- 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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- Highly Active Manganese-Mediated Acylation of Alcohols with Acid Chlorides or Anhydrides
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To explore further the practical uses of highly active manganese (Mn?), a variety of alcohols were treated with Mn?, and the resulting complexes were coupled with acid chlorides and/or acetic anhydride in the absence of any extra catalyst. The subsequent reactions took place smoothly under mild conditions, providing the corresponding O-acylation products in good to excellent isolated yields.
- Joo, Seong-Ryu,Youn, Young-Jin,Hwang, Young-Ran,Kim, Seung-Hoi
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p. 2665 - 2669
(2017/10/07)
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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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- Inhibition of reverse transcriptase and Taq DNA polymerase by compounds possessing the coumarin framework
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Coumarin derivatives were prepared using natural products isolated from plants belonging in the Pterocaulon genus (Asteraceae) and commercial drugs. Some molecules have displayed interesting activity against myeloid murine leukemia virus-reverse transcriptase (MMLV-RT) (compounds 20 and 28 produced inhibition with IC50 values of 38.62 and 50.98 μM, respectively) and Taq DNA polymerase (analogues 13 and 14 produced inhibition with IC 50 values of 48.08 and 57.88 μM, respectively). Such inhibitors may have importance as antiretroviral chemotherapeutic agents and also in the development of anticancer drugs.
- Garro Hugo,Manzur Jimena,Ciuffo Gladys,Tonn Carlos,Pungitore Carlos
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p. 760 - 764
(2014/02/14)
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- Synthesis and photooxygenation of furo[3,2-c]coumarin derivatives as antibacterial and DNA intercalating agent
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Syntheses of 2,3-dimethyl-4H-furo[3,2-c]coumarin and 3-phenyl-4H-furo[3,2- c]coumarin as angular furocoumarins were carried out through Williamson reaction of 4-hydroxycoumarin with α-haloketones followed by cyclization. Photooxygenation of the synthesized furocoumarin derivatives was performed and the photoproducts were isolated and characterized. The affinity of 2,3-dimethyl-4H-furo[3,2-c]coumarin towards DNA and the antibacterial activity were evaluated and compared with 8-methoxypsoralen (8-MOP). Syntheses of 2,3-dimethyl-4H-furo[3,2-c]coumarin and 3-phenyl-4H-furo[3,2-c]coumarin as angular furocoumarins were carried out through Williamson reaction of 4-hydroxycoumarin with α-haloketones followed by cyclization. Photooxygenation of the synthesized furocoumarin derivatives was performed and the photoproducts were isolated and characterized. The affinity of 2,3-dimethyl-4H-furo[3,2-c]coumarin towards DNA and the antibacterial activity were evaluated and compared with 8-methoxypsoralen (8-MOP). Copyright
- Al-Sehemi, Abdullah G.,El-Gogary, Sameh R.
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p. 316 - 320
(2012/04/23)
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- SmCl3-catalyzed C-acylation of 1,3-dicarbonyl compounds and malononitrile
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(Chemical Equation Presented) A recyclable, convenient, and efficient catalytic system for C-acylation of 1,3-dicarbonyl compounds and malononitrile with acid chlorides has been developed, giving moderate to excellent yields under mild conditions. This is the first catalytic example of such reactions. In addition, by applying this protocol as the key step, 3,5-disubstituted-1H- pyrazole-4-carboxylate can easily be synthesized in high yields in a one-pot procedure.
- Shen, Quansheng,Huang, Wen,Wang, Jialiang,Zhou, Xigeng
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p. 4491 - 4494
(2008/03/12)
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- Efficient synthesis of trisubstituted [1]benzopyrano[4,3-b]pyrrol-4(1H)-one derivatives from 4-hydroxycoumarin
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Various trisubstituted [1]benzopyrano[4,3-b]pyrrol-4(1H)-one derivatives have been synthesized from 4-hydroxycoumarin with a 30-40% yield over six steps. The key step of the synthesis is a base-promoted intramolecular cyclization of enamines 5, followed by dehydration to generate the fused pyrrole ring.
- Liao, Yuan-Xiu,Kuo, Pei-Yu,Yang, Ding-Yah
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p. 1599 - 1602
(2007/10/03)
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- Synthesis and reactions of 3-aroyl derivatives of 4-hydroxy-2-quinolones and 4-hydroxycoumarin
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3-Aroyl-4-hydroxy-2-quinolones 4 and 11 can be synthesized starting with 1 or 9 via Fries rearrangement of the corresponding esters 3 and 10, catalyzed by potassium cyanide and 18-crown-6. A one pot procedure is presented in which the esters do not need to be isolated. Reduction of the aryl ketones 4 and 11 with zinc dust leads to the benzyl derivatives 5 and 12. Reaction of the aryl ketones 4 and 11 with hydroxylamine and subsequent heating of the crude product leads via thermal Beckmann rearrangement and dehydration to oxazoloquinolones 7 and 14. 2-Aroyloxypyrido[1,2-a]pyrimidin-4-ones 17 and 20 could not be converted to the corresponding ketones by Fries rearrangement.
- Kappe, Thomas,Schnell, Barbara
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p. 663 - 670
(2007/10/03)
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