- Experimental and Computational Studies of Palladium-Catalyzed Spirocyclization via a Narasaka-Heck/C(sp3or sp2)-H Activation Cascade Reaction
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The first synthesis of highly strained spirocyclobutane-pyrrolines via a palladium-catalyzed tandem Narasaka-Heck/C(sp3 or sp2)-H activation reaction is reported here. The key step in this transformation is the activation of a δ-C-H bond via an in situ generated σ-alkyl-Pd(II) species to form a five-membered spiro-palladacycle intermediate. The concerted metalation-deprotonation (CMD) process, rate-determining step, and energy barrier of the entire reaction were explored by density functional theory (DFT) calculations. Moreover, a series of control experiments was conducted to probe the rate-determining step and reversibility of the C(sp3)-H activation step.
- Wei, Wan-Xu,Li, Yuke,Wen, Ya-Ting,Li, Ming,Li, Xue-Song,Wang, Cui-Tian,Liu, Hong-Chao,Xia, Yu,Zhang, Bo-Sheng,Jiao, Rui-Qiang,Liang, Yong-Min
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supporting information
p. 7868 - 7875
(2021/05/27)
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- Iron-Catalyzed Cleavage Reaction of Keto Acids with Aliphatic Aldehydes for the Synthesis of Ketones and Ketone Esters
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The radical–radical coupling reaction is an important synthetic strategy. In this study, the iron-catalyzed radical–radical cross-coupling reaction based on the decarboxylation of keto acids and decarbonylation of aliphatic aldehydes to obtain valuable aryl ketones is reported for the first time. Remarkably, when tertiary aldehydes were used as carbonyl sources, ketone esters were selectively obtained instead of ketones. The gram-scale preparation of aryl ketone through this strategy was easily achieved by using only 3 mol % of the iron catalyst. As a proof-of-concept, the bioactive molecule flurprimidol was synthesized in two steps by using this strategy.
- Zhou, Fangyuan,Li, Lesong,Lin, Kao,Zhang, Feng,Deng, Guo-Jun,Gong, Hang
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supporting information
p. 4246 - 4250
(2020/03/11)
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- Method for preparing aryl ketone based on iron-catalyzed free radical-free radical coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation
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The invention discloses a method for preparing an aryl ketone derivative based on a free radical-free radical cross-coupling reaction such as ketonic acid decarboxylation and fatty aldehyde de-carbonylation. The method comprises the following steps: reacting aryl-substituted ketonic acid with fatty aldehyde under the catalytic action of ferric triacetylacetonate to generate an aryl ketone derivative; the gram-grade reaction can be realized by the method only by using 3mol% of an iron catalyst; and the method has the advantages of no need of consumption of a large amount of a Lewis acid catalyst or a stoichiometric organic metal reagent, mild reaction conditions, one-step reaction, few by-products, wide substrate application range and scalable reaction, and overcomes the defects of large catalyst consumption, insufficient functional group tolerance, many by-products and the like in the prior art.
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Paragraph 0071-0072
(2020/05/05)
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- O-Trifluoromethylation of Phenols: Access to Aryl Trifluoromethyl Ethers by O-Carboxydifluoromethylation and Decarboxylative Fluorination
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A new strategy for the synthesis of aryl trifluoromethyl ethers (ArOCF3) by combining O-carboxydifluoromethylation of phenols and subsequent decarboxylative fluorination is reported. This protocol allows easy construction of functionalized trifluoromethoxybenzenes and trifluoromethylthiolated arenes (ArSCF3) in moderate to good yields. Moreover, it utilizes accessible and inexpensive reagents sodium bromodifluoroacetate and SelectFluor II and, thus, is practical for O-trifluoromethylation of phenols. The potential application of this method is demonstrated with the preparation of a plant-growth regulator, Flurprimidol.
- Zhou, Min,Ni, Chuanfa,He, Zhengbiao,Hu, Jinbo
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supporting information
p. 3754 - 3757
(2016/08/16)
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- Acylation du trifluoromethoxybenzene en catalyse HF-BF3
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Friedel and Crafts acylation of trifluoromethoxy- and trifluoromethyl-thiobenzene fails to give ketones in a one step synthesis if chlorinated Lewis acids (AlCl3) are used, because of halogen exchange on the -OCF3 and -SCF3 groups.The use of a fluorinated catalyst system such as HF-BF3 avoids exchange reactions and acylation occurs smoothly under mild conditions: - Low temperature and pressure - High yields (very often >90 percent) - Very high para-regioselectivity.Related reactions such as formylation or sulfonylation can also be achieved under similar conditions.
- Desbois, Michel
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p. 885 - 890
(2007/10/02)
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- Process for the preparation of α,α-difluoroalkyl-thiophenyl ketones
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A process for the preparation of α,α-difluoroalkoxy or α,α-difluoroalkylthiophenyl ketones, in which a polyhaloalkoxybenzene or a polyhaloalkylthiobenzene is reacted with a carboxylic acid, a precursor or a derivative of this acid in the presence of boron trifluoride in such an amount that the absolute pressure of the boron trifluoride within the reaction vessel exceeds 1 bar, and in the presence of hydrofluoric acid as a solvent. The resultant products are useful as intermediates in the synthesis of compounds having phytosanitary (e.g., herbicidal) or pharmaceutical activity.
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- Chlorination of 4-methoxybenzoyl chloride
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An improved process for chlorinating 4-methoxybenzoyl chloride on the methyl group with molecular chlorine is done neat at elevated temperature in the absence of light of radical-forming intensity.
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- Method of regulating the growth of aquatic weeds with pyridine derivatives
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A method of regulating the growth of submerged and floating aquatic weeds which comprises adding a 2- or 4-substituted pyridinemethane or pyridinemethanol to a body of water containing the submerged and floating aquatic weeds to be regulated, in quantities sufficient to regulate the growth of the submerged and floating aquatic weeds therein. The disclosure also relates to novel compositions for carrying out the method.
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- Method of regulating the growth of aquatic weeds with pyridine derivatives
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A method of regulating the growth of submerged and floating aquatic weeds which comprises adding a fluoroalkoxyphenyl-substituted 3-pyridinemethanol to a body of water containing the submerged and floating aquatic weeds to be regulated, in quantities sufficient to regulate the growth of the said submerged and floating aquatic weeds. The disclosure also relates to novel compositions for carrying out the method.
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- Fluoroalkoxyphenyl-substituted nitrogen heterocycles as plant stunting agents
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There is disclosed a class of fluoroalkoxyphenyl-substituted nitrogen-containing heterocycles which are useful as herbicides, plant fungicides, and plant growth regulators. Internodal elongation of plants is inhibited by treatment with compounds of this invention.
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