Dataset Information

Parahydrogen-Induced Polarization of 1-13C-Acetates and 1-13C-Pyruvates Using Sidearm Hydrogenation of Vinyl, Allyl, and Propargyl Esters.

ABSTRACT: 13C-hyperpolarized carboxylates, such as pyruvate and acetate, are emerging molecular contrast agents for MRI visualization of various diseases, including cancer. Here we present a systematic study of 1H and 13C parahydrogen-induced polarization of acetate and pyruvate esters with ethyl, propyl and allyl alcoholic moieties. It was found that allyl pyruvate is the most efficiently hyperpolarized compound from those under study, yielding 21% and 5.4% polarization of 1H and 13C nuclei, respectively, in CD3OD solutions. Allyl pyruvate and ethyl acetate were also hyperpolarized in aqueous phase using homogeneous hydrogenation with parahydrogen over water-soluble rhodium catalyst. 13C polarization of 0.82% and 2.1% was obtained for allyl pyruvate and ethyl acetate, respectively. 13C-hyperpolarized methanolic and aqueous solutions of allyl pyruvate and ethyl acetate were employed for in vitro MRI visualization, demonstrating the prospects for translation of the presented approach to biomedical in vivo studies.

SUBMITTER: Salnikov OG

PROVIDER: S-EPMC6664436 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

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Publications

Parahydrogen-Induced Polarization of 1-13C-Acetates and 1-13C-Pyruvates Using Sidearm Hydrogenation of Vinyl, Allyl, and Propargyl Esters.

Salnikov Oleg G OG Chukanov Nikita V NV Shchepin Roman V RV Manzanera Esteve Isaac V IV Kovtunov Kirill V KV Koptyug Igor V IV Chekmenev Eduard Y EY

The journal of physical chemistry. C, Nanomaterials and interfaces 20190419 20

13C-hyperpolarized carboxylates, such as pyruvate and acetate, are emerging molecular contrast agents for MRI visualization of various diseases, including cancer. Here we present a systematic study of 1H and 13C parahydrogen-induced polarization of acetate and pyruvate esters with ethyl, propyl and allyl alcoholic moieties. It was found that allyl pyruvate is the most efficiently hyperpolarized compound from those under study, yielding 21% and 5.4% polarization o ...[more]

PMID: 31363383

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Project description:Conjugate (or 1,4-) additions of carbanionic species to ?,?-unsaturated carbonyl compounds are vital to research in organic and medicinal chemistry, and there are several chiral catalysts that facilitate the catalytic enantioselective additions of nucleophiles to enoates. Nonetheless, catalytic enantioselective 1,6-conjugate additions are uncommon, and ones that incorporate readily functionalizable moieties, such as propargyl or allyl groups, into acyclic ?,?,?,?-doubly unsaturated acceptors are unknown. Chemical transformations that could generate a new bond at the C6 position of a dienoate are particularly desirable because the resulting products could then be subjected to further modifications. However, such reactions, especially when dienoates contain two equally substituted olefins, are scarce and are confined to reactions promoted by a phosphine-copper catalyst (with an alkyl Grignard reagent, dialkylzinc or trialkylaluminium compounds), a diene-iridium catalyst (with arylboroxines), or a bisphosphine-cobalt catalyst (with monosilyl-acetylenes). 1,6-Conjugate additions are otherwise limited to substrates where there is full substitution at the C4 position. It is unclear why certain catalysts favour bond formation at C6, and-although there are a small number of catalytic enantioselective conjugate allyl additions-related 1,6-additions and processes involving a propargyl unit are non-existent. Here we show that an easily accessible organocopper catalyst can promote 1,6-conjugate additions of propargyl and 2-boryl-substituted allyl groups to acyclic dienoates with high selectivity. A commercially available allenyl-boron compound or a monosubstituted allene may be used. Products can be obtained in up to 83 per cent yield, >98:2 diastereomeric ratio (for allyl additions) and 99:1 enantiomeric ratio. We elucidate the mechanistic details, including the origins of high site selectivity (1,6- versus 1,4-) and enantioselectivity as a function of the catalyst structure and reaction type, by means of density functional theory calculations. The utility of the approach is highlighted by an application towards enantioselective synthesis of the anti-HIV agent (-)-equisetin.

Dataset Information

Parahydrogen-Induced Polarization of 1-13C-Acetates and 1-13C-Pyruvates Using Sidearm Hydrogenation of Vinyl, Allyl, and Propargyl Esters.

Publications

Parahydrogen-Induced Polarization of 1-<sup>13</sup>C-Acetates and 1-<sup>13</sup>C-Pyruvates Using Sidearm Hydrogenation of Vinyl, Allyl, and Propargyl Esters.

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