- Atroposelective Arene Formation by Carbene-Catalyzed Formal [4+2] Cycloaddition
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Atroposelective arene formation is an efficient method to build axially chiral molecules with multi-substituted arenes. Reported here is an organocatalyzed atroposelective arene formation reaction by an N-heterocyclic carbene (NHC) catalyzed formal [4+2] cycloaddition of conjugated dienals and α-aryl ketones. This study expands the synthetic potential of NHC organocatalysis and provides a competitive pathway for the synthesis of axially chiral ligands, catalysts, and other functional molecules.
- Xu, Ke,Li, Wenchang,Zhu, Shaoheng,Zhu, Tingshun
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supporting information
p. 17625 - 17630
(2019/11/29)
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- Method for preparing indole and derivatives thereof
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The invention discloses a method for preparing indole and derivatives of indole. The method for preparing indole and the derivatives of indole is characterized by comprising the following two steps that (1) a catalyst, a ligand and alkali are added in a reaction tube, under the protection of nitrogen, beta-hydroxy ketone or ester is reacted with a mixed solution of o-nitro aryl halides for 3 to 8h in an oil bath pan at the temperature of 90 to 120 DEG C, and then cooled to room temperature after reaction, and extracted, washed, dried and subjected to chromatography to obtain a product of o-nitro alpha-aryl ketone or ester; (2) o-nitro alpha-aryl ketone or ester obtained in the step (1), a reducing agent system and a solvent are added to the reaction tube, and reacted for 3 to 8h at the temperature of 60 to 100 DEG C, and then extracted, washed, dried and subjected to chromatography after being reacted to obtain a target product of indole and the derivatives of indole. Reaction raw materials, the catalyst, the ligand, the alkali and the solvent used in the invention are all industrial commodities, and simple and readily available, wide in sources, cheap in price, and further very stable in performances, and with no need for special storage conditions; in addition, the method for preparing indole and the derivatives of indole disclosed by the invention has the characteristics of low cost, high yield, simple process, less pollution and the like.
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Paragraph 0029-0033
(2017/08/24)
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- C-C Activation by Retro-Aldol Reaction of Two β-Hydroxy Carbonyl Compounds: Synergy with Pd-Catalyzed Cross-Coupling to Access Mono-α-arylated Ketones and Esters
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A retro-aldol reaction of two β-hydroxy compounds in synergy with Pd-catalyzed cross-coupling of aryl halides is reported herein, which produces selectively mono-α-arylated ketones and esters in good yields. This reaction is compatible with a broad range of aryl iodides, bromides, chlorides, and triflates and can tolerate an array of functional groups on the aromatic ring. Ready scale-up of this reaction to gram level is applicable without an appreciable decrease in the reaction yield. Furthermore, concise syntheses of biologically active isocoumarin and indole derivatives have been achieved to greatly demonstrate the synthetic value of this retro-aldol reaction. Finally, the reaction mechanism has been discussed on the basis of experimental observations and DFT computational results. A regulated six-membered-ring transition structure has been located for the key retro-aldol C-C cleavage, which constitutes the rate-determining step of a full catalytic cycle. The concept of C-C activation by retro-aldol reaction may also find applications in other fundamental reactions.
- Zhang, Song-Lin,Yu, Ze-Long
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- Divergent synthesis of indoles, oxindoles, isocoumarins and isoquinolinones by general Pd-catalyzed retro-aldol/α-arylation
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Divergent synthesis of indoles, oxindoles, isocoumarins and isoquinolinones is described in this report by using a general Pd-catalyzed tandem reaction of β-hydroxy carbonyl compounds with aryl halides bearing an ortho-nitro, -ester or -cyano substituent. A key retro-aldol/α-arylation reaction is involved that merges classic Pd cross-coupling chemistry with novel Pd-promoted retro-aldol C-C activation to produce α-arylated ketones or esters. Subsequent intramolecular condensation of the carbonyl with the ortho-synthon gives target heterocycles. The use of common, commercially available and cheap substrates and catalyst system adds additional synthetic advantages to the conceptual significance.
- Zhang, Song-Lin,Yu, Ze-Long
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supporting information
p. 10511 - 10515
(2016/11/18)
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- A practical synthesis of α-aryl methyl ketones via a transition-metal-free Meerwein arylation
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We report herein a simple, scalable, transition-metal-free approach to the synthesis of α-aryl methyl ketones from diazonium tetrafluoroborate salts under mild conditions. This methodology uses easily accessible and nontoxic starting material and was applied to the multi-kilogram-scale preparation of 1-(3-bromo-4-methylphenyl)propan-2-one.
- Molinaro, Carmela,Mowat, Jeffrey,Gosselin, Francis,O'Shea, Paul D.,Marcoux, Jean-Francois,Angelaud, Remy,Davies, Ian W.
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p. 1856 - 1858
(2007/10/03)
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