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Pawlas J, André C, Rasmussen JH, Ludemann-Hombourger O. Brønsted Acid-Lewis Acid (BA-LA) Induced Final Deprotection/Peptide Resin Cleavage in Fmoc/ t-Bu Solid-Phase Peptide Synthesis: HCl/FeCl 3 and AcOH/FeCl 3 as Viable PFAS-Free Alternatives for TFA. Org Lett 2024; 26:6787-6791. [PMID: 39073347 DOI: 10.1021/acs.orglett.4c02569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The widely used Fmoc/t-Bu solid-phase peptide synthesis (SPPS) is hampered by relying on corrosive, per/polyfluoroalkyl substance (PFAS) classified trifluoroacetic acid (TFA) as a universal protecting group (PG) removal/resin cleavage reagent. We report that suitable combinations of Brønsted acids (BAs) and Lewis acids (LAs) such as HCl/FeCl3 and AcOH/FeCl3 constitute viable alternatives for TFA as PFAS-free cleavage agents. Using water miscible dimethyl carbonate (DMC) and acetonitrile (MeCN) as solvents enabled diluting cleavage mixtures with suitable aqueous solutions, allowing for direct use in purification in which removal of >99.99% iron from an HCl/FeCl3 induced cleavage was demonstrated.
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Affiliation(s)
- Jan Pawlas
- PolyPeptide, Limhamnsvägen 108, PO Box 30089, 20061 Limhamn, Sweden
| | - Christophe André
- PolyPeptide, Bioparc 3, 850 Bd Sebastien Brant, 67400 Illkirch, France
| | - Jon H Rasmussen
- PolyPeptide, Limhamnsvägen 108, PO Box 30089, 20061 Limhamn, Sweden
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2
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Ryan MR, Lynch D, Collins SG, Maguire AR. Selective Thermal Deprotection of N-Boc Protected Amines in Continuous Flow. Org Process Res Dev 2024; 28:1946-1963. [PMID: 38783851 PMCID: PMC11110071 DOI: 10.1021/acs.oprd.3c00498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/06/2024] [Accepted: 03/28/2024] [Indexed: 05/25/2024]
Abstract
Thermal N-Boc deprotection of a range of amines is readily effected in continuous flow, in the absence of an acid catalyst. While the optimum results were obtained in methanol or trifluoroethanol, deprotection can be effected in a range of solvents of different polarities. Sequential selective deprotection of N-Boc groups has been demonstrated through temperature control, as exemplified by effective removal of an aryl N-Boc group in the presence of an alkyl N-Boc group. As a proof of principle, a telescoped sequence involving selective deprotection of an aryl N-Boc group from 9h followed by benzoylation and deprotection of the remaining alkyl N-Boc group to form amide 13 proved successful.
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Affiliation(s)
- Michelle-Rose Ryan
- School
of Chemistry, Analytical and Biological Chemistry Research Facility, University College Cork, Cork T12 YN60, Ireland
| | - Denis Lynch
- School
of Chemistry, Analytical and Biological Chemistry Research Facility, University College Cork, Cork T12 YN60, Ireland
| | - Stuart G. Collins
- School
of Chemistry, Analytical and Biological Chemistry Research Facility,
SSPC, The SFI Research Centre for Pharmaceuticals, University College Cork, Cork T12 YN60, Ireland
| | - Anita R. Maguire
- School
of Chemistry and School of Pharmacy, Analytical and Biological Chemistry
Research Facility, SSPC, The SFI Research Centre for Pharmaceuticals, University College Cork, Cork T12 YN60, Ireland
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Sah P, Gond AK, Saini G, Kapur M. A Sequential Transition Metal and Organocatalytic Approach to the Enantioselective Synthesis of C2-Spiroindoline Systems. Org Lett 2023; 25:9170-9175. [PMID: 38100382 DOI: 10.1021/acs.orglett.3c03716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
We report herein an organocatalyzed enantioselective spirocyclization strategy to access valuable C2-spiroindoline scaffolds bearing a quaternary stereocenter via an aza-Michael addition reaction, wherein the acid additive plays the role of dual functionality. The substrates for this key step were put together by an exo-selective, Pd-catalyzed γ-arylation of silyldienol ethers of the corresponding cyclohexenones. A close alliance between a low catalyst loading and a slow reaction rate yields C2-spiroindolines with good enantioselectivity.
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Affiliation(s)
- Pooja Sah
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, 462066, MP, India
| | - Aakash Kumar Gond
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, 462066, MP, India
| | - Gaurav Saini
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, 462066, MP, India
| | - Manmohan Kapur
- Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, 462066, MP, India
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Nakahara H, Sennari G, Noguchi Y, Hirose T, Sunazuka T. Development of a nitrogen-bound hydrophobic auxiliary: application to solid/hydrophobic-tag relay synthesis of calpinactam. Chem Sci 2023; 14:6882-6889. [PMID: 37389244 PMCID: PMC10306108 DOI: 10.1039/d3sc01432k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 04/28/2023] [Indexed: 07/01/2023] Open
Abstract
In the last couple of decades, technologies and strategies for peptide synthesis have advanced rapidly. Although solid-phase peptide synthesis (SPPS) and liquid-phase peptide synthesis (LPPS) have contributed significantly to the development of the field, there have been remaining challenges for C-terminal modifications of peptide compounds in SPPS and LPPS. Orthogonal to the current standard approach that relies on installation of a carrier molecule at the C-terminus of amino acids, we developed a new hydrophobic-tag carbonate reagent which facilitated robust preparation of nitrogen-tag-supported peptide compounds. This auxiliary was easily installed on a variety of amino acids including oligopeptides that have a broad range of noncanonical residues, allowing simple purification of the products by crystallization and filtration. We demonstrated a de novo solid/hydrophobic-tag relay synthesis (STRS) strategy using the nitrogen-bound auxiliary for total synthesis of calpinactam.
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Affiliation(s)
- Hiroki Nakahara
- Ōmura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University 5-9-1 Shirokane, Minato-ku Tokyo 108-8641 Japan
| | - Goh Sennari
- Ōmura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University 5-9-1 Shirokane, Minato-ku Tokyo 108-8641 Japan
| | - Yoshihiko Noguchi
- Ōmura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University 5-9-1 Shirokane, Minato-ku Tokyo 108-8641 Japan
| | - Tomoyasu Hirose
- Ōmura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University 5-9-1 Shirokane, Minato-ku Tokyo 108-8641 Japan
| | - Toshiaki Sunazuka
- Ōmura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University 5-9-1 Shirokane, Minato-ku Tokyo 108-8641 Japan
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A Brønsted Acidic Deep Eutectic Solvent for N-Boc Deprotection. Catalysts 2022. [DOI: 10.3390/catal12111480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The tert-butyloxycarbonyl (Boc) group is one of the most widely used amine-protecting groups in multistep reactions in synthetic organic chemistry as well as in peptide synthesis. Traditional methods to remove the Boc group have disadvantages in terms of high acidity, the use of expensive reagents, excessive amounts of catalysts and harmful solvents as well as high temperatures, making them environmentally unsustainable. Therefore, more efforts must be stepwise tightened to make Boc removal practical, clean, and minimize any potential impact. We describe an efficient and sustainable method for N-Boc deprotection by means of a choline chloride/p-toluenesulfonic acid deep eutectic solvent (DES), which is used as a reaction medium plus catalyst. The adopted conditions allow the deprotection of a wide variety of N-Boc derivatives in excellent yields. The strategy has found advantages in greening, simplicity, and short reaction times, resulting in a useful alternative to standard methods.
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Yang Y, Zhang T, Xing D. Single 808 nm near-infrared-triggered multifunctional upconverting phototheranostic nanocomposite for imaging-guided high-efficiency treatment of tumors. JOURNAL OF BIOPHOTONICS 2021; 14:e202100134. [PMID: 34115430 DOI: 10.1002/jbio.202100134] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 06/12/2023]
Abstract
Multifunctional phototheranostic nanocomposites are promising for early diagnosis and precision therapy of cancer. Aim to enhance their accuracy and efficiency, in this study, we develop a single-laser excited activatable phototheranostic nanocomposite (UCNPs-D-MQ): 808 nm-excited upconverting nanoparticles (UCNPs) as the matrix programmed assembly with amphipathic compound DSPE-PEG-COOH, a near-infrared absorbing polymer DPP and the pro-photosensitizer MBQB. Upon endocytosed by cancer cells and excited by the 808 nm laser, UCNPs-D-MQ could produce high-yield reactive oxygen species (ROS) as the results of singlet oxygen generation from transferring to methylene blue, GSH depletion and ROS generation from photoactivation. It was proven both in vitro and in vivo that the nanocomposites exhibits remarkable therapeutic efficacy as well as minimal photodamage to normal cells. These results reveal UCNPs-D-MQ as a robust theranostic agent for tumor phototherapy.
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Affiliation(s)
- Yang Yang
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China
- College of Biophotonics, South China Normal University, Guangzhou, China
| | - Tao Zhang
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China
- College of Biophotonics, South China Normal University, Guangzhou, China
| | - Da Xing
- MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China
- College of Biophotonics, South China Normal University, Guangzhou, China
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Dolai G, Giri RS, Roy S, Mandal B. Crystal structure and supramolecular arrangement of heterochiral tripeptides. Pept Sci (Hoboken) 2021. [DOI: 10.1002/pep2.24229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Gobinda Dolai
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Assam India
| | - Rajat Subhra Giri
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Assam India
| | - Sayanta Roy
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Assam India
| | - Bhubaneswar Mandal
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Assam India
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Roy S, Giri RS, Dolai G, Mandal B. Role of side-chain and chirality of the amino acids on the supramolecular assemblies of dipeptides. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128877] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Giri RS, Pal S, Roy S, Dolai G, Manne SR, Paul S, Mandal B. Nanostructures from protected L/L and D/L amino acid containing dipeptides. Pept Sci (Hoboken) 2020. [DOI: 10.1002/pep2.24176] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Rajat Subhra Giri
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Guwahati India
| | - Saikat Pal
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati India
| | - Sayanta Roy
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Guwahati India
| | - Gobinda Dolai
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Guwahati India
| | - Srinivasa Rao Manne
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Guwahati India
| | - Sandip Paul
- Department of Chemistry Indian Institute of Technology Guwahati Guwahati India
| | - Bhubaneswar Mandal
- Department of Chemistry, Laboratory of Peptide and Amyloid Research Indian Institute of Technology Guwahati Guwahati India
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