peptide coupling order of reagents HATU2, PyAOP1,3, and HCTU4, PyClocK - Peptide coupling reagentsPDF reagents Peptide Coupling: Understanding Reagent Order and Function in Synthesis

Peptide coupling reagentsreview The `search_keyword` is "peptide coupling order of reagents". The `serp` and `Related searches` indicate a strong focus on peptide synthesis, specifically the reagents used for forming peptide bonds. The `Search intent` further confirms this by listing common coupling reagents and the general process.Compounds of the formula I are used as coupling reagentsin peptide synthesis ... The latter is extensively dried and several times suspended in hot ethyl acetate ... The dominant search intent appears to be understanding the types of reagents used in peptide coupling and potentially their roles or sequence in the reaction.

Here's a breakdown of the tiers:

Tier 1:

* search_keyword: peptide coupling order of reagents

* Core Concepts: Peptide coupling, coupling reagents, reagents, order

* Key Entities/Phrases: Peptide synthesis, coupling reaction, amide bond formation, carbodiimides (DCC, EDC), phosphonium salts (BOP, PyBOP), uronium salts (HATU, HBTU, HCTU)

* High-Relevance Phrases: "peptide coupling reagent," "coupling reagents," "amide bond formation," "peptide synthesis"

Tier 2:

* Supporting Concepts: Mechanism, additives, specific reagent classes (e.g., phosphonium, uronium), efficiency, stability, specific reagent names (PyAOP, PyClocK, DEPBT, PyBrOP, TATU, TBTU), CarboMAX, Ramage Linker, Rink Amide Linker, Fmoc-amino acids, C-terminus, N-terminus, aqueous media, epimerization, postsynthetic modification, MOFs.

* Common Variations: "peptide coupling mechanism," "peptide coupling reaction," "amide coupling reagents."

Tier 3:

* Less Relevant/Noisy: Specific patent numbers (US5166394A), overly specific chemical structures (Compounds of the formula I), Chinese characters, journal article authors/dates, "letter soup," "eco-friendly peptide synthesis" (unless directly tied to reagent choice), "monitoring of coupling," "coupling tests," "blog," "product guides2023年2月7日—In today's post, I'll describe a strategy that can increase the overall crude purity of an entirepeptidelibrary using two differentcouplingchemistries.."

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Peptide coupling is a fundamental process in peptide synthesis, involving the sequential joining of amino acids through the formation of amide bonds. The order of reagents in peptide coupling is crucial for achieving efficient and accurate synthesis, ensuring that the correct amino acid residues are linked in the desired sequence.Recent development in peptide coupling reagents While the term "order of reagents" might imply a strict step-by-step sequence for every reaction, in practice, it refers more to the strategic selection and introduction of specific coupling reagents and additives that activate the carboxylic acid of one amino acid (or peptide fragment) to react with the amine group of another.N,N'-Dicyclohexylcarbodiimide (DCC): DCC was one of the firstcoupling reagentsused inpeptidesynthesis. It is highly effective in promotingpeptidebond ... Understanding these reagents and their roles is paramount for successful peptide synthesis.

The Role of Coupling Reagents in Peptide Synthesis

At its core, peptide coupling involves activating the carboxyl group of an amino acid to make it more susceptible to nucleophilic attack by the amino group of another amino acid. This activation is typically facilitated by coupling reagents. These reagents transform the carboxyl group into a more reactive intermediate, such as an activated ester or an anhydride, which then readily forms the peptide bond. Without appropriate activation, the direct reaction between a carboxyl group and an amine group is slow and inefficient.

Common classes of peptide coupling reagents include:

* Carbodiimides: These were among the earliest and remain widely used. Examples include N,N'-Dicyclohexylcarbodiimide (DCC) and N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC)The most important areHATU2, PyAOP1,3, and HCTU4, PyClocK, which in the presence of base convert carboxylic acids to the corresponding OAt and O-6-ClBt esters .... Carbodiimides facilitate coupling by forming an O-acylisourea intermediate, which is highly reactiveRace out to eco-friendly peptide synthesis. However, they can sometimes lead to side reactions like racemization or the formation of insoluble byproducts (e.g., dicyclohexylurea from DCC)Coupling reagents | Product Guides.

* Phosphonium Salts: Reagents like Benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBOP) and (Benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) are effectivePeptide Coupling Reagents Guide. They typically work by forming an activated ester with the carboxylic acid, often in the presence of a base like N,N-Diisopropylethylamine (DIPEA).

* Uronium/Aminium Salts: This class includes some of the most potent and widely used reagents today, such as O-(Benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU), O-(7-Azabenzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU), and (1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxid hexafluorophosphate) (HCTU).作者：H Hintz·2014·被引用次数：77—The suitability of fourpeptide coupling reagentsfor postsynthetic modification (PSM) of amino-tagged metal–organic frameworks (MOFs) with carboxylic acids ... These reagents are known for their speed and efficiency, often minimizing racemizationPeptide synthesis. They form highly reactive O-acylisourea intermediates or activated esters.

Strategic Reagent Selection and Order of Addition

While there isn't a single universal "order of reagents" that applies to every scenario, the general strategy in peptide coupling involves:

1.Coupling reagentsare mainly used in the synthesis of amides and peptides but also of esters and other derivatives. Activation of the Carboxylic Acid: The coupling reagent is typically added to the protected amino acid (or peptide fragment) that possesses the free carboxyl groupCouplingTests. Monitoring of thecouplingsteps is critical in successfulpeptidesynthesis and a number of qualitative tests have been developed.. Often, an additive like 1-Hydroxybenzotriazole (HOBt) or its safer analog, 1-Hydroxy-7-azabenzotriazole (HOAt), is included. These additives react with the activated intermediate (e.g.US5166394A - Coupling reagent for peptide synthesis, O-acylisourea) to form a more stable, yet still reactive, activated ester. This step is crucial for increasing reaction efficiency and suppressing racemization.

2The uronium (O-derivs.) forms ofpeptide coupling reagents, HBTU and HATU (I; X = CH for HBTU, X = N for HATU), have been synthesized by substituting the .... Addition of the Nucleophile: Once the activated species is formed, the amino acid (or peptide fragment) with the free amine group is introduced. This amine then attacks the activated carboxyl group, forming the new amide (peptide) bond.

3. Base and Solvent: A base, such as DIPEA or N-methylmorpholine (NMM), is often included to deprotonate the amine group, making it a stronger nucleophile, and to neutralize any acids generated during the reaction. The choice of solvent is also critical, with common options including N,N-Dimethylformamide (DMF), N-Methyl-2-pyrrolidone (NMP), or dichloromethane (DCM), depending on the specific reagents and solubility of the reactants.

The "order" thus refers to the sequence of adding the activated amino acid/peptide, the incoming amino acid/peptide, the coupling reagent, any additives, and the base. For instance, in solid-phase peptide synthesis (SPPS), the growing peptide chain is attached to a solid support, and the activated amino acid is typically added to the resin-bound peptide.

Factors Influencing Reagent Choice and Application

The selection of a specific peptide coupling reagent depends on several factors, including:

* Efficiency and Yield: Some reagents offer higher yields and faster reaction times. HATU and HCTU are generally considered very potent and fast.

* Racemization Suppression: For sensitive amino acids or long peptide sequences, minimizing epimerization (loss of stereochemical integrity) is critical. Reagents like HATU, often in conjunction with HOAt, are favored for this purposeUS5166394A - Coupling reagent for peptide synthesis.

* Solubility and Byproducts: Reagents like DCC produce insoluble dicyclohexylurea, which can be filtered off but might complicate purificationPeptide Coupling Reagents. EDC produces a water-soluble urea byproduct, often preferred for solution-phase synthesis or when easy workup is desired.

* Cost and Availability: For large-scale synthesis, the cost and availability of reagents are significant considerations.Coupling Reagents

* Specific Reaction Conditions: Some coupling methodologies are optimized for specific conditions, such as elevated temperatures (e.g., CarboMAX) or aqueous media.

In summary, while there isn't a rigid "order of reagents" in the sense of a fixed list of steps applicable everywhere, the strategic introduction of coupling reagents, additives, and nucleophiles is fundamental to successful peptide coupling.4天前—To couple the Fmoc-amino acids, some auxiliary additives —coupling reagents— are usually needed. In this work, the combination of a water ... The careful selection and judicious application of these components ensure the efficient and accurate construction of peptide chains.