- Tropolonate salts as acyl-transfer catalysts under thermal and photochemical conditions: Reaction scope and mechanistic insights
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Acyl-transfer catalysis is a frequently used tool to promote the formation of carboxylic acid derivatives, which are important synthetic precursors and target compounds in organic synthesis. However, there have been only a few structural motifs known to efficiently catalyze the acyl-transfer reaction. Herein, we introduce a different acyl-transfer catalytic paradigm based on the tropolone framework. We show that tropolonate salts, due to their strong nucleophilicity and photochemical activity, can promote the coupling reaction between alcohols and carboxylic acid anhydrides or chlorides to give products under thermal or blue light photochemical conditions. Kinetic studies and density functional theory calculations suggest interesting mechanistic insights for reactions promoted by this acyl-transfer catalytic system.
- Mai, Binh Khanh,Koenigs, Rene M.,Nguyen, Thanh Vinh,Lyons, Demelza J.M.,Empel, Claire,Pace, Domenic P.,Dinh, An H.
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p. 12596 - 12606
(2020/11/18)
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- Palladium-catalyzed external-CO-free carbonylation of aryl bromides using 2,4,6-trichlorophenyl formate
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A practical Pd-catalyzed carbonylation of (hetero)aryl bromides using a crystalline carbon monoxide (CO) surrogate, 2,4,6-trichlorophenyl formate (TCPF), was developed. This reaction proceeds without the slow addition technique that was previously required and with a low catalyst loading (1mol%). The utility of this Pd-catalyzed external-CO-free carbonylation using TCPF was demonstrated in the synthesis of a histone deacetylase inhibitor.
- Konishi, Hideyuki,Sekino, Tomoyuki,Manabe, Kei
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p. 562 - 567
(2018/05/07)
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- 4-(N,N -dimethylamino)pyridine hydrochloride as a recyclable catalyst for acylation of inert alcohols: Substrate scope and reaction mechanism
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4-(N,N-Dimethylamino)pyridine hydrochloride (DMAP·HCl), a DMAP salt with the simplest structure, was used as a recyclable catalyst for the acylation of inert alcohols and phenols under base-free conditions. The reaction mechanism was investigated in detail for the first time; DMAP·HCl and the acylating reagent directly formed N-acyl-4-(N′,N′-dimethylamino) pyridine chloride, which was attacked by the nucleophilic substrate to form a transient intermediate that released the acylation product and regenerated the DMAP·HCl catalyst.
- Liu, Zhihui,Ma, Qiaoqiao,Liu, Yuxiu,Wang, Qingmin
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supporting information
p. 236 - 239
(2014/01/23)
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- Alkoxycarbonylation and phenoxycarbonylation reactions catalyzed by a palladium(II) organometallic complex encaged in y zeolite
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Catalytic routes for synthesis of alkyl benzoates by alkoxycarbonylation reactions and aryl benzoates by phenoxycarbonylation reactions of aryl iodides are described using a palladium-1,10-phenanthroline complex encaged in Y zeolite. Moderate to excellent yields (40-99 %) of various benzoates were obtained at low Pd loadings of 0.6 mol%. The catalyst could be effectively removed from the reaction mixture by a simple filtration process and was reused four times with only minor loss of activity. Furthermore, its catalytic activity was further highlighted by a comparison with another two supported Pd catalysts. The protocol has the advantages of easy handing, moderate to excellent yield, and catalyst recyclability. Graphical Abstract: [Figure not available: see fulltext.]
- Mei, Hui,Xiao, Se,Zhu, Tianwu,Lei, Yizhu,Li, Guangxing
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p. 443 - 450
(2014/05/20)
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- Trichlorophenyl formate: Highly reactive and easily accessible crystalline CO surrogate for palladium-catalyzed carbonylation of aryl/alkenyl halides and triflates
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The high utility of 2,4,6-trichlorophenyl formate, a highly reactive and easily accessible crystalline CO surrogate, is demonstrated. The decarbonylation with NEt3 to generate CO proceeded rapidly at rt, thereby allowing external-CO-free Pd-catalyzed carbonylation of aryl/alkenyl halides and triflates. The high reactivity of the CO surrogate enabled carbonylation at rt and significantly reduced the quantities of formate to near-stoichiometric levels. The obtained trichlorophenyl esters can be readily converted to a variety of carboxylic acid derivatives in high yields.
- Ueda, Tsuyoshi,Konishi, Hideyuki,Manabe, Kei
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supporting information
p. 5370 - 5373,4
(2012/12/12)
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