Assigning regioisomeric or diastereoisomeric relations of problematic trisubstituted double-bonds through heteronuclear 2D selective J-resolved NMR spectroscopy

Hoffmann, Marie; Miaskiewicz, Solène; Weibel, Jean‐Marc; Pale, Patrick; Blanc, Aurélien

doi:10.1039/c5ra03228h

Cited by 10 publications

(4 citation statements)

References 64 publications

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“…The cis -configured compound cis - 1b readily reacted with pinacol phenylboronate 2c under the conditions set up above, providing enyne 4 as the sole product in high yield (Table 2, entry 1). NMR analysis revealed the Z- stereochemistry of this enyne [31]. In contrast, the trans- isomer trans - 1b afforded a mixture of the 2 possible isomers, although in similar overall yield (Table 2, entry 2 vs 1).…”

Section: Resultsmentioning

confidence: 99%

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

Fuentespina¹,

Cruz²,

Durin³

et al. 2019

Beilstein J. Org. Chem.

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1,3-Enynes are important building blocks in organic synthesis and also constitute the key motif in various bioactive natural products and functional materials. However, synthetic approaches to stereodefined substituted 1,3-enynes remain a challenge, as they are limited to Wittig and cross-coupling reactions. Herein, stereodefined 1,3-enynes, including tetrasubstituted ones, were straightforwardly synthesized from cis or trans-alkynylated oxiranes in good to excellent yields by a one-pot cascade process. The procedure relies on oxirane deprotonation, borylation and a stereospecific rearrangement of the so-formed alkynyloxiranyl borates. This stereospecific process overall transfers the cis or trans-stereochemistry of the starting alkynyloxiranes to the resulting 1,3-enynes.

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Section: Resultsmentioning

confidence: 99%

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

Fuentespina¹,

Cruz²,

Durin³

et al. 2019

Beilstein J. Org. Chem.

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“…[8a] , 该反应的可能机理也应该为一典型的陆氏[3＋2]环化反应(Scheme 2). 首先实验中所用原料 1a～1r [9] , 1v [10] , 2a～2c [11] 是根据文献自制; 四氢呋喃(THF)、乙腈、二氯甲烷、三氯甲烷、甲苯按标准程序处理, 蒸馏备用, 其它试剂均为国产分析纯级试剂.…”

Section: 下以联烯丁酸酯及橙酮类化合物作为原料借助陆氏unclassified

“…133～135 ℃ (Lit. [10] 178 ℃); 1 7, 165.3, 148.1, 136.8, 131.8, 130.9, 130.3, 128.4, 124.6, 123.3, 122.7, 122.6, 112. 8, 170.8, 162.2, 152.1, 137.6, 135.1, 134.7, 129.0, 127.9, 127.4, 123.8, 121.9, 121.5, 112.5, 96.8, 60.7, 53.9, 38.2, 13.6 (d,J＝8.4 Hz,1H), 4.57 (s, 1H), 4.12～ 3.99 (m, 2H), 3.18～3.14 (m, 1H), 2.94～2.90 (m, 1H), 1.05 (t, J＝6.6 Hz, 3H); 13 C NMR (100 MHz, CDCl 3 ) δ: 202. 5,171.2,163.7,140.4,138.2,136.9,135.0,128.5,127.6,127.0,124.1,121.8,120.6,112.8,95.4,60.3,59.4,41.9,13.9;HRMS (ESI) 201.6, 170.7, 162.8, 162.1, 161.2, 151.9, 137.8, 134.8, 130.9, 130.9 130.6, 130.5, 123.8, 121.8, 121.6, 114.9, 114.7, 112.5, 96.6, 60.8, 53.2, 38.5, 13.6 1, 163.5, 162.7, 161.1, 140.6, 138.3, 136.7, 130.8, 130.8, 130.1, 130.1, 124.1, 122.0, 120.6, 114.6, 114.4, 112.8, 94.9, 60.4, 58.8, 41.8, 13.9 5,170.7,162.0,151.8,137.9,134.8,133.8,133.2,130.3,128.1,123.8,121.8,121.7,112.6,96.5,60.8,53.1,38.4,13.5;…”

Section: '-(叔丁基)-7-甲基-3-氧代-3h-螺[苯并呋喃 -22'-环戊烷]-1'-羧酸乙酯(4r-γ)的制备mentioning

confidence: 99%

Triphenylphosphine Catalyzed Lu's[3+2] Annulation of Aurones and Alkenoates: Constructing of Spiro[1-benzofuran-3-one-2,5'-cyclopentene] Polycyclic Compounds

苏瀛鹏¹,

冯亚威²,

曹林丹³

et al. 2019

Chin. J. Org. Chem.

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The PPh 3 catalyzed Lu's [3＋2] annulation of aurones with alkenoates has been developed to form spiro-[1-benzofuran-3-one-2,5'-cyclopentene] polycyclic moiety. The usefulness of this strategy has been demonstrated by the use of a wide variety of substrates to give desired polycyclic compounds in high yield under mild and simple reaction condition. This methodology research offered a fine entry for synthesis of natural product applanatumin A and its analogues.

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“…The dependence of the spectral signature on the mass distribution distinguishes MRR spectroscopy from mass spectrometry (MS). However, it also offers complementary analysis capabilities to nuclear magnetic resonance (NMR) spectroscopy, where the nuclei‐specific nature of the spectrum can make it difficult to analyze isomers with the same functional groups, such as regioisomers and diastereomers, 3 , 4 , 5 leading to a great deal of interest in correcting misassigned NMR structures. 6 , 7 While the rotational spectrum cannot directly differentiate enantiomers since they have the same moments‐of‐inertia, new techniques have been developed for this challenging chemical analysis.…”

Section: Introductionmentioning

confidence: 99%

Analysis of isomeric mixtures by molecular rotational resonance spectroscopy

Neill

Evangelisti

Pate

2023

Analytical Science Advances

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Recent developments in molecular rotational resonance (MRR) spectroscopy that have enabled its use as an analytical technique for the precise determination of molecular structure are reviewed. In particular, its use in the differentiation of isomeric compounds—including regioisomers, stereoisomers and isotopic variants—is discussed. When a mixture of isomers, such as resulting from a chemical reaction, is analyzed, it is highly desired to be able to unambiguously identify the structures of each of the components present, as well as quantify them, without requiring complex sample preparation or reference standards. MRR offers unique capabilities for addressing this analytical challenge, owing to two factors: its high sensitivity to a molecule's structure and its high spectral resolution, allowing mixtures to be resolved without separation of components. This review introduces core theoretical principles, an introduction to MRR instrumentation and the methods by which spectra can be interpreted with the aid of computational chemistry to correlate the observed patterns to molecular structures. Recent articles are discussed in which this technique was applied to help chemists complete challenging isomer analyses. Developments in the use of MRR for chiral analysis and in the measurement of isotopically labeled compounds are also highlighted.

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Assigning regioisomeric or diastereoisomeric relations of problematic trisubstituted double-bonds through heteronuclear 2D selective J-resolved NMR spectroscopy

Abstract: Although one of the first 2D NMR methods, but so far neglected, selective J-resolved NMR spectroscopy offers a unique opportunity to help organic chemists in structure elucidation, avoiding natural and non-natural product misassignments.

Cited by 10 publications

References 64 publications

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

Triphenylphosphine Catalyzed Lu's[3+2] Annulation of Aurones and Alkenoates: Constructing of Spiro[1-benzofuran-3-one-2,5'-cyclopentene] Polycyclic Compounds

Analysis of isomeric mixtures by molecular rotational resonance spectroscopy

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