- Phthalide synthesis through dehydrogenated lactonization of the C(sp3)-H bond by photoredox catalysis
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A practical and efficient method is established for the direct oxidative lactonization of the C(sp3)-H bonds relying on visible-light-induced photoredox catalysis. This protocol expediently allows the delivery of diverse phthalides using oxygen as the sole terminal oxidant under metal-free conditions at room temperature. Notably, the choice of an appropriate hydrogen atom transfer (HAT) cocatalyst is revealed to be critical for the success of this process.
- Cai, Shunyou,Cai, Zhixiong,Chen, Shanyi,Huang, Mingqiang,Lai, Qihong,Lin, Yulin,Liu, Chao,Liu, Hui
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supporting information
p. 8212 - 8216
(2021/10/29)
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- Palladium-Catalyzed Acylation Reactions: A One-Pot Diversified Synthesis of Phthalazines, Phthalazinones and Benzoxazinones
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A sequential one-pot strategy for the diversified synthesis of phthalazines, phthalazinones and benzoxazinones was presented. This strategy proceeds through [Pd]-catalyzed acylation and nucleophilic cyclocondensation with dinucleophilic reagents. This process was based on direct coupling with simple bench-top aldehydes without the assistance of directing group and without activating the carbonyl group. The process is highly advantageous because it employs simple nitrogen-based nucleophiles, and non-toxic and readily accessible aldehydes as the carbonyl source. Most importantly, the strategy was applied to the one-pot synthesis of PDE-4 inhibitor.
- Suchand, Basuli,Satyanarayana, Gedu
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p. 2233 - 2246
(2018/06/04)
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- Ruthenium-Catalyzed Enantioselective Hydrogenation/Lactonization of 2-Acylarylcarboxylates: Direct Access to Chiral 3-Substituted Phthalides
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Highly enantioselective tandem hydrogenation/lactonization of various 2-acylarylcarboxylates including 2-aroylarylcarboxylates were realized by using [RuCl(benzene)(S)-SunPhos]Cl as the catalyst under mild reaction conditions. Excellent enantioselectivities (up to 99.6 % ee) and activities (S/C=1000) were obtained. This convenient and practical method enables a direct access to a series of highly optically pure 3-substituted phthalides that are very important molecules as valuable pharmacological compounds and diversified synthons for medicinal chemistry. Moreover, a gram-scale reaction was performed to further demonstrate the practicality of this approach.
- Lu, Bin,Zhao, Mengmeng,Ding, Guangni,Xie, Xiaomin,Jiang, Lili,Ratovelomanana-Vidal, Virginie,Zhang, Zhaoguo
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p. 3989 - 3996
(2017/09/13)
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- Stereoselective synthesis of 3-substituted phtalides via asymmetric transfer hydrogenation using well-defined ruthenium catalysts under neutral conditions
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The asymmetric transfer hydrogenation of methyl 2-acylbenzoates and 2-propyl 3-acetylpyridine-2-carboxylate in 2-propanol, in the absence of base, with presynthesized Ru-{β-amino alcohol} or Ru-{TsDPEN} true catalysts provides 3-alkylphtalides in high yields and 92-97% ee. The procedure is, however, not as efficient for the preparation of optically active 3-phenylphtalide.
- Everaere, Kathelyne,Scheffler, Jean-Luc,Mortreux, André,Carpentier, Jean-Fran?ois
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p. 1899 - 1901
(2007/10/03)
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- Microbial asymmetric syntheses of 3-alkylphthalide derivatives
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Phthalide derivatives, almost all of which have an S-configuration, have a wide range of activity and exist in Angerica sinensis Diels and Sligusticum wallichiii Franch. For the first time, optically active (S)-3-methylphthalide derivatives were synthesized using two methods, asymmetric microbial reduction and microbial hydroxylation. For the first method, methyl 2-acetylbenzoate was synthesized as a substrate, which was reduced asymmetrically by Geotrichum candidum IFO 34614 to obtain (S)-3-methylphtalide in 92% yield (99% enantiomeric excess, ee). For the second method, 2-ethylbenzoic acid was employed as a substrate which was hydroxylated asymmetrically at the benzylic position by either Pseudomonas putida ATCC 12633 or Aspergillus niger IFO 6661, whose fermentation was induced by o-toluic acid, to obtain (S)-3-methylphthalide in 80% yield (99% ee). (S)-3-Butylphthalide and (S)-3-octylphthalide were obtained in the same manner in 12% yield (ee = 99%) and 10% yield (ee = 99%), respectively.
- Kitayama, Takashi
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p. 3765 - 3774
(2007/10/03)
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- Deactivation of Triplet Phenyl Alkyl Ketones by Conjugatively Electron-Withdrawing Substituents
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Para-cyano, -carbomethoxy, and -acyl substituents decrease the triplet reactivity of valerophenone (γ-hydrogen abstraction), whereas comparable meta substituents increase reactivity.Spectroscopic results are presented which indicate that para-(-R) substituents lower ?,?* triplet energies so much more than n,?* energies that the lowest triplets become largely ?,?* in nature.Meta-(-R) substituents do not stabilize ?,?* triplets enough to invert triplet levels.Both substitution patterns support a largely 1,4-biradical structure for the lowest ?,?* triplet of acylbenzenes.Ortho substituents show the usual steric anomalies: ortho cyano enhances valerophenone triplet reactivity by stabilizing the n,?* triplet; ortho carbomethoxy deactivates valerophenone by stabilizing the ?,?* triplet but not the n,?.*
- Wagner, Peter J.,Siebert, Elizabeth J.
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p. 7329 - 7335
(2007/10/02)
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