Mild, base-free copper-catalyzed N-arylations of heterocycles using potassium aryltrifluoroborates in water under air

Joubert, Nicolas; Baslé, Emmanuel; Vaultier, Michel; Pucheault, Mathieu

doi:10.1016/j.tetlet.2010.03.118

Cited by 25 publications

(13 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Several methods have been developed for the arylation of imidazoles; for instance, the Ullman53 and Buchwald54 coupling reactions. These methodologies have been applied in the arylation of imidazoles with aryl halides,55,56 aryllead(IV) reagents,57 arylboronic acids,58,59 and trifluoroaryl borates 60. Despite the tautomeric equilibrium of imidazoles, several N‐arylation reactions were reported to have good chemoselectivities toward the ϵ‐nitrogen atom of backbone‐functionalized imidazoles 55,57.…”

Section: Resultsmentioning

confidence: 99%

Allylpalladium(II) Histidylidene Complexes and Their Application in Z‐Selective Transfer Semihydrogenation of Alkynes

et al. 2015

View full text Add to dashboard Cite

We have studied the use of amino acid histidine as a precursor for N-heterocyclic carbene (NHC) ligands. This natural amino acid possesses an imidazole substituent, which makes it an interesting NHC precursor that contains both an acid and an amino functionality. These functionalities may be used for further tuning of NHC complexes. We have developed routes for the synthesis of symmetric and dissymmetric alkyl, benzyl, and aryl-substituted histidinium salts.[a] Molecular Scheme 3. Synthesis of symmetrically substituted benzylic histidinium bromides. The Cyclic Urea ApproachSubsequently, we employed the cyclic urea approach, which allows the synthesis of dissymmetrically substituted histidinium salts and further tuning of the properties of the NHC metal complex. This is not straightforward because histidine has two tautomeric forms, which means that the δ-and the ε-nitrogen of the imidazole possess both imine and amine character (compound 4, Scheme 5). [20] Therefore, mixtures of regioisomers are obtained when the imidazole is reacted with one equivalent of an electrophile. To obtain the desired dissymmetrically substituted histidinium salts, we applied a route based on the report by Hodges and Chivikas, [17] and was improved by Brégeon et al. [30] (Scheme 4). Scheme 4. The cyclic urea route toward dissymmetrically substituted histidinium salts.This cyclic urea route induces regioselectivity because only the six-membered cyclic urea 5 can be formed. The second nitrogen atom can then be functionalized selectively through nucleophilic substitution. Subsequently, the R 1functionalized urea compounds can be ring-opened by reaction with an alcohol, which liberates the δ-nitrogen atom of the imidazole, and provides a carbamate-protected amine. The use of tBuOH affords the Boc-protected histidine, Eur. J. Inorg. Chem. 2015, 982-996

show abstract

Section: Resultsmentioning

confidence: 99%

Allylpalladium(II) Histidylidene Complexes and Their Application in Z‐Selective Transfer Semihydrogenation of Alkynes

et al. 2015

View full text Add to dashboard Cite

show abstract

“…13 C-NMR (150 MHz, CDCl3), δ (ppm): 56.2 (C4-Pz), 127-134 (6C-Ph), 141 (C3, C5-Pz). İyodo-1-fenil-1H-pirazolün (Ph-IPz) sentez şeması.…”

unclassified

“…Birçok bakır/ligant kombinasyon reaksiyonlarının nispeten yumuşak koşullar altında gerçekleştirdiği bilinmesine rağmen, ligant içermeyen ve "yeşil" çözücülerle ya da çözücüsünden arındırılmış daha basit katalizör sistemleri bulmaya ihtiyaç duyulmaktadır.Bu çalışmada literatürdeki yönteme göre sentezlenen[11] 4-iyodo pirazollerin fenil boronik asit ile Cu2O katalizörlüğünde N-arilasyonları gerçekleştirildi. N-arilleme reaksiyonu klasik Ullmann reaksiyonunu geliştirerek daha ılıman koşullarda oluşmasına katkıda sağlamak amacıyla ilave ligant veya baz olmadan, atmosferik koşullarda, oda sıcaklığında metanol içerisinde karıştırılarak literatürdeki yönteme göre uyarlanarak sentezlenmiştir[12][13][14][15]. Bu yöntemle pirazol türevleri olan Ph-IDMPz ve Ph-IPz bileşiklerinin sentezi ilk defa bu çalışma ile gerçekleştirilmiş oldu.2.…”

unclassified

“…Reaksiyonlarda ve saflaştırma işlemlerinde çözücü olarak metanol veya diklorometan kullanılmıştır. TLC (Gel 60 F254 TLC Alüminyum tabakalı 20x20 cm) kullanılarak reaksiyonlar takip edilmiştir.Sentezlenen bileşiklerin 1 H NMR,13 C NMR spektrumları, Agilent marka 600 MHz'lik frekansta, 14.1 Tesla alan gücüne sahip Premium Compact NMR cihazı ile yapıldı. FT-IR spektrumları Perkin Elmer Spectrum 100 FT-IR spektrometresi ile ATR tekniği kullanılarak 650-4000 cm -1 aralığında kaydedildi.…”

unclassified

“…Bileşiklerin NMR ve FT-IR spektrumunda hem pirazole hem de fenil grubuna ait karakteristik pikler gözlenmiştir. Elde edilen Ph-IPz ve Ph-IDMPz bileşiklerinin 1 H-NMR spektrumlarında N-H proton piklerinin görülmemesi fenil grubunun pirazole NH'dan bağlandığının bir göstergesidir 13. C-NMR spektrumlarında 4sübstitüe pirazoller için belirleyici olan C4 karbon piklerindeki kaymalar da bileşiklerin yapılarını doğrulamaktadır.…”

unclassified

See 2 more Smart Citations

Ullmann Type N-Arylation Reactions of Iodo Pyrazoles with Phenyl Boronic Acid in Cu2O Catalyst

Hinis

Menteş

2019

Aksaray University Journal of Science and Engineering

View full text Add to dashboard Cite

Ullmann type reactions are one of the most effective methods to carry out the N-arylation of the pyrazole using copper catalyst. The Ullmann reaction carried out by conventional methods occur under hard reaction conditions using copper reagents at stoichiometric ratio and at high temperatures. With the development of more efficient copper catalysts, studies in this field have been continued and very efficient copper/ligand systems have been developed under mild conditions. Although it is known that many of copper / ligand system reactions are carried out under relatively mild conditions to increase the efficiency of Ullmann type reactions, in recent years, studies have been made on simpler catalyst systems which are ligand free and "green" solvents or solvent free. In this study, in order to contribute to N-arylation of pyrazoles in mild conditions, 4-Iodo-1phenyl-1H-pyrazole (Ph-IPz) and 4-iodo-3,5-dimethyl-1-phenyl-1H-pyrazole (Ph-IDMPz) compounds were synthesized according to the methods adapted from literature with N-arylation reaction of 4-Iodo-1H-pyrazole (4-IP) or 4-iodo-3,5-dimethyl-1H-pyrazole (4-IDMPz) with phenyl boronic acid in the prences of Cu2O catalyst. N-Arylation reactions of 4-iodopyrazols with phenyl boronic acit were carried out the presence of Cu2O catalyst, at atmospheric conditions, at room temperature, in methyl alcohol and without the use of any base and ligand. In this way , the synthesis of Ph-IPz and Ph-IDMPz was carried out for the first time with Ullmann reaction under the milder conditions. Synthesized ligands Ph-IPz and Ph-IDMPz were characterized by FT-IR, NMR and GC-MS mass spectra. The NMR and FT-IR spectra of the compounds showed characteristic peaks of both the pyrazole and the phenyl group. The absence of N-H proton peaks in the 1 H-NMR spectra of the obtained Ph-IP 2 and Ph-IDMP 2 compounds indicates that the phenyl group is attached from the pyrazole NH. The shifts in the C4 carbon peaks which are determinant for 4substituted pyrazoles in the 13C-NMR spectra also confirm the structure of the compounds.

show abstract

Alternative and Emerging Reagents for the Arylation of Heteronucleophiles

Neuville¹

2013

Copper‐Mediated Cross‐Coupling Reactions

View full text Add to dashboard Cite

Mild, base-free copper-catalyzed N-arylations of heterocycles using potassium aryltrifluoroborates in water under air

Cited by 25 publications

References 44 publications

Allylpalladium(II) Histidylidene Complexes and Their Application in Z‐Selective Transfer Semihydrogenation of Alkynes

Allylpalladium(II) Histidylidene Complexes and Their Application in Z‐Selective Transfer Semihydrogenation of Alkynes

Ullmann Type N-Arylation Reactions of Iodo Pyrazoles with Phenyl Boronic Acid in Cu2O Catalyst

Alternative and Emerging Reagents for the Arylation of Heteronucleophiles

Contact Info

Product

Resources

About