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Bartholomew GL, Kraus SL, Karas LJ, Carpaneto F, Bennett R, Sigman MS, Yeung CS, Sarpong R. 14N to 15N Isotopic Exchange of Nitrogen Heteroaromatics through Skeletal Editing. J Am Chem Soc 2024; 146:2950-2958. [PMID: 38286797 DOI: 10.1021/jacs.3c11515] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
The selective modification of nitrogen heteroaromatics enables the development of new chemical tools and accelerates drug discovery. While methods that focus on expanding or contracting the skeletal structures of heteroaromatics are emerging, methods for the direct exchange of single core atoms remain limited. Here, we present a method for 14N → 15N isotopic exchange for several aromatic nitrogen heterocycles. This nitrogen isotope transmutation occurs through activation of the heteroaromatic substrate by triflylation of a nitrogen atom, followed by a ring-opening/ring-closure sequence mediated by 15N-aspartate to effect the isotopic exchange of the nitrogen atom. Key to the success of this transformation is the formation of an isolable 15N-succinyl intermediate, which undergoes elimination to give the isotopically labeled heterocycle. These transformations occur under mild conditions in high chemical and isotopic yields.
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Affiliation(s)
- G Logan Bartholomew
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Samantha L Kraus
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Lucas J Karas
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Filippo Carpaneto
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
| | - Raffeal Bennett
- Discovery Analytical Research, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Matthew S Sigman
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
| | - Charles S Yeung
- Discovery Chemistry, Merck & Co., Inc., Boston, Massachusetts 02115, United States
| | - Richmond Sarpong
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, United States
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Lysak DH, Wolff WW, Soong R, Bermel W, Kupče ER, Jenne A, Biswas RG, Lane D, Gasmi-Seabrook G, Simpson A. Application of 15N-Edited 1H- 13C Correlation NMR Spectroscopy─Toward Fragment-Based Metabolite Identification and Screening via HCN Constructs. Anal Chem 2023; 95:11926-11933. [PMID: 37535003 DOI: 10.1021/acs.analchem.3c01362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
Many key building blocks of life contain nitrogen moieties. Despite the prevalence of nitrogen-containing metabolites in nature, 15N nuclei are seldom used in NMR-based metabolite assignment due to their low natural abundance and lack of comprehensive chemical shift databases. However, with advancements in isotope labeling strategies, 13C and 15N enriched metabolites are becoming more common in metabolomic studies. Simple multidimensional nuclear magnetic resonance (NMR) experiments that correlate 1H and 15N via single bond 1JNH or multiple bond 2-3JNH couplings using heteronuclear single quantum coherence (HSQC) or heteronuclear multiple bond coherence are well established and routinely applied for structure elucidation. However, a 1H-15N correlation spectrum of a metabolite mixture can be difficult to deconvolute, due to the lack of a 15N specific database. In order to bridge this gap, we present here a broadband 15N-edited 1H-13C HSQC NMR experiment that targets metabolites containing 15N moieties. Through this approach, nitrogen-containing metabolites, such as amino acids, nucleotide bases, and nucleosides, are identified based on their 13C, 1H, and 15N chemical shift information. This approach was tested and validated using a [15N, 13C] enriched Daphnia magna (water flea) metabolite extract, where the number of clearly resolved 15N-containing peaks increased from only 11 in a standard HSQC to 51 in the 15N-edited HSQC, and the number of obscured peaks decreased from 59 to just 7. The approach complements the current repertoire of NMR techniques for mixture deconvolution and holds considerable potential for targeted metabolite NMR in 15N, 13C enriched systems.
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Affiliation(s)
- Daniel H Lysak
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - William W Wolff
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Ronald Soong
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Wolfgang Bermel
- Bruker BioSpin GmbH, Rudolf-Plank-Str. 23, Ettlingen 76275, Germany
| | | | - Amy Jenne
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Rajshree Ghosh Biswas
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | - Daniel Lane
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
| | | | - Andre Simpson
- University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario M1C1A4, Canada
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