p-Nitrobenzyloxycarbonyl (pNZ) as Temporary Na-Protecting Group for Mild Solid-Phase Peptide Synthesis. Avoiding Diketopiperazine and Aspartimide Formation

p-Nitrobenzyloxycarbonyl was used as temporary protecting group for the -amino function in solid-phase peptide synthesis. The corresponding derivatives are solids, easy to be synthesized, and perform well in the solid-phase mode. pNZ is removed in practical neutral conditions in the presence of catalytic amounts of acid. They are orthogonal with the most common protecting groups used in peptide chemistry. They are specially useful in combination with Fmoc chemistry to overcome those side reactions associated with the used of the piperidine such DKP and aspartiimide formation. The flexibility of pNZ can be very useful for the preparation of libraries of small organic molecules

Fmoc-2-Mercaptobenzothiazole (MBT), for the Introduction of the Fmoc Moiety Free of Side-Reactions

A double side-reaction, consisting in the formation of Fmoc--Ala-OH and Fmoc--Ala-AA-OH, during the preparation of Fmoc protected amino acids (Fmoc-AA-OH) with Fmoc-OSu is discussed. Furthermore, the new Fmoc-2-MBT reagent is proposed for avoiding these side-reactions as well as the formation of the Fmoc-dipeptides (Fmoc-AA-AA-OH) and even tripeptides, which is another important side-reaction when chloroformates such as Fmoc-Cl is used for the protection of the -amino function of the amino acids

Characterisation of IL-23 receptor antagonists and disease relevant mutants using fluorescent probes

Association of single nucleotide polymorphisms in the IL-23 receptor with several auto-inflammatory diseases, led to the heterodimeric receptor and its cytokine-ligand IL-23, becoming important drug targets. Successful antibody-based therapies directed against the cytokine have been licenced and a class of small peptide antagonists of the receptor have entered clinical trials. These peptide antagonists may offer therapeutic advantages over existing anti-IL-23 therapies, but little is known about their molecular pharmacology. In this study, we use a fluorescent version of IL-23 to characterise antagonists of the full-length receptor expressed by living cells using a NanoBRET competition assay. We then develop a cyclic peptide fluorescent probe, specific to the IL23p19:IL23R interface and use this molecule to characterise further receptor antagonists. Finally, we use the assays to study the immunocompromising C115Y IL23R mutation, demonstrating that the mechanism of action is a disruption of the binding epitope for IL23p19

One-pot homologation of boronic acids

This work was supported by the Engineering and Physical Sciences Research Council (EPSRC).Formal homologation of sp2-hybridized boronic acids is achieved via cross-coupling of boronic acids with conjunctive haloaryl BMIDA components in the presence of a suitably balanced basic phase. The utility of this approach to provide a platform for diversity-oriented synthesis in discovery medicinal chemistry is demonstrated in the context of the synthesis of a series of analogues of a BET bromodomain inhibitor.Publisher PDFPeer reviewe

Identification of KLHDC2 as an efficient proximity-induced degrader of K-RAS, STK33, β-catenin, and FoxP3

Targeted protein degradation (TPD), induced by enforcing target proximity to an E3 ubiquitin ligase using small molecules has become an important drug discovery approach for targeting previously undruggable disease-causing proteins. However, out of over 600 E3 ligases encoded by the human genome, just over 10 E3 ligases are currently utilized for TPD. Here, using the affinity-directed protein missile (AdPROM) system, in which an anti-GFP nanobody was linked to an E3 ligase, we screened over 30 E3 ligases for their ability to degrade 4 target proteins, K-RAS, STK33, β-catenin, and FoxP3, which were endogenously GFP-tagged. Several new E3 ligases, including CUL2 diGly receptor KLHDC2, emerged as effective degraders, suggesting that these E3 ligases can be taken forward for the development of small-molecule degraders, such as proteolysis targeting chimeras (PROTACs). As a proof of concept, we demonstrate that a KLHDC2-recruiting peptide-based PROTAC connected to chloroalkane is capable of degrading HALO-GFP protein in cells

Jugoslavija u međunarodnoj trgovini ribom, ribljim proizvodima i prerađevinama

Sulfonamides are profoundly important in pharmaceutical design. C–N cross-coupling of sulfonamides is an effective method for fragment coupling and structure–activity relationship (SAR) mining. However, cross-coupling of the important <i>N</i>-arylsulfonamide pharmacophore has been notably unsuccessful. Here, we present a solution to this problem via oxidative Cu-catalysis (Chan–Lam cross-coupling). Mechanistic insight has allowed the discovery and refinement of an effective cationic Cu catalyst to facilitate the practical and scalable Chan–Lam <i>N</i>-arylation of primary and secondary <i>N</i>-arylsulfonamides at room temperature. We also demonstrate utility in the large scale synthesis of a key intermediate to a clinical hepatitis C virus treatment

New Protecting Groups for the Synthesis of Complex Peptides

[eng]The increasing importance of peptides as drugs creates the necessity of new methodologies for the synthesis of complex peptides. This PhD thesis has been focused on the development of new protecting groups (including new linkers) for peptide synthesis. The work done has solved several problems in peptide synthesis making it more versatile. These are some of the results obtained: - The removal conditions of the pNZ group as α-amino and Orn and Lys side chain protector have been optimized. These optimized conditions make pNZ orthogonal to the most used protecting groups in the Fmoc/tBu solid phase peptide synthesis strategy (Fmoc, Boc and Alloc) and minimize its most important side reactions such as formation of diketopiperazines, aspartimides and removal of the α-Fmoc group. The use of the pNZ group allows also the synthesis of complex and biologically interesting peptides such as the antitumoral peptide Kahalalide F. - A new protecting agent, the Fmoc-2-mercaptobenzothiazole (Fmoc-MBT), has been developed. It prevents side reactions in the synthesis of Fmoc-amino acids. New protecting groups developed: - p-Nitromandelic linker (pNM): it is useful for the synthesis of peptides and depsipeptides using the Boc/Bn strategy. - Backbone protectors (3,4-ethylenedioxythenyl (EDOTn) and 1-methyl-3-indolylmethyl (MIM)): they improve some of the poperties of the present backbone protectors such as their difficult elimination and steric hindrance. - Phenyl-EDOTn derivatives as super acid labile carboxylic acid protecting groups. - 1,2-dimethylindole-3-sulfonyl (MIS) as a protector of the side chain of arginine: it is much more acid labile than the present protecting groups and it is compatible with tryptophan containing peptides.[cat] Els pèptids estan cobrant una importància creixent com a fàrmacs i això fa necessàries noves eines per a la seva síntesi. Aquesta Tesi Doctoral se centra en el desenvolupament de grups protectors per a la síntesi de pèptids complexos. Aquests protectors poden ser molècules petites lliures o unides a suports polimèrics. En el darrer cas s'anomenen espaïadors bifuncionals. L'impuls decisiu per a la química de pèptids va ser el desenvolupament de la metodologia de fase sòlida per part de Merrifield als anys 60. L'estratègia original de Merrifield es denomina Boc/Bn (tert-butiloxicarbonil/benzil). En ella el grup α-amino dels aminoàcids està protegit pel grup Boc, làbil a àcid trifluoroacètic (TFA), i les cadenes laterals dels aminoàicds estan protegides amb protectors de tipus benzílic, eliminats al escindir el pèptid de la resina amb àcids forts, en general HF. Actualment, però, l'estratègia més usada es la Fmoc/tBu (9- fluorenilmetoxicarbonil/tert-butil) ón el grup α-amino es protegeix amb el grup Fmoc, làbil a bases, i les cadenes laterals amb grups de tipus tert-butil, eliminats al escindir el pèptid de la resina amb TFA. El treball realitzat en aquesta Tesi ha permès resoldre alguns dels problemes actuals en síntesi de pèptids aconseguint fer-la més versàtil. En concret: - S'han millorat les condicions d'eliminació del grup pNZ com a protector d'α-amino i de les cadenes laterals d'Orn i Lys. Aquestes condicions el fan ortogonal als protectors més usats en síntesi de pèptids (Boc, Fmoc y Alloc) i minimitzen les reaccions secundàries associades a la síntesi de pèptids en fase sòlida mitjantçant l'estratègia Fmoc/tBu, com la formació de dicetopiperazines, aspartimides i l'eliminació del grup α-Fmoc. L´ús del prup pNZ permet a més l'accés a estructures peptídiques complexes així com el desenvolupament de noves estratègies de síntesi de pèptids d'elevat interès biològic com el pèptid antitumoral Kahalalide F. - S'ha desenvolupat un nou agent protector, el Fmoc-2-mercaptobenzotiazole (Fmoc-MBT), que permet la síntesi de Fmoc-aminoàcids evitant les reaccions secundàries associades als reactius actuals. Nous protectors desenvolupats: - Espaïador bifuncional p-nitromandèlic (pNM): és útil per a la síntesi de pèptids i depsipèptids mitjantçant química Boc/Bn. - Protectors d'amides de l'esquelet peptídic (3,4-etilendioxi-2-tenil (EDOTn) y 1-metil-3- indolilmetil (MIM)): milloren algunes de les propietats dels protectors actuals com la seva difícil eliminació i el seu impediment estèric. - Derivats del fenil-EDOTn com a grups protectors d'àcids carboxílics molt làbils a medi àcid (estàndar i espaïadors bifuncionals). - 1,2-dimetilindole-3-sulfonil (MIS) com a protector de la cadena lateral de l'arginina molt més làbil a medi àcid que els protectors actuals i compatible amb pèptids que contenen triptòfan.[spa] Los péptidos están cobrando cada vez más importancia como fármacos y esto hace necesarias nuevas herramientas para su síntesis. La presente Tesis Doctoral se centra en el desarrollo de grupos protectores para síntesis de péptidos complejos. Estos protectores pueden se moléculas pequeñas o unidas a soportes poliméricos. En este último caso se denominan espaciadores bifuncionales. El impulso decisivo para la química de péptidos fue el desarrollo de la metodología de fase sólida por parte de Merrifield en los años 60. La estrategia original de Merrifield, se denomina Boc/Bn (tert-butiloxicarbonilo/benzilo). En ella el grupo α-amino de los amino ácidos está protegido con el grupo Boc, lábil a ácido trifluoroacético (TFA), y las cadenas laterales de los amino ácidos están en general protegidas con protectores de tipo benzílico, eliminados al escindir el péptido de la resina con ácidos fuertes, generalmente HF. Sin embargo, en la actualidad, la estrategia más usada es la Fmoc/tBu (9-fluorenilmetoxicarbonilo/tert-butilo) , en la cual el grupo α-amino se protege con el grupo Fmoc, lábil a bases y las cadenas laterales con grupos de tipo tert-butilo, eliminados al escindir el péptido de la resina con TFA. El trabajo realizado en la presente Tesis ha permitido resolver algunos de los problemas actuales en síntesis de péptidos haciéndola mas versátil. Concretamente: - Se han mejorado las condiciones de eliminación del grupo pNZ como protector del α-amino y de las cadenas laterales de Orn y Lys. Estas condiciones lo hacen ortogonal a los protectores más usados en síntesis de péptidos (Boc, Fmoc y Alloc) y minimizan reacciones secundarias asociadas a la síntesis de péptidos en fase sólida mediante la estrategia Fmoc/tBu, como la formación de dicetopiperazinas, aspartimidas y la eliminación del grupo α-Fmoc. El uso del grupo pNZ permite además el acceso a estructuras peptídicas complejas así como el desarrollo de nuevas estrategias de síntesis de péptidos de elevado interés biológico como el péptido antitumoral Kahalalide F. - Se ha desarrollado un nuevo agente protector, el Fmoc-2-mercaptobenzotiazol (Fmoc-MBT), que permite la síntesis de Fmoc-amino ácidos evitando las reacciones secundarias asociadas a los reactivos actuales. Nuevos grupos protectores desarrollados: - Espaciador bifuncional p-nitromandélico (pNM): es útil para la síntesis de péptidos y depsipéptidos mediante química Boc/Bn. - Protectores de amidas del esqueleto peptídico (3,4-etilendioxi-2-tenil (EDOTn) y 1-metil-3- indolilmetil (MIM): mejoran algunas de las propiedades de los protectores actuales, com su difícil eliminación y su impedimento estérico. - Derivados del fenil-EDOTn como grupos protectores de ácidos carboxílicos muy lábiles a medio ácido (estándar y espaciadores bifuncionales). - 1,2-dimetilindole-3-sulfonil (MIS) como protecor de la cadena lateral de la arginina mucho más lábil a medio ácido que los protectores actuales y compatible con péptidos que contienen triptófano