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HATU is commonly encountered in amine acylation reactions (i.e., amide formation). Such reactions are typically performed in two distinct reaction steps: (1) reaction of a carboxylic acid with HATU to form the OAt-active ester; then (2) addition of the nucleophile (amine) to the active ester solution to afford the acylated product.
TCFH itself is a common reagent used in the preparation of uronium and guanidinium salts used for amide bond formation and peptide synthesis, such as HATU. [3] [4] [5]Amide bond formation with TCFH can be performed in a wide range of organic solvents, most commonly acetonitrile, but also water [6] and in the solid state. [7]
1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC, EDAC or EDCI) is a water-soluble carbodiimide usually handled as the hydrochloride. [1] It is typically employed in the 4.0-6.0 pH range. It is generally used as a carboxyl activating agent for the coupling of primary amines to yield amide bonds.
It is commonly used as the hindered base in amide coupling reactions between a carboxylic acid (typically activated, for example, as an acid chloride, as illustrated below) and a nucleophilic amine. [5] As DIPEA is hindered and poorly nucleophilic, it does not compete with the nucleophilic amine in the coupling reaction.
The activated intermediate species attacked by the amine during aminolysis is the HOBt ester. To create the HOBt ester, the carboxyl group of the acid attacks the imide carbonyl carbon of HBTU. Subsequently, the displaced anionic benzotriazole N-oxide attacks of the acid carbonyl, giving the tetramethyl urea byproduct and the activated ester.
The reaction was first described by Wolfgang Steglich in 1978. [1] It is an adaptation of an older method for the formation of amides by means of DCC (dicyclohexylcarbodiimide) and 1-hydroxybenzotriazole (HOBT). [2] [3] Steglich overview. This reaction generally takes place at room temperature. A variety of polar aprotic solvents can be used. [4]
A common way to synthesize an NHS-activated acid is to mix NHS with the desired carboxylic acid and a small amount of an organic base in an anhydrous solvent. A coupling reagent such as dicyclohexylcarbodiimide (DCC) or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) is then added to form a highly reactive activated acid intermediate.
PyAOP ((7-Azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate) is a reagent used to prepare amides from carboxylic acids and amines in the context of peptide synthesis. [1] It can be prepared from 1-hydroxy-7-azabenzotriazole (HOAt) and a chlorophosphonium reagent under basic conditions. [ 2 ]