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Wednesday 30 January 2019

Nickel-catalyzed regioselective C–H oxygenation: new routes for versatile C–O bond formation

Graphical abstract: Nickel-catalyzed regioselective C–H oxygenation: new routes for versatile C–O bond formation

Nickel-catalyzed regioselective C–H oxygenation: new routes for versatile C–O bond formation

Org. Chem. Front., 2019, Advance Article
DOI: 10.1039/C8QO01274A, Research Article
Ze-lin Li, Kang-kang Sun, Chun Cai
Nickel-catalyzed regioselective C–H oxygenation reactions of chelating arenes using iodobenzene diacetate, alcohols, and benzoic acids respectively as attacking reagents have been developed for the first time.
To cite this article before page numbers are assigned, use the DOI form of citation above.

Abstract

Nickel-catalyzed regioselective C–H oxygenation reactions of chelating arenes using iodobenzene diacetate, alcohols, and benzoic acids respectively as attacking reagents have been developed for the first time. Simplicity of operation, broad range of functional group tolerance, use of cheap transition metal nickel, and avoiding extraneous directing groups are the key features, thus providing an important complement to C–H oxygenation reactions and expanding the field of nickel-catalyzed C–H functionalizations. Explorations of mechanistic details are also described.

Nickel-catalyzed regioselective C–H oxygenation: new routes for versatile C–O bond formation

2-(pyridin-2-yl)phenyl acetate (2a)
str1
Formula: C13H11NO2 Mass: 213
To a mixture of 2-phenylpyridine (77.5 mg, 0.5 mmol) 1a, Ni(acac)2 (25.7 mg, 0.1 mmol, 20 mol %), ligand MePh2P (20.0 mg, 0.1 mmol, 20 mol %), and PhI(OAc)2 (483.2 mg, 0.75 mmol, 1.5 equiv) in a reaction tube was added solvent (CH3CN=2.0 mL). The reaction mixture was stirred at 115 °C for 24 h in air. Following the general procedure, 2a was purified by column chromatography on silica gel (petroleum ether: ethyl acetate = 5:1) as a white solid (80.9 mg, 76%).
1H NMR (500 MHz, Chloroform-d) δ 8.8 – 8.7 (m, 1H), 7.8 – 7.7 (m, 2H), 7.6 (dd, J = 7.9, 1.1 Hz, 1H), 7.5 (td, J = 7.7, 1.7 Hz, 1H), 7.4 (td, J = 7.5, 1.2 Hz, 1H), 7.3 – 7.3 (m, 1H), 7.2 (dd, J = 8.0, 1.2 Hz, 1H), 2.2 (s, 3H).
13C NMR (126 MHz, Chloroform-d) δ 168.4, 154.9, 148.6, 147.1, 135.3, 132.2, 129.8, 128.7, 125.4, 122.6, 122.3, 121.2, 20.0. GC-MS (EI) m/z: 213
str2 str3
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Tuesday 29 January 2019

Large scale synthesis of chiral (3Z,5Z)-2,7-dihydro-1H-azepine-derived Hamari ligand for general asymmetric synthesis of tailor-made amino acids.

str3 str4
(R)-2,2′-bis(bromomethyl)-1,1′-binaphthalene ((R)-17) was prepared in the identical manner and had identical analytical properties to those given here.
1H NMR (400 MHz, CDCl3): δ 4.25 (4H, s, 2 × CH2), 7.07 (2H, dd, J = 8.4, 0.8 Hz, ArH), 7.27 (2H, ddd, J = 8.4, 6.8, 1.2 Hz, ArH), 7.48 (2H, ddd, J = 8.2, 6.8, 1.2 Hz, ArH), 7.74 (2H, d, J = 8.6 Hz, ArH), 7.92 (2H, d, J = 8.2 Hz, ArH), 8.02 (2H, d, J = 8.6 Hz, ArH).
13C NMR (100.6 MHz, CDCl3): δ 32.6 (CH2), 126.80 (ArCH), 126.82 (ArCH), 126.84 (ArCH), 127.7 (ArCH), 128.0 (ArCH), 129.4 (ArCH), 132.5 (quaternary ArC), 133.3 (quaternary ArC), 134.1 (quaternary ArC), 134.2 (quaternary ArC).
[α]20D = +173.8° (c = 1.0, CHCl3).


Abstract Image
An advanced process for large scale (500 g) preparation of a (3Z,5Z)-2,7-dihydro-1H-azepine-derived chiral tridentate ligand (Hamari ligand), widely used for asymmetric synthesis of tailor-made α-amino acids via the corresponding glycine Schiff base Ni(II) complex, is disclosed. The process includes amidation, bis-alkylation, and precipitation/purification of the target compound by TFA as a counterion.
Large Scale Synthesis of Chiral (3Z,5Z)-2,7-Dihydro-1H-azepine-Derived Hamari Ligand for General Asymmetric Synthesis of Tailor-Made Amino Acids
 Hamari Chemicals Ltd., 1-4-29 Kunijima, Higashi-Yodogawa-ku, Osaka 533-0024, Japan
 Hamari Chemicals USA, San Diego Research Center11494 Sorrento Valley Road, San Diego, California 92121, United States
§ Department of Organic Chemistry I, Faculty of ChemistryUniversity of the Basque Country UPV/EHUPaseo Manuel Lardizábal 3, 20018 San Sebastián, Spain
 IKERBASQUE, Basque Foundation for ScienceMaría Díaz de Haro 3, Plaza Bizkaia, 48013 Bilbao, Spain
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.8b00406
Publication Date (Web): January 18, 2019
Copyright © 2019 American Chemical Society
This article is part of the Japanese Society for Process Chemistry special issue.
 


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Photo-organocatalytic synthesis of acetals from aldehydes

Graphical abstract: Photo-organocatalytic synthesis of acetals from aldehydes

Abstract

A mild and green photo-organocatalytic protocol for the highly efficient acetalization of aldehydes has been developed. Utilizing thioxanthenone as the photocatalyst and inexpensive household lamps as the light source, a variety of aromatic and aliphatic aldehydes have been converted into acyclic and cyclic acetals in high yields. The reaction mechanism was extensively studied

Photo-organocatalytic synthesis of acetals from aldehydes

 
 Author affiliations
https://pubs.rsc.org/en/Content/ArticleLanding/2019/GC/C8GC03605E?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract
STR1
(3,3-Dimethoxypropyl)benzene (2a)6
Colorless oil; 95% yield; 1H NMR (200 MHz, CDCl3) δ: 7.33-7.18 (5H, m, ArH), 4.37 (1H, t, J = 5.8 Hz, OCH), 3.33 (6H, s, 2 x OCH3), 2.68 (2H, t, J = 7.6 Hz, CH2), 1.98- 1.87 (2H, m, CH2); 13C NMR (50 MHz, CDCl3) δ: 141.8, 128.4, 125.9, 103.7, 52.8, 34.0, 30.8; MS (ESI) m/z 181 [M+H]+ .
6. Q. Zhou, T. Jia. X.-X. Li, L. Zhou, C.-J. Li, Y. S. Feng, Synth. Commun., 2018, 48, 1068.
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Eco-friendly decarboxylative cyclization in water: practical access to the anti-malarial 4-quinolones

Graphical abstract: Eco-friendly decarboxylative cyclization in water: practical access to the anti-malarial 4-quinolones

Abstract

An environmentally benign decarboxylative cyclization in water has been developed to synthesize 4-quinolones from readily available isatoic anhydrides and 1,3-dicarbonyl compounds. Isatins are also compatible for the reaction to generate 4-quinolones in the presence of TBHP in DMSO. This protocol provides excellent yields under mild conditions for a broad scope of 4-quinolones, and has good functional group tolerance. Only un-harmful carbon dioxide and water are released in this procedure. Moreover, the newly synthesized products have also been selected for anti-malarial examination against the chloroquine drug-sensitive Plasmodium falciparum 3D7 strain. 3u is found to display excellent anti-malarial activity with an IC50 value of 33 nM.

Eco-friendly decarboxylative cyclization in water: practical access to the anti-malarial 4-quinolones

 
 Author affiliations
https://pubs.rsc.org/en/Content/ArticleLanding/2019/GC/C8GC03570A?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract
ethyl 2-(4-(benzyloxy)phenyl)-4-oxo-1,4-dihydroquinoline-3-carboxylate (3u) White solid, m.p. 288-289 oC;
1H NMR (600 MHz, DMSO-d6) δ 12.14 (s, 1H), 8.13 (d, J = 8.0 Hz, 1H), 7.72 (ddd, J = 8.4, 7.1, 1.5 Hz, 1H), 7.64 (d, J = 8.3 Hz, 1H), 7.52 (td, J = 8.5, 1.7 Hz, 1H), 7.43 – 7.35 (m, 4H), 7.29 – 7.21 (m, 4H), 7.10 (td, J = 7.5, 0.5 Hz, 1H), 5.17 (s, 2H), 3.91 (q, J = 7.1 Hz, 2H), 2.00 (s, 1H), 0.83 (t, J = 7.1 Hz, 3H) ppm;
13C NMR (150 MHz, DMSO-d6) δ 174.1, 166.2, 156.2, 148.0, 139.8, 137.2, 132.8, 132.0, 130.5, 129.4, 128.7, 128.2, 127.6, 125.5, 125.2, 124.3, 123.6, 120.9, 118.9, 116.4, 115.8, 113.5, 70.2, 60.2, 14.0 ppm;
HRMS (ESI) calcd for [C25H21NO4+H]+ 400.1471, found 400.1463.
STR1 STR2

A solvent-free catalytic protocol for the Achmatowicz rearrangement

Graphical abstract: A solvent-free catalytic protocol for the Achmatowicz rearrangement

Abstract

Reported here is the development of an environmentally friendly catalytic (KBr/oxone) and solvent-free protocol for the Achmatowicz rearrangement (AchR). Different from all previous methods is that the use of chromatographic alumina (Al2O3) allows AchR to proceed smoothly in the absence of any organic solvent and therefore considerably facilitates the subsequent workup and purification with minimal environmental impacts. Importantly, this protocol allows for scaling up (from milligram to gram), recycling of the Al2O3, and integrating with other reactions in a one-pot sequential manner.

A solvent-free catalytic protocol for the

Achmatowicz rearrangement

 
 Author affiliations
1n: colorless oil, 0.33 g, 73% yield for 2 steps.
1H-NMR (400 MHz, DMSO) δ: 7.59–7.58 (m, 1H), 7.45 (s, 2H), 6.40 (dd, J = 3.2, 1.8 Hz, 1H), 6.29 (d, J = 3.2 Hz, 1H), 5.49 (s, 1H), 4.74–4.60 (m, 1H), 4.18–4.07 (m, 2H), 2.09–2.04 (m, 2H).
13C-NMR (100 MHz, DMSO) δ: 157.6, 142.4, 110.7, 106.1, 66.5, 62.8, 35.2. IR (KBr) 3282.9, 2928.7, 1627.4, 1562.5, 1353.8, 1174.6, 1074.0, 999.7, 918.4, 742.8 cm-1 ;
HRMS (CI+ ) (m/z) calcd. for C7H11NO5S [M]+ 221.0352; found 221.0354.
STR1 STR2 str3



2n (EtOAc/hexane = 3:1):colorless oil (dr 7:3), 46 mg, 97%.
1H-NMR (400 MHz, DMSO) δ: 7.48–7.47 (m, 2H), 7.34–7.02 (m, 2H), 6.12–6.03 (m, 1H), 5.61–5.48 (m, 1H), 4.60 (dd, J = 8.3, 4.1 Hz, 0.7H), 4.28 (ddd, J = 8.8, 4.0, 1.3 Hz, 0.3H), 4.20–4.11 (m, 2H), 2.27–2.20 (m, 1H), 1.97–1.86 (m, 1H).
13C-NMR (100 MHz, DMSO) δ: 196.7, 196.5, 151.9, 148.3, 127.7, 126.0, 90.9, 87.2, 74.6, 70.1, 65.8, 65.8, 30.3, 29.6. IR (KBr) 3370.4, 2987.0, 1689.5, 1364.3, 1268.0, 1178.4, 1023.3, 928.3, 755.1 cm-1 ;
HRMS (CI+ ) (m/z) calcd. for C7H11NO6S [M]+ 237.0302; found 237.0315.
STR1 STR2
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