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Upstream product

• 5720-07-0 4-methoxyphenylboronic acid 
• 2824-57-9 N-acetyl-L-tryptophan methyl ester 
• 1604-49-5 methyl (2S)-3-(1H-indol-3-yl)-2-(trifluoroacetamido)propanoate 
• 459-64-3 4-methoxybenzenediazonium tetrafluoroborate 
• 696-62-8 para-iodoanisole 

Relevant academic research and scientific papers

Unified mild reaction conditions for C2-selective Pd-catalysed tryptophan arylation, including tryptophan-containing peptides

Pd-mediated C-H bond functionalisation protocols have been designed and developed on tryptophan derivatives and tryptophan-containing peptides. The examination of different arylation reactions (three sets of different conditions A-C), all of which are notable for their low temperatures (≤40°C), allowed identification of unified and complementary synthetic approaches toward a series of functionalised tryptophan-containing products. Tryptophan-containing peptides demonstrated to be susceptible to aromatic oxidation were successfully and selectively modified through the application of diaryliodonium salts in good yields.

Pd-Oxazolone complexes conjugated to an engineered enzyme: improving fluorescence and catalytic properties

Different Pd-complexes containing orthometallated push-pull oxazolones were inserted by supramolecular Pd-amino acid coordination on two genetically engineered modified variants of the thermoalkalophilicGeobacillus thermocatenolatuslipase (GTL). Pd-lipase conjugation was performed on the solid phase in the previously immobilized form of GTL under mild conditions, and soluble conjugated Pd-GTL complexes were obtained by simply desorbing by washing with an acetonitrile aqueous solution. Three different Pd complexes were incorporated into two different genetically modified enzyme variants, one containing all the natural cysteine residues changed to serine residues, and another variant including an additional Cys mutation directly in the catalytic serine (Ser114Cys). The new Pd-enzyme conjugates were fluorescent even at ppm concentrations, while under the same conditions free Pd complexes did not show fluorescence at all. The Pd conjugation with the enzyme extremely increases the catalytic profile of the corresponding Pd complex from 200 to almost 1000-fold in the hydrogenation of arenes in aqueous media, achieving in the case of GTL conjugated with orthopalladated4aan outstanding TOF value of 27?428 min?1. Also the applicability of GTL-C114 conjugated with orthopalladated4bin a site-selective C-H activation reaction under mild conditions has been demonstrated. Therefore, the Pd incorporation into the enzyme produces a highly stable conjugate, and improves remarkably the catalytic activity and selectivity, as well as the fluorescence intensity, of the Pd complexes.

Site-selective modification of tryptophan and protein tryptophan residues through PdNP bionanohybrid-catalysed C-H activation in aqueous media

Herein we report for the first time the site-selective C-H bond arylation of tryptophan and tryptophan residues in proteins in aqueous media at room temperature by using a PdNP bionanohybrid as a heterogeneous catalyst. The reaction proceeds using a stable aryldiazonium salt without a base.

Mild and Regioselective Pd(OAc)2-Catalyzed C-H Arylation of Tryptophans by [ArN2]X, Promoted by Tosic Acid

A regioselective Pd-mediated C-H bond arylation methodology for tryptophans, utilizing stable aryldiazonium salts, affords C2-arylated tryptophan derivatives, in several cases quantitatively. The reactions proceed in air, without base, and at room temperature in EtOAc. The synthetic methodology has been evaluated and compared against other tryptophan derivative arylation methods using the CHEM21 green chemistry toolkit. The behavior of the Pd catalyst species has been probed in preliminary mechanistic studies, which indicate that the reaction is operating homogeneously, although Pd nanoparticles are formed during substrate turnover. The effects of these higher order Pd species on catalysis, under the reaction conditions examined, appear to be minimal: e.g., acting as a Pd reservoir in the latter stages of substrate turnover or as a moribund form (derived from catalyst deactivation). We have determined that TsOH shortens the induction period observed when [ArN2]BF4 salts are employed with Pd(OAc)2. Pd(OTs)2(MeCN)2 was found to be a superior precatalyst (confirmed by kinetic studies) in comparison to Pd(OAc)2.

A mild and selective Pd-mediated methodology for the synthesis of highly fluorescent 2-arylated tryptophans and tryptophan-containing peptides: A catalytic role for Pd0 nanoparticles?

A Pd-mediated direct C-H bond functionalisation of tryptophan has been developed, both as a single amino acid residue and within peptides. Important mechanistic insight into this process has been gained by characterising a Pd catalytically competent nanoparticle phase which evolves during the early stages of reaction. The Royal Society of Chemistry.

Postsynthetic modification of peptides: Chemoselective C-arylation of tryptophan residues

Born to be mild : The general, direct and selective C2 arylation of native Trp-containing peptides can be achieved by palladium-catalyzed C-H activation with aryl iodides in water, under microwave irradiation for a short time (see scheme). Under these mild conditions, the structural and stereochemical integrity of peptides is preserved.