jan 2010
DOI:10.1039/B919666H
A general and efficient one-pot cascade/tandem approach to synthesize unsymmetrical 9-aryl/heteroaryl xanthenes has been developed under extremely mild reaction conditions using 10 mol% Sc(OTf)3 as a catalyst. This strategy has been further extended to synthesize 9-(thioaryl) xanthenes through tandem carbon–sulfur (C–S) and carbon–carbon (C–C) bond formation. Novel C–C and C–S bond cleavage promoted by Sc(OTf)3 is also discussed during mechanistic investigation.
Co-reporter:Krishnananda Samanta and Gautam Panda
Organic & Biomolecular Chemistry 2010 vol. 8(Issue 12) pp:2823-2828
Publication Date(Web):22 Apr 2010
DOI:10.1039/C000029A
A new series of enantiomerically pure 2,3,4,4a,5,6-hexahydro-1H-pyrazino[1,2-a]quinoxalines were synthesized for the first time in twelve steps from 1-fluoro-2-nitrobenzene and S-amino acids with 13–20% overall yields. First use of intramolecular Mitsunobu cyclization for 1,2,3,4-tetrahydroquinoxalines followed by PPh3/I2/imidazole mediated 6-exo-tet cyclization were the key steps.
Co-reporter:Sanjit Kumar Das;Sajal Kumar Das ;Gautam Pa
European Journal of Organic Chemistry 2010 Volume 2010( Issue 26) pp:5100-5107
Publication Date(Web):
DOI:10.1002/ejoc.201000619
Abstract
An efficient enantioselective formal total synthesis of antimalarial natural product (–)-raphidecursinol B along with its all stereoisomers is described from commercially available 3,4,5-trimethoxybenzaldehyde using the Sharpless asymmetric dihydroxylation, regioselective α-tosylation, epoxide opening and Mitsunobu reaction as the key reaction steps.
Co-reporter:Jitendra Kumar Mishra, Krishnananda Samanta, Manish Jain, Madhu Dikshit, Gautam Panda
Bioorganic & Medicinal Chemistry Letters 2010 Volume 20(Issue 1) pp:244-247
Publication Date(Web):1 January 2010
DOI:10.1016/j.bmcl.2009.10.126
A diverse group of novel medium ring heterocycles derived from naturally abundant proteinogenic amino acids were evaluated for their potency towards antithrombotic activity. The more potent benzofused oxazepine and oxazocine scaffolds were diversified by incorporating different amino acids at the position number 3. Further the effect of ring size has also been taken into account and it was observed that the eight-membered oxazocines ane more potent compared to the corresponding oxazepines.
Co-reporter:Krishnananda Samanta, Bandana Chakravarti, Jitendra Kumar Mishra, Shailendra Kumar Dhar Dwivedi, Lakshma Vadithe Nayak, Preeti Choudhry, Hemant Kumar Bid, Rituraj Konwar, Naibedya Chattopadhyay, Gautam Panda
Bioorganic & Medicinal Chemistry Letters 2010 Volume 20(Issue 1) pp:283-287
Publication Date(Web):1 January 2010
DOI:10.1016/j.bmcl.2009.10.115
A series of new benzoxazepine derivatives substituted with different alkoxy and aryloxy group were synthesized comprising synthetic steps of Mitsunobu reaction, lithium aluminum hydride (LAH) reduction, followed by debenzylation and finally intramolecular Mitsunobu cyclization. The new benzoxazepines specifically inhibited growth of breast cancer cell lines, MCF-7 and MDA-MB-231, but lack cytotoxicity to normal HEK-293 cells. The cell growth inhibition induced by the active compounds was due to cell cycle arrest at G0/G1 phase. The active compound could cause significant reduction in tumor volume of MCF-7 xenograft tumor in nude mice model and their activity was comparable to that of tamoxifen citrate at 16 mg kg−1 dose at 30 days of treatment. The identified most active compounds of the series have specific advantages as anti-cancer agent in breast cancer than tamoxifen.The active compound based on amino acid based benzoxazepine could cause significant reduction in tumor volume of MCF-7 xenograft tumor in nude mice model and the activity was comparable to that of tamoxifen citrate at 16 mg kg−1 dose at 30 days of treatment.
Co-reporter:Sanjit Kumar Das, Ajay Kumar Srivastava, Gautam Panda
Tetrahedron Letters 2010 Volume 51(Issue 11) pp:1483-1485
Publication Date(Web):17 March 2010
DOI:10.1016/j.tetlet.2010.01.035
A highly efficient and convenient method for the synthesis of substituted chiral 1,4-oxazepanes and 1,4-diazepanes have been described from Garner aldehyde through reductive amination with amino ester hydrochlorides followed by intramolecular cyclization as the key steps.
Co-reporter:Subal Kumar Dinda, Sajal Kumar Das, Gautam Panda
Tetrahedron 2010 66(47) pp: 9304-9309
Publication Date(Web):
DOI:10.1016/j.tet.2010.09.018
Co-reporter:Ritesh Singh, Maloy Kumar Parai and Gautam Panda
Organic & Biomolecular Chemistry 2009 vol. 7(Issue 9) pp:1858-1867
Publication Date(Web):27 Mar 2009
DOI:10.1039/B901632E
A concise and general route to synthesize a new class of [6-5-6] tricyclic core embedded polyheterocycles has been accomplished using diastereoselective Nazarov cyclization with an overall yield of 35–40%. Versatility of this synthetic route has also been demonstrated by accessing a variety of [6-5-5] tricyclic core incorporated polycycles. It was observed that the efficiency of cyclization depends upon the impact of polarization on the reacting systems. Amongst the various Lewis and Brønsted acids screened for cyclization, triflic acid was found to be the most effective catalyst.
Co-reporter:Sajal Kumar Das;Ritesh Singh ;Gautam Pa
European Journal of Organic Chemistry 2009 Volume 2009( Issue 28) pp:4757-4761
Publication Date(Web):
DOI:10.1002/ejoc.200900676
Abstract
A facile and general three-step synthetic route towards unsymmetrical 9-arylxanthenes was developed. The reaction sequence involves nucleophilic substitution of commercially available 2-fluorobenzaldehydes with arenoxides, Grignard reaction of the resulting 2-arenoxybenzaldehydes with arylmagnesium bromides, followed by FeCl3-catalyzed intramolecular diarylmethylation of the resulting carbinols. This strategy was extended to access symmetrical as well as unsymmetrical 9-arylthioxanthenes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Co-reporter:Sajal Kumar Das;Subal Kumar Dinda ;Gautam Pa
European Journal of Organic Chemistry 2009 Volume 2009( Issue 2) pp:204-207
Publication Date(Web):
DOI:10.1002/ejoc.200800661
Abstract
A new asymmetric synthesis of 2,3-disubstituted 1-benzoxepines is described. Key steps include Sharpless asymmetricdihydroxylation of trans-α,β-unsaturated esters and phenoxide ion mediated intramolecular 7-endo-tet carbocyclization of syn-2,3-dihydroxy ester derived cyclic sulfates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Co-reporter:Ajay Kumar Srivastava, Sanjit Kumar Das, Gautam Panda
Tetrahedron 2009 65(27) pp: 5322-5327
Publication Date(Web):
DOI:10.1016/j.tet.2009.04.074
Co-reporter:Maloy Kumar Parai, Gautam Panda
Tetrahedron Letters 2009 50(33) pp: 4703-4705
Publication Date(Web):
DOI:10.1016/j.tetlet.2009.05.104
Co-reporter:Maloy Kumar Parai, Gautam Panda, Vinita Chaturvedi, Y.K. Manju, Sudhir Sinha
Bioorganic & Medicinal Chemistry Letters 2008 Volume 18(Issue 1) pp:289-292
Publication Date(Web):1 January 2008
DOI:10.1016/j.bmcl.2007.10.083
A new series of thiophene containing triarylmethane derivatives were synthesized from the Friedel–Crafts alkylation of diarylcarbinols followed by incorporation of amino alkyl chains. These were evaluated against Mycobacterium tuberculosis H37Rv and showed the activity in the range of 3.12–12.5 μg/mL in vitro.
Co-reporter:Maloy Kumar Parai, Gautam Panda, Kumkum Srivastava, Sunil Kumar Puri
Bioorganic & Medicinal Chemistry Letters 2008 Volume 18(Issue 2) pp:776-781
Publication Date(Web):15 January 2008
DOI:10.1016/j.bmcl.2007.11.038
A new series of benzene and isoquinoline sulfonamide derivatives were synthesized by nucleophilic displacement reaction on benzene and isoquinoline sulfonyl chlorides by substituted amines (primary and secondary). The title compounds were evaluated for antimalarial activity against Plasmodium falciparum in vitro and showed MIC in the range of 2–50 μg/mL.
Co-reporter:Shagufta and Gautam Panda
Organic & Biomolecular Chemistry 2007 vol. 5(Issue 2) pp:360-366
Publication Date(Web):04 Dec 2006
DOI:10.1039/B616155C
A new archetype of steroid–amino acid hybrids containing a nine membered D-ring with hetero atoms has been synthesized for the first time from estrone and amino acids by using Yamaguchi coupling reactions.
Co-reporter:Jitendra Kumar Mishra, Puja Garg, Preeti Dohare, Ashutosh Kumar, Mohammad Imran Siddiqi, Madhur Ray, Gautam Panda
Bioorganic & Medicinal Chemistry Letters 2007 Volume 17(Issue 5) pp:1326-1331
Publication Date(Web):1 March 2007
DOI:10.1016/j.bmcl.2006.12.001
A series of 3-substituted 1, 4-benzodiazepin-2-ones derived from S and R amino acids were evaluated for their anti-ischemic activity in vitro. Treatment with compounds 7h, 16, 9d, and 17 decreased the apoptotic neuronal number, however increased the neuronal viability. The compounds decreasing apoptosis could protect neurons from the ischemic injury. The difference in the activities of 1,4-benzodiazepin-2-ones derived from S- and R-amino acids is discussed and explained on the basis of molecular modeling studies.
Co-reporter:Sajal Kumar Das, Gautam Panda, Vinita Chaturvedi, Y.S. Manju, Anil K. Gaikwad, Sudhir Sinha
Bioorganic & Medicinal Chemistry Letters 2007 Volume 17(Issue 20) pp:5586-5589
Publication Date(Web):15 October 2007
DOI:10.1016/j.bmcl.2007.07.089
A new series of diarylmethylnapthyloxy ethylamines were synthesized by aminoalkylation of diarylmethylnaphthols which were obtained by Friedel–Crafts alkylation on 1- and 2-naphthols using diarylcarbinols as the alkylating agents. The title compounds were evaluated for antitubercular activity against Mycobacterium tuberculosis H37Rv in vitro and showed MIC in the range of 3.12–25 μg/ml.
Co-reporter:Ritesh Singh, Maloy Kumar Parai and Gautam Panda
Organic & Biomolecular Chemistry 2009 - vol. 7(Issue 9) pp:NaN1867-1867
Publication Date(Web):2009/03/27
DOI:10.1039/B901632E
A concise and general route to synthesize a new class of [6-5-6] tricyclic core embedded polyheterocycles has been accomplished using diastereoselective Nazarov cyclization with an overall yield of 35–40%. Versatility of this synthetic route has also been demonstrated by accessing a variety of [6-5-5] tricyclic core incorporated polycycles. It was observed that the efficiency of cyclization depends upon the impact of polarization on the reacting systems. Amongst the various Lewis and Brønsted acids screened for cyclization, triflic acid was found to be the most effective catalyst.
Co-reporter:Priyanka Singh, Krishnananda Samanta, Sanjit Kumar Das and Gautam Panda
Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 33) pp:NaN6339-6339
Publication Date(Web):2014/06/17
DOI:10.1039/C4OB00943F
As a result of their easy availability in enantiomerically enriched form and their possession of synthetically transformable diverse functional groups, amino acids have been extensively used by synthetic organic and medicinal chemists as a chiral pool for access to heterocycles (monocycles, bicycles or polycycles, either bridged or fused). This review describes the syntheses of diverse asymmetric heterocycles with various membered rings (n = 3–9) followed by benzo or heteroannulated ones, for the period from 1996 to Dec. 2013. It details solution phase synthetic methodologies in which the naturally occurring α-amino acid is incorporated, totally or partially, into the final product.
Co-reporter:Krishnananda Samanta and Gautam Panda
Organic & Biomolecular Chemistry 2010 - vol. 8(Issue 12) pp:NaN2828-2828
Publication Date(Web):2010/04/22
DOI:10.1039/C000029A
A new series of enantiomerically pure 2,3,4,4a,5,6-hexahydro-1H-pyrazino[1,2-a]quinoxalines were synthesized for the first time in twelve steps from 1-fluoro-2-nitrobenzene and S-amino acids with 13–20% overall yields. First use of intramolecular Mitsunobu cyclization for 1,2,3,4-tetrahydroquinoxalines followed by PPh3/I2/imidazole mediated 6-exo-tet cyclization were the key steps.
Co-reporter:Ritesh Singh and Gautam Panda
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 13) pp:NaN4790-4790
Publication Date(Web):2011/01/21
DOI:10.1039/C0OB00892C
An easy, efficient and concise approach to tetrahydrofluorene [6,5,6]ABC tricyclic core embedded new polycycles has been achieved under relatively mild and catalytic Nazarov type electrocyclization conditions, using 2 mol% of Sc(OTf)3 in anhydrous DCM (dichloromethane) at room temperature, with high yields. The generality of the reaction has been illustrated by synthesizing diverse polycycles embedded with rare heterotricyclic [6,5,5]ABC skeletons.
Co-reporter:Krishnananda Samanta and Gautam Panda
Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 21) pp:NaN7371-7371
Publication Date(Web):2011/06/22
DOI:10.1039/C1OB05462G
A new one-pot synthetic strategy is described for the synthesis of enantiomerically pure cis-3,5-disubstituted morpholines and 3,6-disubstituted 1,4-oxazepanes via tandem aziridine/epoxide ring opening sequences. This new strategy describes how epoxy alcohols could act as both a nucleophile and an electrophile in a tandem fashion and undergo intermolecular regioselective ring opening of chiral aziridines for the first time.
Co-reporter:Saurav Bera and Gautam Panda
Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 23) pp:NaN3985-3985
Publication Date(Web):2014/05/08
DOI:10.1039/C4OB00639A
An efficient, general and practical synthesis of diverse 3,4-dihydropyrazines, 6,7-dihydro-[1,2,3]triazolopyrazines and 7,8-dihydro-[1,2,3]triazolodiazepines through intramolecular 1,3-dipolar cycloaddition from amino acid derived common intermediates with high yields is described. Moreover, one-pot access to optically active 3-aryl substituted 6,7-dihydro-[1,2,3]triazolo[1,5-a]pyrazines in the palladium–copper co-catalytic system has also been achieved in this work. The easy substrate availability and operational simplicity make the process suitable for further exploration.
Co-reporter:Ritesh Singh and Gautam Panda
Organic & Biomolecular Chemistry 2010 - vol. 8(Issue 5) pp:NaN1105-1105
Publication Date(Web):2010/01/06
DOI:10.1039/B919666H
A general and efficient one-pot cascade/tandem approach to synthesize unsymmetrical 9-aryl/heteroaryl xanthenes has been developed under extremely mild reaction conditions using 10 mol% Sc(OTf)3 as a catalyst. This strategy has been further extended to synthesize 9-(thioaryl) xanthenes through tandem carbon–sulfur (C–S) and carbon–carbon (C–C) bond formation. Novel C–C and C–S bond cleavage promoted by Sc(OTf)3 is also discussed during mechanistic investigation.
Co-reporter:Sudipta Kumar Manna and Gautam Panda
Organic & Biomolecular Chemistry 2014 - vol. 12(Issue 41) pp:NaN8324-8324
Publication Date(Web):2014/09/11
DOI:10.1039/C4OB00922C
Enantiomerically enriched indolines and tetrahydroisoquinolines were synthesized within 5 min to 2 h in high yields from easily accessible (S)-amino acid derived chiral carbocations. The diastereoselective Friedel–Crafts reaction is promoted by a Lewis acid (AlCl3) offering trans-diastereoselectivity. The rate of the reaction and diastereoselectivity of the product are significantly influenced by steric hindrance of the amino acids substituents and aryl groups. The methodology can be applied for the synthesis of the enantiomerically enriched bioactive scaffold (3S,4R)-demethoxy-3-isopropyl diclofensine.
Co-reporter:Shagufta and Gautam Panda
Organic & Biomolecular Chemistry 2007 - vol. 5(Issue 2) pp:NaN366-366
Publication Date(Web):2006/12/04
DOI:10.1039/B616155C
A new archetype of steroid–amino acid hybrids containing a nine membered D-ring with hetero atoms has been synthesized for the first time from estrone and amino acids by using Yamaguchi coupling reactions.
