7451-73-2Relevant articles and documents
Visible-Light Mediated Tryptophan Modification in Oligopeptides Employing Acylsilanes
Reimler, Jannik,Studer, Armido
, p. 15392 - 15395 (2021/10/04)
A method for the selective tryptophan modification and labelling of tryptophan-containing peptides is described. Photoirradiation of acylsilanes generates reactive siloxycarbenes which undergo H?N-insertion into the indole moiety of tryptophan to give stable silyl protected hemiaminals. This method is successfully applied to chemically modify various tryptophan containing oligopeptides. The method enables the selective introduction of alkynes to peptides that are eligible for further alkyne-azide click chemistry. In addition, the dansyl fluorophore can be conjugated to a peptide using this approach.
Water-Tolerant and Atom Economical Amide Bond Formation by Metal-Substituted Polyoxometalate Catalysts
De Azambuja, Francisco,Parac-Vogt, Tatjana N.
, p. 10245 - 10252 (2019/11/03)
A simple, safe, and inexpensive amide bond formation directly from nonactivated carboxylic acids and free amines is presented in this work. Readily available Zr(IV)- and Hf(IV)-substituted polyoxometalates (POM) are shown to be catalysts for the amide bond formation reaction under mild conditions, low catalyst loading, and without the use of water scavengers, dry solvents, additives for facilitating the amine attack, or specialized experimental setups commonly employed to remove water. Detailed mechanistic investigations revealed the key role of POM scaffolds which act as inorganic ligands to protect Zr(IV) and Hf(IV) Lewis acidic metals against hydrolysis and preserve their catalytic activity in amide bond formation reactions. The catalysts are compatible with a range of functional groups and heterocycles useful for medicinal, agrochemical, and material chemists. The robustness of the Lewis acid-POM complexes is further supported by the catalyst reuse without loss of activity. This prolific combination of Zr(IV)/Hf(IV) and POMs inaugurates a powerful class of catalysts for the amide bond formation, which overcomes key limitations of previously established Zr(IV)/Hf(IV) salts and boron-based catalysts.
AGRICULTURAL CHEMICAL CONTAINING 2,5-DIKETOPIPERAZINE DERIVATIVE AS ACTIVE INGREDIENT
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Paragraph 0033, (2013/06/05)
Disclosed herein is an agricultural agent containing a 2,5-diketopiperazine derivative capable of controlling plant diseases and promoting plant growth or an agriculturally acceptable salt thereof as an active ingredient.
