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Dieter Enders - One of the best experts on this subject based on the ideXlab platform.
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one pot synthesis of 1 substituted 1h Isochromenes by combining bronsted acid with silver catalysis
Synthesis, 2016Co-Authors: Nina Felicitas Brohl, Dipti Sankar Kundu, Gerhard Raabe, Dieter EndersAbstract:A one-pot synthesis of 1-substituted 1 H -Isochromenes employing various 2-alkynyl-benzaldehydes and ketones as substrates under a combination of Bronsted 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.
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asymmetric synthesis of 3 substituted hexahydro 3h Isochromenes via an organocatalytic triple cascade yb catalyzed hetero diels alder sequence
Synthesis, 2012Co-Authors: Nico Erdmann, Iuliana Atodiresei, Dieter EndersAbstract:An efficient two-step asymmetric synthesis of highly substituted 3-alkoxy-hexahydro-3 H -Isochromenes and 3-sulfenylated hexahydro-3 H -Isochromenes is described. The procedure involves an organocatalytic triple cascade reaction, followed by an intermolecular [Yb(fod) 3 ]-catalyzed inverse-electron-demand hetero-Diels–Alder reaction. Using this strategy, a total of six stereogenic centers are obtained with excellent diastereoselectivities and virtually complete enantioselectivities (>95:5 dr, >99% ee).
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Asymmetric Synthesis of 3-Substituted Hexahydro-3H-Isochromenes via an Organocatalytic Triple Cascade/Yb-Catalyzed Hetero-Diels–Alder Sequence
Synthesis, 2012Co-Authors: Nico Erdmann, Iuliana Atodiresei, Dieter EndersAbstract:An efficient two-step asymmetric synthesis of highly substituted 3-alkoxy-hexahydro-3 H -Isochromenes and 3-sulfenylated hexahydro-3 H -Isochromenes is described. The procedure involves an organocatalytic triple cascade reaction, followed by an intermolecular [Yb(fod) 3 ]-catalyzed inverse-electron-demand hetero-Diels–Alder reaction. Using this strategy, a total of six stereogenic centers are obtained with excellent diastereoselectivities and virtually complete enantioselectivities (>95:5 dr, >99% ee).
B Sridhar - One of the best experts on this subject based on the ideXlab platform.
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Tandem Prins and Friedel–Crafts Cyclizations for the Stereoselective Synthesis of trans-Fused Hexahydro-1H-benzo[g]isochromene Derivatives
Synthesis, 2015Co-Authors: B. V. Subba Reddy, Ch. Syama Sundar, M. V. Ramana Reddy, C. Suresh Reddy, B SridharAbstract:Aldehydes and ketones undergo smooth coupling with (4 E )-3-benzyl-5-phenylpent-4-en-1-ol in the presence of scandium(III) triflate (10 mol%) and 4-toluenesulfonic acid (30 mol%) to give the corresponding trans -fused hexahydro-1 H -benzo[ g ]Isochromenes in good yields with excellent selectivity. This is the first example of the synthesis of a trans -fused hexahydro-1 H -benzo[ g ]isochromene derivatives from an aldehyde and (4 E )-3-benzyl-5-phenylpent-4-en-1-ol through tandem Prins and Friedel–Crafts cyclizations.
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the prins cascade cyclization reaction for the synthesis of angularly fused tetrahydropyran and piperidine derivatives
European Journal of Organic Chemistry, 2013Co-Authors: B Subba V Reddy, Harish Kumar, Prashant Borkar, J S Yadav, B SridharAbstract:2-Arylethylbut-3-en-1-ol is found to undergo smooth Prins cascade reactions with various aldehydes in the presence of Sc(OTf)3 (10 mol-%) and a stoichiometric amount of TsOH to afford the corresponding trans-fused hexahydro-1H-benzo[f]Isochromenes in good yields with excellent selectivity. Likewise, N-tosyl-2-phenethylbut-3-en-1-amine gives trans-fused octahydrobenzo[f]isoquinoline derivatives under similar conditions. This is the first example of the synthesis of hexahydro-1H-benzo[f]isochromene and octahydrobenzo-[f]isoquinoline from 2-arylethylbut-3-en-1-ol and N-tosyl-2-phenethylbut-3-en-1-amine, respectively.
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The Prins Cascade Cyclization Reaction for the Synthesis of Angularly‐Fused Tetrahydropyran and Piperidine Derivatives
European Journal of Organic Chemistry, 2013Co-Authors: B. V. Subba Reddy, Harish Kumar, Prashant Borkar, J S Yadav, B SridharAbstract:2-Arylethylbut-3-en-1-ol is found to undergo smooth Prins cascade reactions with various aldehydes in the presence of Sc(OTf)3 (10 mol-%) and a stoichiometric amount of TsOH to afford the corresponding trans-fused hexahydro-1H-benzo[f]Isochromenes in good yields with excellent selectivity. Likewise, N-tosyl-2-phenethylbut-3-en-1-amine gives trans-fused octahydrobenzo[f]isoquinoline derivatives under similar conditions. This is the first example of the synthesis of hexahydro-1H-benzo[f]isochromene and octahydrobenzo-[f]isoquinoline from 2-arylethylbut-3-en-1-ol and N-tosyl-2-phenethylbut-3-en-1-amine, respectively.
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Tandem Prins/Friedel-Crafts cyclization for stereoselective synthesis of heterotricyclic systems.
Journal of Organic Chemistry, 2011Co-Authors: Basi Subba Reddy, B Sridhar, Prashant Borkar, Jhillu Yadav, René GréeAbstract:Homoallylic substrates such as (E)-6-arylhex-3-enyl alcohols, N-tosylamides, and thiols undergo smooth cross-coupling with various aldehydes in the presence of 10 mol % Sc(OTf)3 and 30 mol % TsOH to afford the trans-fused hexahydro-1H-benzo[f]Isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes, respectively. However, the cross-coupling of (Z)-olefins such as 6-arylhex-3-enyl alcohols, N-tosylamides, and thiols with aldehydes affords the corresponding hexahydro-1H-benzo[f]Isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes with complete cis selectivity via intramolecular Prins-, aza-Prins-, and thia-Prins/Friedel-Crafts cyclizations, respectively. Though the Prins cyclization proceeds smoothly under the influence of Sc(OTf)3, high conversions and enhanced reaction rates are achieved using a mixture of Sc(OTf)3 and TsOH (1:3).
Nico Erdmann - One of the best experts on this subject based on the ideXlab platform.
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asymmetric synthesis of 3 substituted hexahydro 3h Isochromenes via an organocatalytic triple cascade yb catalyzed hetero diels alder sequence
Synthesis, 2012Co-Authors: Nico Erdmann, Iuliana Atodiresei, Dieter EndersAbstract:An efficient two-step asymmetric synthesis of highly substituted 3-alkoxy-hexahydro-3 H -Isochromenes and 3-sulfenylated hexahydro-3 H -Isochromenes is described. The procedure involves an organocatalytic triple cascade reaction, followed by an intermolecular [Yb(fod) 3 ]-catalyzed inverse-electron-demand hetero-Diels–Alder reaction. Using this strategy, a total of six stereogenic centers are obtained with excellent diastereoselectivities and virtually complete enantioselectivities (>95:5 dr, >99% ee).
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Asymmetric Synthesis of 3-Substituted Hexahydro-3H-Isochromenes via an Organocatalytic Triple Cascade/Yb-Catalyzed Hetero-Diels–Alder Sequence
Synthesis, 2012Co-Authors: Nico Erdmann, Iuliana Atodiresei, Dieter EndersAbstract:An efficient two-step asymmetric synthesis of highly substituted 3-alkoxy-hexahydro-3 H -Isochromenes and 3-sulfenylated hexahydro-3 H -Isochromenes is described. The procedure involves an organocatalytic triple cascade reaction, followed by an intermolecular [Yb(fod) 3 ]-catalyzed inverse-electron-demand hetero-Diels–Alder reaction. Using this strategy, a total of six stereogenic centers are obtained with excellent diastereoselectivities and virtually complete enantioselectivities (>95:5 dr, >99% ee).
Bo Jiang - One of the best experts on this subject based on the ideXlab platform.
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Tunable Dimerization and Trimerization of β‐Alkynyl Ketones via Silver Catalysis for Accessing Spiro and Dispiro Compounds Containing 1H‐Isochromene
Advanced Synthesis & Catalysis, 2017Co-Authors: Dan Wang, Armando Paniagua, Shujiang Tu, Guigen Li, Bo JiangAbstract:New silver-catalyzed tunable dimerization and trimerization of β-alkynyl ketones have been established, enabling multiple C-C bond-forming events to selectively access skeletally diverse spiro Isochromenes with generally good yields. The silver-enabled bicycloaddition of β-alkynyl ketones with water offered hydroxylated spiro Isochromenes. Without water, spiro Isochromenes with methylene moiety were obtained through catalytic 6-endo-dig oxo-cyclization/[4+2] cycloaddition cascades by using pyridine as additives whereas employment of 1,1‘-binaphthyl-2,2‘-diyl hydrogen phosphate (BiNPO4H) as a Bronsted acid catalyst rendered the unprecedented dispiro trimerization products through double C(sp3)-H functionalization.
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silver mediated radical c sp3 h biphosphinylation and nitration of β alkynyl ketones for accessing functional Isochromenes
Organic Letters, 2017Co-Authors: Yanan Wu, Shujiang Tu, Guigen Li, Bo JiangAbstract:Silver-mediated C(sp3)–H functionalization and 6-endo-dig oxo-cyclization of conjugated β-alkynyl ketones have been established under oxidative conditions. The reaction leads to the concise formation of a wide range of Isochromenes via C(sp3)–H bond-breaking and radical addition steps. Dual and monofunctional isochromene products were selectively controlled by using either electron-rich or electron-deficient radical sources.
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Silver-Mediated Radical C(sp3)–H Biphosphinylation and Nitration of β‑Alkynyl Ketones for Accessing Functional Isochromenes
2017Co-Authors: Jun Sun, Jiang-kai Qiu, Wen-juan Hao, Cheng Guo, Bo JiangAbstract:Silver-mediated C(sp3)–H functionalization and 6-endo-dig oxo-cyclization of conjugated β-alkynyl ketones have been established under oxidative conditions. The reaction leads to the concise formation of a wide range of Isochromenes via C(sp3)–H bond-breaking and radical addition steps. Dual and monofunctional isochromene products were selectively controlled by using either electron-rich or electron-deficient radical sources
Bijoy Kundu - One of the best experts on this subject based on the ideXlab platform.
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synthesis of triazolo isoquinolines and Isochromenes from 2 alkynylbenzaldehyde via domino reactions under transition metal free conditions
Journal of Organic Chemistry, 2013Co-Authors: Ravi Kiran Arigela, Srinivas Samala, Rohit Mahar, Sanjeev K Shukla, Bijoy KunduAbstract:We describe two simple straightforward syntheses of triazolo isoquinolines (3) and Isochromenes (7) from 2-alkynylbenzaldehydes (1) as a common synthon. The synthetic strategy for 3 involves formation of the (E)-1-(2-nitrovinyl)-2-(alkynyl)benzene species 2 via condensation of synthon 1 with nitromethane followed by a [3 + 2] cycloaddition/extrusion of the nitro group/regioselective 6-endo cyclization domino sequence. In yet another strategy, the synthon 1 was condensed with nitromethane followed by electrophilic iodo cyclization of the resulting 2-nitro-1-(2-(alkynyl)phenyl)ethanol (6) to furnish iodo isochromene derivatives. The salient feature of the above two strategies involves formation of the corresponding heterocycles under metal-free conditions in good yields.
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Synthesis of Triazolo Isoquinolines and Isochromenes from 2‑Alkynylbenzaldehyde via Domino Reactions under Transition-Metal-Free Conditions
2013Co-Authors: Ravi Kiran Arigela, Srinivas Samala, Rohit Mahar, Sanjeev K Shukla, Bijoy KunduAbstract:We describe two simple straightforward syntheses of triazolo isoquinolines (3) and Isochromenes (7) from 2-alkynylbenzaldehydes (1) as a common synthon. The synthetic strategy for 3 involves formation of the (E)-1-(2-nitrovinyl)-2-(alkynyl)benzene species 2 via condensation of synthon 1 with nitromethane followed by a [3 + 2] cycloaddition/extrusion of the nitro group/regioselective 6-endo cyclization domino sequence. In yet another strategy, the synthon 1 was condensed with nitromethane followed by electrophilic iodo cyclization of the resulting 2-nitro-1-(2-(alkynyl)phenyl)ethanol (6) to furnish iodo isochromene derivatives. The salient feature of the above two strategies involves formation of the corresponding heterocycles under metal-free conditions in good yields
