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Keywords = 2-fluoronitrobenzene

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16 pages, 4421 KiB  
Article
Synthesis and Catalytic Activity of 1,2-Benzenediamine-Derived Organocatalysts Based on (1R,2R)-Cyclohexane-1,2-Diamine
by Luka Ciber, Klara Klemenčič, Ana Golob, Helena Brodnik, Franc Požgan, Jurij Svete, Bogdan Štefane and Uroš Grošelj
Catalysts 2024, 14(4), 274; https://doi.org/10.3390/catal14040274 - 18 Apr 2024
Viewed by 2356
Abstract
A four-step synthesis process of bifunctional, noncovalent organocatalysts based on the chiral (1R,2R)-cyclohexane-1,2-diamine scaffold containing a 1,2-benzenediamine H-bond donor was developed. Nucleophilic aromatic substitution of the 2-fluoronitrobenzene derivative with the commercial (1R,2R)-cyclohexane-1,2-diamine was followed by [...] Read more.
A four-step synthesis process of bifunctional, noncovalent organocatalysts based on the chiral (1R,2R)-cyclohexane-1,2-diamine scaffold containing a 1,2-benzenediamine H-bond donor was developed. Nucleophilic aromatic substitution of the 2-fluoronitrobenzene derivative with the commercial (1R,2R)-cyclohexane-1,2-diamine was followed by selective alkylation of the primary amino group, reduction of the aromatic nitro group and final derivatization of the primary aromatic amino group, i.e., acylation, sulfonation, reductive alkylation and arylation, leading to the four subtypes of organocatalysts. All new compounds were fully characterized. The prepared organocatalysts (32 examples) were tested in the Michael addition of acetylacetone to trans-β-nitrostyrene, yielding the addition product with incomplete conversions (up to 93%) and enantioselectivities of up to 41% ee. Full article
(This article belongs to the Special Issue Organocatalysis in the Chemical Transformations, 2nd Edition)
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8 pages, 1779 KiB  
Communication
Structural Characterization of 4-(4-Nitrophenyl)thiomorpholine, a Precursor in Medicinal Chemistry
by Paul R. Palme, Richard Goddard, Peter Imming and Rüdiger W. Seidel
Molbank 2024, 2024(1), M1795; https://doi.org/10.3390/M1795 - 20 Mar 2024
Viewed by 3070
Abstract
4-(4-nitrophenyl)thiomorpholine, the title compound, has been used as a precursor for the corresponding 4-thiomorpholinoaniline, which is a useful building block in medicinal chemistry. The crystal and molecular structures of the title compound, however, have not been described thus far. We synthesized the title [...] Read more.
4-(4-nitrophenyl)thiomorpholine, the title compound, has been used as a precursor for the corresponding 4-thiomorpholinoaniline, which is a useful building block in medicinal chemistry. The crystal and molecular structures of the title compound, however, have not been described thus far. We synthesized the title compound by means of a nucleophilic aromatic substitution reaction of 4-fluoronitrobenzene and thiomorpholine and structurally characterized it by X-ray crystallography, DFT calculations, and Hirshfeld surface analysis. In the crystal, the molecule exhibits an approximately CS-symmetric structure, with the nitrogen-bound 4-nitrophenyl group in a quasi axial position on the six-membered thiomorpholine ring in a low-energy chair conformation. The solid-state structure of the title compound is markedly different from that of its morpholine analogue. This can be ascribed to the formation of centrosymmetric dimers through intermolecular C–H···O weak hydrogen bonds involving the methylene groups adjacent to the sulfur atom and face-to-face aromatic stacking. Full article
(This article belongs to the Section Structure Determination)
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6 pages, 1233 KiB  
Communication
Synthesis of N1-(3,5-Bis(trifluoromethyl)benzyl)benzene-1,2-diamine and N,N-Bis(2-nitrophenyl)-3,5-bis(trifluoromethyl)aniline
by Luka Ciber, Helena Brodnik, Franc Požgan, Jurij Svete, Bogdan Štefane and Uroš Grošelj
Molbank 2023, 2023(3), M1718; https://doi.org/10.3390/M1718 - 4 Sep 2023
Viewed by 2380
Abstract
A monosubstituted benzene-1,2-diamine building block, N1-(3,5-bis(trifluoromethyl)benzyl)benzene-1,2-diamine, was prepared in two steps from commercially available 3,5-bis(trifluoromethyl)benzylamine and 1-fluoro-2-nitrobenzene, while the use of 3,5-bis(trifluoromethyl)aniline as the starting amine gave a triarylamine, N,N-bis(2-nitrophenyl)-3,5-bis(trifluoromethyl)aniline. The structures of the newly synthesized compounds were fully characterized. Full article
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5 pages, 544 KiB  
Short Note
1-{(1S,2S,4R)-7,7-Dimethyl-1-[(pyrrolidin-1-yl)methyl]bicyclo [2.2.1]heptan-2-yl}-1H-benzo[d]imidazole
by Luka Ciber, Franc Požgan, Jurij Svete, Bogdan Štefane and Uroš Grošelj
Molbank 2023, 2023(1), M1538; https://doi.org/10.3390/M1538 - 6 Jan 2023
Cited by 1 | Viewed by 2872
Abstract
A three-step synthesis of 1-{(1S,2S,4R)-7,7-dimethyl-1-[(pyrrolidin-1-yl)methyl]bicyclo[2.2.1]heptan-2-yl}-1H-benzo[d]imidazole, prepared from camphor derived diamine, is disclosed. The absolute configuration at the chiral center bearing benzo[d]imidazole moiety was confirmed by NOESY. The structure of a newly [...] Read more.
A three-step synthesis of 1-{(1S,2S,4R)-7,7-dimethyl-1-[(pyrrolidin-1-yl)methyl]bicyclo[2.2.1]heptan-2-yl}-1H-benzo[d]imidazole, prepared from camphor derived diamine, is disclosed. The absolute configuration at the chiral center bearing benzo[d]imidazole moiety was confirmed by NOESY. The structure of a newly synthesized compound was confirmed by 1H- and 13C-NMR, 2D NMR, IR spectroscopy, and high resolution mass-spectrometry. Full article
(This article belongs to the Topic Organocatalysis and Transition-Metal Catalysis: Key Trends in Synthetic Chemistry and Challenges)
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25 pages, 2112 KiB  
Article
Synthesis and Catalytic Activity of Organocatalysts Based on Enaminone and Benzenediamine Hydrogen Bond Donors
by Luka Ciber, Franc Požgan, Helena Brodnik, Bogdan Štefane, Jurij Svete and Uroš Grošelj
Catalysts 2022, 12(10), 1132; https://doi.org/10.3390/catal12101132 - 28 Sep 2022
Cited by 6 | Viewed by 2772
Abstract
A total of 24 novel organocatalysts based on (S)-quininamine as a chiral tertiary amine and on enaminone or 1,2-benzenediamine as hydrogen bond donors were synthesized. The enaminone-type catalysts were prepared by the transamination of N,N-dimethyl enaminones with ( [...] Read more.
A total of 24 novel organocatalysts based on (S)-quininamine as a chiral tertiary amine and on enaminone or 1,2-benzenediamine as hydrogen bond donors were synthesized. The enaminone-type catalysts were prepared by the transamination of N,N-dimethyl enaminones with (S)-quininamine (9 examples) and the 1,2-benzenediamine-type catalysts were prepared in 3 steps from (S)-quininamine and ortho-fluoronitrobenzene derivatives (15 examples). Their organocatalytic activity was evaluated in the Michael addition of acetylacetone to trans-β-nitrostyrene. Enantioselectivities of up to 72% ee were observed. Full article
(This article belongs to the Special Issue State-of-the-Art in Asymmetric Organocatalysis)
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14 pages, 21349 KiB  
Article
Low-Dissipation Thermosets Derived from Oligo(2,6-Dimethyl Phenylene Oxide)-Containing Benzoxazines
by Chien-Han Chen, Kuan-Wei Lee, Ching-Hsuan Lin and Tzong-Yuan Juang
Polymers 2018, 10(4), 411; https://doi.org/10.3390/polym10040411 - 7 Apr 2018
Cited by 19 | Viewed by 7750
Abstract
Poly(2,6-dimethyl phenyl oxide) (PPO) is known for its low dissipation factor. To achieve insulating materials with low dissipation factors for high-frequency communication applications, a telechelic oligomer-type benzoxazine (P-APPO) and a main-chain type benzoxazine polymer (BPA-APPO) were prepared from an amine end-capped oligo (2,6-dimethyl [...] Read more.
Poly(2,6-dimethyl phenyl oxide) (PPO) is known for its low dissipation factor. To achieve insulating materials with low dissipation factors for high-frequency communication applications, a telechelic oligomer-type benzoxazine (P-APPO) and a main-chain type benzoxazine polymer (BPA-APPO) were prepared from an amine end-capped oligo (2,6-dimethyl phenylene oxide) (APPO). The APPO was prepared from a nucleophilic substitution of a phenol-end capped oligo (2,6-dimethyl phenylene oxide) (a commercial product, SA 90) with fluoronitrobenzene, and followed by catalytic hydrogenation. After self-curing or curing with a dicyclopentadiene-phenol epoxy (HP 7200), thermosets with high-Tg and low-dissipation factor can be achieved. Furthermore, the resulting epoxy thermosets show better thermal and dielectric properties than those of epoxy thermoset cured from its precursor SA90, demonstrating it is a successful modification in simultaneously enhancing the thermal and dielectric properties. Full article
(This article belongs to the Special Issue New Developments in Ring-Opening Polymerization)
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2 pages, 106 KiB  
Short Note
New 1-(4-nitrophenyl)-5,5’-diisopropyl-3,3’-bipyrazole
by Ibrahim Bouabdallah, Ismail Zidane, Rachid Touzani, Abdelkrim Ramdani, Abraham F. Jalbout and B. Trzaskowski
Molbank 2006, 2006(5), M490; https://doi.org/10.3390/M490 - 1 Sep 2006
Viewed by 4593
Abstract
To a solution of 5,5’-diisopropyl-3,3’-bipyrazole 1 [1] (109 mg, 0.5 mmol) in DMSO (2 ml) was added solid potassium tert-butoxide (61 mg, 0.5 mmol) followed by addition of 4-fluoronitrobenzene (70.5 mg, 0.5 mmol) in DMSO (1 ml) through a syringe, according to literature [...] Read more.
To a solution of 5,5’-diisopropyl-3,3’-bipyrazole 1 [1] (109 mg, 0.5 mmol) in DMSO (2 ml) was added solid potassium tert-butoxide (61 mg, 0.5 mmol) followed by addition of 4-fluoronitrobenzene (70.5 mg, 0.5 mmol) in DMSO (1 ml) through a syringe, according to literature procedure [2].[...] Full article
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