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Indrapal Singh Aidhen - One of the best experts on this subject based on the ideXlab platform.
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a Weinreb Amide based building block for convenient access to β β diarylacroleins synthesis of 3 arylindanones
European Journal of Organic Chemistry, 2016Co-Authors: Praveen Kumar Tiwari, Indrapal Singh AidhenAbstract:Towards the synthesis of symmetrical and unsymmetrical β,β-diarylacroleins for assembling diarylmethine fragments present in biologically important molecules, we have developed a new Weinreb Amide (WA) based building block, derived from propiolic acid. The WA functionality present in this compound allowed the sequential addition of various arylmagnesium bromide reagents in a controlled manner. The developed methodology for the access to β,β-diarylacroleins has been utilised for the synthesis of biologically important 3-arylindanone molecules.
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A Weinreb Amide Based Building Block for Convenient Access to β,β‐Diarylacroleins: Synthesis of 3‐Arylindanones
European Journal of Organic Chemistry, 2016Co-Authors: Praveen Kumar Tiwari, Indrapal Singh AidhenAbstract:Towards the synthesis of symmetrical and unsymmetrical β,β-diarylacroleins for assembling diarylmethine fragments present in biologically important molecules, we have developed a new Weinreb Amide (WA) based building block, derived from propiolic acid. The WA functionality present in this compound allowed the sequential addition of various arylmagnesium bromide reagents in a controlled manner. The developed methodology for the access to β,β-diarylacroleins has been utilised for the synthesis of biologically important 3-arylindanone molecules.
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Study of the Chemoselectivity of Grignard Reagent Addition to Substrates Containing Both Nitrile and Weinreb Amide Functionalities
European Journal of Organic Chemistry, 2013Co-Authors: Kommidi Harikrishna, Ananya Rakshit, Indrapal Singh AidhenAbstract:Several substrates containing both cyano and Weinreb Amide functionalities have been synthesized to study the chemoselectivity of their reactions with organomagnesium bromides (ArMgBr and RMgBr). Excellent chemoselectivity towards the Weinreb Amide was observed in most cases, even in the presence of excess Grignard reagent, affording cyano ketones in good-to-excellent yields.
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convenient access to acyl substituted bis styrylbenzenes based on building blocks using julia olefination and Weinreb Amide chemistry
European Journal of Organic Chemistry, 2013Co-Authors: Ramesh Mukkamala, A. Senthilmurugan, Indrapal Singh AidhenAbstract:In an effort to arrive at bis(styrylbenzene) derivatives, which are known for their importance in connection to Alzheimer's disease, two bifunctional building blocks that enable a C–C bond formation through a Julia–Kocienski reaction were synthesized. The orthogonal nature of the two functional groups in these building blocks allow the sequential olefination of commercially available aromatic aldehydes and the intermediate stilbene aldehydes to deliver an efficient and new route for bis(styrylbenzenes) with Weinreb Amide (WA) functionality for the first time. The successful incorporation of the WA functionality has facilitated convenient access to unknown bis(styrylbenzenes) with acyl and formyl groups as substituents This strategy has also paved the way for highly functionalized bis(styrylbenzenes) with a tetrafluorophenyl core, which have potential as new contrast agents for MRI applications.
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Convenient Access to Acyl‐Substituted Bis(styrylbenzenes) Based on Building Blocks Using Julia Olefination and Weinreb Amide Chemistry
European Journal of Organic Chemistry, 2013Co-Authors: Ramesh Mukkamala, A. Senthilmurugan, Indrapal Singh AidhenAbstract:In an effort to arrive at bis(styrylbenzene) derivatives, which are known for their importance in connection to Alzheimer's disease, two bifunctional building blocks that enable a C–C bond formation through a Julia–Kocienski reaction were synthesized. The orthogonal nature of the two functional groups in these building blocks allow the sequential olefination of commercially available aromatic aldehydes and the intermediate stilbene aldehydes to deliver an efficient and new route for bis(styrylbenzenes) with Weinreb Amide (WA) functionality for the first time. The successful incorporation of the WA functionality has facilitated convenient access to unknown bis(styrylbenzenes) with acyl and formyl groups as substituents This strategy has also paved the way for highly functionalized bis(styrylbenzenes) with a tetrafluorophenyl core, which have potential as new contrast agents for MRI applications.
Kavirayani R. Prasad - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of the C9-C22 fragment of polyene polyol containing macrolactone natural product pentamycin
Tetrahedron, 2020Co-Authors: Amit K. Bali, Kavirayani R. PrasadAbstract:Abstract Stereoselective synthesis of the C9-C22 fragment of pentamycin from the bis-Weinreb Amide of d -tartaric acid was accomplished in 12 steps (14% yield). Key reactions in the synthesis include Ley’s dithiaketalization, Narasaka stereoselective reduction of the β-hydroxy ketone and Wittig reaction with a vinylogous phosphonate.
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Efficient enantiospecific synthesis of ent-conduramine F-1
Tetrahedron, 2018Co-Authors: Kavirayani R. Prasad, Vipin Ashok RangariAbstract:Abstract An efficient enantiospecific total synthesis of ent-conduramine F-1 (aminocyclohexenetriol) was accomplished starting from the bis-Weinreb Amide of tartaric acid. Key reactions in the synthesis include the desymmetrization of tartaric acid Amide with vinylmagnesium bromide and installation of the required amine using Ellman sulfinimine. Ring closing metathesis was used to synthesize the required alkene in the cyclohexene.
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Enantiospecific total synthesis of macrolactone Sch 725674.
Organic Letters, 2014Co-Authors: Amit K. Bali, Sunil Kumar Sunnam, Kavirayani R. PrasadAbstract:The enantiospecific total synthesis of 14-membered macrolactone Sch 725674 was accomplished from tartaric acid. Key reactions in the synthesis include the Ley's dithiaketalization of an alkynone derived from the bis-Weinreb Amide of tartaric acid, Boord olefination, and ring-closing metathesis of an acrylate ester.
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Enantiospecific Total Synthesis of Macrolactone Sch 725674
2014Co-Authors: Amit K. Bali, Sunil Kumar Sunnam, Kavirayani R. PrasadAbstract:The enantiospecific total synthesis of 14-membered macrolactone Sch 725674 was accomplished from tartaric acid. Key reactions in the synthesis include the Ley’s dithiaketalization of an alkynone derived from the bis-Weinreb Amide of tartaric acid, Boord olefination, and ring-closing metathesis of an acrylate ester
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Stereoselective synthesis of (+)-boronolide and (−)-5-epi-boronolide
Tetrahedron: Asymmetry, 2006Co-Authors: Kavirayani R. Prasad, Pazhamalai AnbarasanAbstract:Abstract Stereoselective synthesis of boronolide and 5-epi-boronolide was achieved from d -(−)-tartaric acid. The key step involves the reduction of a keto Weinreb Amide for the synthesis of boronolide, and a single pot construction of a diketone from the bis-Weinreb Amide of tartaric acid and subsequent reduction with L-Selectride for 5-epi-boronolide.
Jean Martinez - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of chiral α-amino aldehydes linked by their amine function to solid support
Journal of peptide science : an official publication of the European Peptide Society, 2004Co-Authors: Sonia Cantel, Annie Heitz, Jean Martinez, Jean-alain FehrentzAbstract:The anchoring of an α-amino-acid derivative by its amine function on to a solid support allows some chemical reactions starting from the carboxylic acid function. This paper describes the preparation of α-amino aldehydes linked to the support by their amine function. This was performed by reduction with LiAlH4 of the corresponding Weinreb Amide linked to the resin. The aldehydes obtained were then involved in Wittig or reductive amination reactions. In addition, the linked Weinreb Amide was reacted with methylmagnesium bromide to yield the corresponding ketone. After cleavage from the support, the compounds were obtained in good to excellent yields and characterized. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
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Synthesis of peptide aldehydes on solid support
Reactive & Functional Polymers, 1999Co-Authors: Marielle Paris, Annie Heitz, Jean Martinez, Catherine Pothion, Laurent Goulleux, Jean-alain FehrentzAbstract:Peptide aldehydes are of great interest as enzyme inhibitors and as starting materials for further chemistry. The solid phase synthesis of such entities is presented through three different approaches: a Weinreb Amide linker, a phenyl ester linker, which both can be reduced with hydrides to yield the target molecules, and finally an unsaturated linker which produces the desired compounds by ozonolysis.
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Solid Phase Synthesis of C-Terminal Peptide Aldehydes
The Journal of Organic Chemistry, 1997Co-Authors: Jean-alain Fehrentz, Annie Heitz, Marielle Paris, Jiri Velek, Francois Winternitz, Jean MartinezAbstract:Peptides with C-terminal aldehydes (PAs) are of interest due to their inhibitory properties toward numerous classes of proteolytic enzymes. In this paper, we describe and compare two novel approaches for the preparation of PAs by solid phase synthesis, one based on the reduction of the Weinreb Amide and the other on the reduction of phenyl esters. A study showed that purification of the PAs by chromatography (silica gel or reversed phase) induced a loss of the optical integrity of the C-terminal residue. Both methods were found to be suitable for the synthesis of PAs which were then used for the preparation of reduced-bond-containing peptides on insoluble polymers. The Weinreb Amide approach was preferred for the synthesis of PAs due to an uncontrolled over-reduction of phenyl esters in our hands.
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Improved solid phase synthesis of C-terminal peptide aldehydes
Tetrahedron Letters, 1995Co-Authors: Jean-alain Fehrentz, Chuan-fa Liu, Annie Heitz, Marielle Paris, Jiri Velek, Francois Winternitz, Jean MartinezAbstract:Abstract A new linker based on the Weinreb Amide was developed in order to synthesize from peptidyl-resin the corresponding aldehydic peptides by reduction with LiAlH This new reaction was tested with N-protected amino-residues and with tripeptides to obtain the corresponding aldehydes without racemisation.
Jean-alain Fehrentz - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of chiral α-amino aldehydes linked by their amine function to solid support
Journal of peptide science : an official publication of the European Peptide Society, 2004Co-Authors: Sonia Cantel, Annie Heitz, Jean Martinez, Jean-alain FehrentzAbstract:The anchoring of an α-amino-acid derivative by its amine function on to a solid support allows some chemical reactions starting from the carboxylic acid function. This paper describes the preparation of α-amino aldehydes linked to the support by their amine function. This was performed by reduction with LiAlH4 of the corresponding Weinreb Amide linked to the resin. The aldehydes obtained were then involved in Wittig or reductive amination reactions. In addition, the linked Weinreb Amide was reacted with methylmagnesium bromide to yield the corresponding ketone. After cleavage from the support, the compounds were obtained in good to excellent yields and characterized. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
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Synthesis of peptide aldehydes on solid support
Reactive & Functional Polymers, 1999Co-Authors: Marielle Paris, Annie Heitz, Jean Martinez, Catherine Pothion, Laurent Goulleux, Jean-alain FehrentzAbstract:Peptide aldehydes are of great interest as enzyme inhibitors and as starting materials for further chemistry. The solid phase synthesis of such entities is presented through three different approaches: a Weinreb Amide linker, a phenyl ester linker, which both can be reduced with hydrides to yield the target molecules, and finally an unsaturated linker which produces the desired compounds by ozonolysis.
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Solid Phase Synthesis of C-Terminal Peptide Aldehydes
The Journal of Organic Chemistry, 1997Co-Authors: Jean-alain Fehrentz, Annie Heitz, Marielle Paris, Jiri Velek, Francois Winternitz, Jean MartinezAbstract:Peptides with C-terminal aldehydes (PAs) are of interest due to their inhibitory properties toward numerous classes of proteolytic enzymes. In this paper, we describe and compare two novel approaches for the preparation of PAs by solid phase synthesis, one based on the reduction of the Weinreb Amide and the other on the reduction of phenyl esters. A study showed that purification of the PAs by chromatography (silica gel or reversed phase) induced a loss of the optical integrity of the C-terminal residue. Both methods were found to be suitable for the synthesis of PAs which were then used for the preparation of reduced-bond-containing peptides on insoluble polymers. The Weinreb Amide approach was preferred for the synthesis of PAs due to an uncontrolled over-reduction of phenyl esters in our hands.
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Improved solid phase synthesis of C-terminal peptide aldehydes
Tetrahedron Letters, 1995Co-Authors: Jean-alain Fehrentz, Chuan-fa Liu, Annie Heitz, Marielle Paris, Jiri Velek, Francois Winternitz, Jean MartinezAbstract:Abstract A new linker based on the Weinreb Amide was developed in order to synthesize from peptidyl-resin the corresponding aldehydic peptides by reduction with LiAlH This new reaction was tested with N-protected amino-residues and with tripeptides to obtain the corresponding aldehydes without racemisation.
Yasuko Okamoto - One of the best experts on this subject based on the ideXlab platform.
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convergent synthesis of 4 6 unsubstituted 5 acyl 2 aminodihydropyrimidines using Weinreb Amide
Tetrahedron Letters, 2017Co-Authors: Yoshio Nishimura, Takanori Kubo, Yasuko OkamotoAbstract:Abstract A method of convergent synthesis of novel 4,6-unsubstituted 5-acyl-2-aminodihydropyrimidines 7 is developed. The synthetic intermediate of 7 , 4,6-unsubstituted 2-aminodihydropyrimidines 9 having a Weinreb Amide at the 5-position, is prepared by the sequential Staudinger/aza-Wittig/cyclization reactions of ( E )- tert -butyl{3-azido-2-[methoxy(methyl)carbamoyl]allyl}carbamate ( E )- 10 . The transformation of the Weinreb Amide of 9 to an acyl group proceeds smoothly by a substitution reaction using aryllithiums or alkyllithiums in the presence of a catalytic amount of BF 3 etherate, affording 7 in good to high yield. The N -protecting group of 7 can be easily removed to obtain N -unsubstituted 2-amino-5-acyldihydropyrimidines 8 , and the derivatives are observed as a single isomer in 1 H NMR spectroscopy. All dihydropyrimidines in this study were hitherto unavailable and difficult to synthesize by conventional methods.
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convergent synthesis of 4 6 unsubstituted 5 acyl 2 phenyldihydropyrimidines by substitution reactions of Weinreb Amide group of tetrahydropyrimidines
Tetrahedron Letters, 2016Co-Authors: Yoshio Nishimura, Takanori Kubo, Yasuko OkamotoAbstract:A method of convergent and stepwise synthesis of novel 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines using the Weinreb Amide group is developed. The cyclization of 4-dimethylamino-1,3-diaza-1,3-butadiene having N-protecting groups (Boc) with N-methoxy-N-methylacrylAmide gives 6-unsubstituted 4-dimethylamino-2-phenyltetrahydropyrimidine, which is a synthetic intermediate for 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines. The transformation of the Weinreb Amide group to an acyl group via substitution reaction using organolithium reagents, following the elimination of a dimethylamino group using MeI proceeds smoothly, affording 4,6-unsubstituted 5-acyl-2-phenyldihydropyrimidines in good overall yield. The N-protecting group can be easily removed to obtain N-unsubstituted dihydropyrimidines as a mixture of tautomers, and their tautomeric behaviors were analyzed by 1H NMR spectroscopy.
