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Papers by dipti sankar kundu
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Synthesis, 2017
A highly diastereo- and enantioselective Mannich reaction of N-acetylindolin-3-ones with isatin N... more A highly diastereo- and enantioselective Mannich reaction of N-acetylindolin-3-ones with isatin N-Boc ketimines to form 2,3′-connected bis-indolinones is developed employing a low loading of a readily available bifunctional thiourea catalyst. The asymmetric synthesis connects two indolinones via a vic-diamine unit and generates two neighboring stereocenters.
Synthesis, 2016
A one-pot synthesis of 1-substituted 1H-isochromenes employing various 2-alkynyl-benzaldehydes an... more A one-pot synthesis of 1-substituted 1H-isochromenes employing various 2-alkynyl-benzaldehydes and ketones as substrates under a combination of Brønsted acid and silver catalysis has been developed. The isochromenes, which are present as important heterocyclic core structures in many bioactive and natural compounds, are obtained in medium to excellent yields with diastereomeric ratios of up to 9:1. A first enantioselective variant has also been tested. Key words isochromene, Brønsted acid catalysis, silver catalysis, organocatalysis, one-pot synthesis 12 c Ag 2 CO 3 DPP 40 16 n-hexane 86 13 Ag 2 O DPP 40 16 n-hexane 37 14 AgOTf DPP 40 16 n-hexane 29 15 AgBF 4 DPP 40 16 n-hexane nr 16 AgNO 3 DPP 40 16 n-hexane nr 17 d Ag 2 CO 3 DPP 40 16 n-hexane 93 a Reaction conditions: 1a (0.4 mmol), 2a (0.4 mmol), acid (10 mol%), Ag 2 CO 3 (0.008 mmol), n-hexane (0.3 M, 2.4 mL), 40 °C, 17 h. b Yield of isolated 3a after flash chromatography. c Acetyl acetone (2 equiv) used. d Compound 2a (0.8 mmol), Ag 2 CO 3 (2.5 mol%) used and the concentration reduced to 0.17 M in n-hexane.
Journal of the American Chemical Society, 2017
A Brønsted acid catalyzed kinetic resolution of primary amines is described that is based on the ... more A Brønsted acid catalyzed kinetic resolution of primary amines is described that is based on the condensation between an amine and a carbonyl compound. 1,3-Diketones react with racemic α-branched amines to furnish the corresponding enantioenriched enaminone and recovered starting material. Good to excellent enantioselectivity was observed with both aromatic and aliphatic primary amines. This process represents the first small-molecule catalyzed kinetic resolution of aliphatic amines.
Synlett, 2009
The amidation of aryl iodides using Cu 2 O nanoparticles is described. It is a heterogeneous proc... more The amidation of aryl iodides using Cu 2 O nanoparticles is described. It is a heterogeneous process, no leaching of the Cu 2 O species occurs, and the catalyst can be recovered and recycled without loss of activity.
Journal of Fluorine Chemistry, 2010
Titanium tetrafluoride can efficiently be used for strereoselective synthesis of 4-fluorotetrahyd... more Titanium tetrafluoride can efficiently be used for strereoselective synthesis of 4-fluorotetrahydropyrans via Prins cyclization in good yields. The method is general and can be used for aldehydes as well as ketones.
Chemical Communications, 2014
Microporous polymer networks based on binaphthyl phosphoric acids are suitable heterogeneous asym... more Microporous polymer networks based on binaphthyl phosphoric acids are suitable heterogeneous asymmetric organocatalysts. Herein we show that the porous characteristics of such networks can be fine-tuned by co-polymerisation. This enables us to investigate the influence of the surface area and porosity in microporous networks on their catalytic performance. In this case, the activity of the polymers in an asymmetric hydrogenation reaction is increased by the use of polymers with higher surface areas. Scheme 1 Monomers used for the co-polymerisation: BNPPA (1) and TTB (2).
Angewandte Chemie International Edition, 2012
Dedicated to Professor Ekkehard Winterfeldt on the occasion of his 80th birthday [**] This work w... more Dedicated to Professor Ekkehard Winterfeldt on the occasion of his 80th birthday [**] This work was supported by the Cluster of Excellence "Unifying Concepts in Catalysis" and the "Berlin International Graduate School of Natural Sciences and Engineering". Binol = 1,1'-binaphthalene-2,2'-diol.
Advanced Synthesis & Catalysis, 2011
... A Chiral Microporous Polymer Network as Asymmetric Heterogeneous Organocatalyst. Christian Bl... more ... A Chiral Microporous Polymer Network as Asymmetric Heterogeneous Organocatalyst. Christian Bleschke 1 ,; Johannes Schmidt 2,* ,; Dipti S. Kundu 1 ,; Siegfried Blechert 1,* ,; Arne Thomas 2. Article first published online: 16 NOV 2011. ... X. Jiang, A. Cooper, Top. Curr. Chem. Vol ...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Synthesis, 2017
A highly diastereo- and enantioselective Mannich reaction of N-acetylindolin-3-ones with isatin N... more A highly diastereo- and enantioselective Mannich reaction of N-acetylindolin-3-ones with isatin N-Boc ketimines to form 2,3′-connected bis-indolinones is developed employing a low loading of a readily available bifunctional thiourea catalyst. The asymmetric synthesis connects two indolinones via a vic-diamine unit and generates two neighboring stereocenters.
Synthesis, 2016
A one-pot synthesis of 1-substituted 1H-isochromenes employing various 2-alkynyl-benzaldehydes an... more A one-pot synthesis of 1-substituted 1H-isochromenes employing various 2-alkynyl-benzaldehydes and ketones as substrates under a combination of Brønsted acid and silver catalysis has been developed. The isochromenes, which are present as important heterocyclic core structures in many bioactive and natural compounds, are obtained in medium to excellent yields with diastereomeric ratios of up to 9:1. A first enantioselective variant has also been tested. Key words isochromene, Brønsted acid catalysis, silver catalysis, organocatalysis, one-pot synthesis 12 c Ag 2 CO 3 DPP 40 16 n-hexane 86 13 Ag 2 O DPP 40 16 n-hexane 37 14 AgOTf DPP 40 16 n-hexane 29 15 AgBF 4 DPP 40 16 n-hexane nr 16 AgNO 3 DPP 40 16 n-hexane nr 17 d Ag 2 CO 3 DPP 40 16 n-hexane 93 a Reaction conditions: 1a (0.4 mmol), 2a (0.4 mmol), acid (10 mol%), Ag 2 CO 3 (0.008 mmol), n-hexane (0.3 M, 2.4 mL), 40 °C, 17 h. b Yield of isolated 3a after flash chromatography. c Acetyl acetone (2 equiv) used. d Compound 2a (0.8 mmol), Ag 2 CO 3 (2.5 mol%) used and the concentration reduced to 0.17 M in n-hexane.
Journal of the American Chemical Society, 2017
A Brønsted acid catalyzed kinetic resolution of primary amines is described that is based on the ... more A Brønsted acid catalyzed kinetic resolution of primary amines is described that is based on the condensation between an amine and a carbonyl compound. 1,3-Diketones react with racemic α-branched amines to furnish the corresponding enantioenriched enaminone and recovered starting material. Good to excellent enantioselectivity was observed with both aromatic and aliphatic primary amines. This process represents the first small-molecule catalyzed kinetic resolution of aliphatic amines.
Synlett, 2009
The amidation of aryl iodides using Cu 2 O nanoparticles is described. It is a heterogeneous proc... more The amidation of aryl iodides using Cu 2 O nanoparticles is described. It is a heterogeneous process, no leaching of the Cu 2 O species occurs, and the catalyst can be recovered and recycled without loss of activity.
Journal of Fluorine Chemistry, 2010
Titanium tetrafluoride can efficiently be used for strereoselective synthesis of 4-fluorotetrahyd... more Titanium tetrafluoride can efficiently be used for strereoselective synthesis of 4-fluorotetrahydropyrans via Prins cyclization in good yields. The method is general and can be used for aldehydes as well as ketones.
Chemical Communications, 2014
Microporous polymer networks based on binaphthyl phosphoric acids are suitable heterogeneous asym... more Microporous polymer networks based on binaphthyl phosphoric acids are suitable heterogeneous asymmetric organocatalysts. Herein we show that the porous characteristics of such networks can be fine-tuned by co-polymerisation. This enables us to investigate the influence of the surface area and porosity in microporous networks on their catalytic performance. In this case, the activity of the polymers in an asymmetric hydrogenation reaction is increased by the use of polymers with higher surface areas. Scheme 1 Monomers used for the co-polymerisation: BNPPA (1) and TTB (2).
Angewandte Chemie International Edition, 2012
Dedicated to Professor Ekkehard Winterfeldt on the occasion of his 80th birthday [**] This work w... more Dedicated to Professor Ekkehard Winterfeldt on the occasion of his 80th birthday [**] This work was supported by the Cluster of Excellence "Unifying Concepts in Catalysis" and the "Berlin International Graduate School of Natural Sciences and Engineering". Binol = 1,1'-binaphthalene-2,2'-diol.
Advanced Synthesis & Catalysis, 2011
... A Chiral Microporous Polymer Network as Asymmetric Heterogeneous Organocatalyst. Christian Bl... more ... A Chiral Microporous Polymer Network as Asymmetric Heterogeneous Organocatalyst. Christian Bleschke 1 ,; Johannes Schmidt 2,* ,; Dipti S. Kundu 1 ,; Siegfried Blechert 1,* ,; Arne Thomas 2. Article first published online: 16 NOV 2011. ... X. Jiang, A. Cooper, Top. Curr. Chem. Vol ...