Reay, Alan James orcid.org/0000-0003-3118-6146, Hammarback, Lars Anders, Bray, Joshua Thomas William orcid.org/0000-0003-2384-9675 et al. (4 more authors) (2017) Mild and Regioselective Pd(OAc)2-Catalyzed C–H Arylation of Tryptophans by [ArN2]X, Promoted by Tosic Acid. ACS Catalysis. pp. 5174-5179. ISSN 2155-5435
Abstract
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 under 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 indicates that the reaction is operating homogeneously, although Pd nanoparticles are formed during substrate turnover. The impact 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 employing [ArN2]BF4 salts with Pd(OAc)2. Pd(OTs)2(MeCN)2 was found to be a superior precatalyst (confirmed by kinetic studies) to Pd(OAc)2.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017. The Author(s). |
Keywords: | aryldiazonium salt,chirality,cross-coupling,directing group,heteroarene,palladium,regioselectivity |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Funding Information: | Funder Grant number EUROPEAN COMMISSION 115360 |
Depositing User: | Pure (York) |
Date Deposited: | 20 Jun 2017 09:45 |
Last Modified: | 19 Mar 2025 00:07 |
Published Version: | https://doi.org/10.1021/acscatal.6b03121 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1021/acscatal.6b03121 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:117925 |
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