62128-31-8Relevant academic research and scientific papers
Selective PdII-Catalyzed Acylation of Pyrrole with Aldehydes. Application to the Synthesis of Celastramycin Analogues and Tolmetin
Santiago, Carlos,Rubio, Ibon,Sotomayor, Nuria,Lete, Esther
, p. 4284 - 4295 (2020/05/25)
The PdII-catalyzed C-2 acylation of pyrrole with aldehydes in the presence of TBHP as oxidant has been studied for the synthesis of di(hetero)aryl ketones. The use of 2-pyrimidine as directing group leads to 2-acylpyrroles in moderate to good yields, although 2,5-diacylpyrroles are obtained as by products. This side-reaction could be avoided using 3-methy-2-pyridine as directing group, obtaining selectively 2-acylpyrroles. The reaction has been extended to a series of aromatic and heteroaromatic aldehydes, obtaining the best results with electron rich aromatic aldehydes. The methodology has been applied in the synthesis of pyrrolomycin alkaloid Celastramycin analogues and for an improved synthesis of Tolmetin, a nonsteroidal anti-inflammatory drug.
Aroylation of Electron-Rich Pyrroles under Minisci Reaction Conditions
Laha, Joydev K.,Kaur Hunjan, Mandeep,Hegde, Shalakha,Gupta, Anjali
, p. 1442 - 1447 (2020/02/22)
The development of Minisci acylation on electron-rich pyrroles under silver-free neutral conditions has been reported featuring the regioselective monoacylation of (NH)-free pyrroles. Unlike conventional Minisci conditions, the avoidance of any acid that could result in the polymerization of pyrroles was the key to success. The umpolung reactivity of the nucleophilic acyl radical, generated in situ from arylglyoxylic acid, could help explain the mechanism of product formation with electron-rich pyrroles. Alternatively, the nucleophilic substitution of the acyl radical on the electron-deficient pyrrole radical cation is proposed.
A general approach to intermolecular carbonylation of arene C-H bonds to ketones through catalytic aroyl triflate formation
Kinney, R. Garrison,Tjutrins, Jevgenijs,Torres, Gerardo M.,Liu, Nina Jiabao,Kulkarni, Omkar,Arndtsen, Bruce A.
, p. 193 - 199 (2018/02/06)
The development of metal-catalysed methods to functionalize inert C-H bonds has become a dominant research theme in the past decade as an approach to efficient synthesis. However, the incorporation of carbon monoxide into such reactions to form valuable ketones has to date proved a challenge, despite its potential as a straightforward and green alternative to Friedel-Crafts reactions. Here we describe a new approach to palladium-catalysed C-H bond functionalization in which carbon monoxide is used to drive the generation of high-energy electrophiles. This offers a method to couple the useful features of metal-catalysed C-H functionalization (stable and available reagents) and electrophilic acylations (broad scope and selectivity), and synthesize ketones simply from aryl iodides, CO and arenes. Notably, the reaction proceeds in an intermolecular fashion, without directing groups and at very low palladium-catalyst loadings. Mechanistic studies show that the reaction proceeds through the catalytic build-up of potent aroyl triflate electrophiles.
An Electrophilic Approach to the Palladium-Catalyzed Carbonylative C-H Functionalization of Heterocycles
Tjutrins, Jevgenijs,Arndtsen, Bruce A.
supporting information, p. 12050 - 12054 (2015/10/05)
A palladium-catalyzed approach to intermolecular carbonylative C-H functionalization is described. This transformation is mediated by PtBu3-coordinated palladium catalyst and allows the derivatization of a diverse range of heterocycles, including pyrroles, indoles, imidazoles, benzoxazoles, and furans. Preliminary studies suggest that this reaction may proceed via the catalytic formation of highly electrophilic intermediates. Overall, this provides with an atom-economical and general synthetic route to generate aryl-(hetero)aryl ketones using stable reagents (aryl iodides and CO) and without the typical need to exploit pre-metalated heterocycles in carbonylative coupling chemistry.
Acylation of pyrroles and their free (N-H)-derivatives via palladium-catalyzed carbopalladation of nitriles
Jafarpour, Farnaz,Hazrati, Hamideh,Darvishmolla, Masoumeh
supporting information, p. 3784 - 3788 (2015/02/19)
An efficient regioselective synthesis of 2-acylpyrroles via palladium-catalyzed addition of pyrroles with benzonitriles and subsequent hydrolysis is developed. The direct acylation reaction of protected as well as (NH)-free pyrroles proceeded smoothly to
Vilsmeier-Haack preparation of 2-acylpyrroles using bis(trichloromethyl) carbonate and N,N-dimethylacylamines
Shi,Su,Shan
, p. 1019 - 1021 (2007/10/03)
A series of 2-acylpyrroles were synthesized by using bis(trichloromethyl) carbonate and N,N-dimethylacylamines as Vilsmeier-Haack reagents under mild conditions in good yields.
Regiospecific C-acylation of pyrroles and indoles using N-acylbenzotriazoles
Katritzky, Alan R.,Suzuki, Kazuyuki,Singh, Sandeep K.,He, Hai-Ying
, p. 5720 - 5723 (2007/10/03)
Reactions of pyrrole (2) or 1-methylpyrrole (4) with readily available N-acylbenzotriazoles 1a - g (RCOBt, where R = 4-tolyl, 4-nitrophenyl, 4-diethylaminophenyl, 2-furyl, 2-pyridyl, 2-indolyl, or 2-pyrrolyl) in the presence of TiCl4 produced 2
Acid-Mediated Rearrangement of Acylpyrroles
Carson, John R.,Davis, Nancy M.
, p. 839 - 843 (2007/10/02)
N-Alkyl-2-acylpyrroles are converted by strong anhydrous acid to 1-alkyl-3-acylpyrroles.An equilibrium mixture of 2- and 3-acylpyrrole is produced by treatment of a 2- or 3-acyl NH pyrrole with acid.Pyrrolecarboxaldehydes similarly afford isomeric mixtures.A cross-ring migration, 7->8, is observed when the adjacent position is blocked.The mechanism of acid-mediated rearrangement of acylpyrroles is discussed.
Preparation of β-acyl pyrroles
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, (2008/06/13)
A process for rearranging α-acyl pyrroles to β-acyl pyrroles which comprises reacting the former with an excess of a strong, anhydrous, non-oxidizing acid, preferably with heating.
