Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• -catalyzed cross-coupling reactions have laid down the foundation of new C–C bond formations [50][51]. A number of Pd-catalyzed organic reactions viz., C–N coupling, amination and intramolecular amidation, cyclization, and Suzuki–Miyaura coupling [52][53][54][55] have recently been reported in the literature

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

• Xiaoshen Ma and
• Seth B. Herzon

Beilstein J. Org. Chem. 2018, 14, 2259–2265, doi:10.3762/bjoc.14.201

• of the azidation reagent (p-acetamidobenzenesulfonyl azide (p-ABSA)) and additive equivalents (see Supporting Information File 1, Table S1, entries 19–28), the tertiary alkyl azide 4i was obtained in 79% yield (Table 1, entry 9). To broaden the scope of C–N coupling process via HAT, we investigated

Imide arylation with aryl(TMP)iodonium tosylates

• Souradeep Basu,
• Alexander H. Sandtorv and
• David R. Stuart

Beilstein J. Org. Chem. 2018, 14, 1034–1038, doi:10.3762/bjoc.14.90

• -deficient and sterically encumbered aryl groups. Keywords: arylation; C–N coupling; diaryliodonium; hypercoordinate iodine; metal-free; Introduction Imides are important structural units in a range of approved pharmaceuticals and agrochemicals (Scheme 1a) [1]. Despite the general prevalence of imides, N

• transfer [6][7][8][9][10] and Muñiz and co-workers have recently reported an elegant study on sterically controlled C–N coupling of 2,6-disubstituted aryl(phenyl)iodonium salts and imides [11]. We have been investigating the generality of electronically controlled aryl transfer from aryl(trimethoxyphenyl

• )iodonium salts [12][13][14] and describe here the development of a C–N coupling of a phthalimide anion with non-sterically biased aryl groups. The protocol is compatible with ortho-, meta-, and para-substitution on the aryl group and the phthalimide moiety may also provide access to anilines. Results and

Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• radicals, which can yield C–C or C–N coupling products, does not differ in the Kolbe electrolysis from the ratio obtained by the coupling of photochemically produced cyanoalkyl radicals. Optically active carboxylates, which have the asymmetric center at C2 racemize in mixed Kolbe electrolyses [46][47

Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

• Carl J. Mallia,
• Paul M. Burton,
• Alexander M. R. Smith,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1598–1607, doi:10.3762/bjoc.12.156

• proposed a catalytic mechanism and later reported a tin free aryl–amine coupling reaction [6][7]. This major breakthrough made the C–N coupling reaction accessible to a wide range of substrates, including anilines, which did not react very well with the previous conditions. However, despite the

• several examples of literature reported cases where mixtures of regioisomers had been obtained were wrongly assigned. The process described does have certain limitations. For certain nucleophilic substrates no products were obtained when C–N coupling with 4-methoxyphenylboronic acid (17) was attempted

• modification can reliably deliver 0.216 g h−1 of 19 at 81% isolated yield. Conclusion The use of flow chemistry for the C–N coupling through a catalytic Chan–Lam reaction has allowed for a safe and efficient introduction of oxygen through a reverse “tube-in-tube” reactor. Optimisation of the reaction

Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• conjugated alkene. Principally, enamides can also be prepared by the copper-mediated C–N coupling between a vinyl halide 6 and an amide 5 as reported by Ogawa and co-workers in 1991 [6]. Later, the group of Porco showed that copper(I) thiophencarboxylate is a suitable catalyst to promote this reaction in the

• (Table 1). Now, the stage was set to optimize the C–N coupling conditions using amide 13 as coupling partner, the 3-methylbutyric acid located at the terminus of myxovalargin (1). Under the published conditions [13] (vinyl iodide (1.5 equiv), amide (1.0 equiv), CuI (0.6 equiv), Cs2CO3 (2.0 equiv), N,N

• –N cross-coupling approach. Substantial optimization of the reaction conditions and the choice of the protecting group became necessary when the dehydrovaline-containing oligopeptide based on ornithine was synthesized. For the copper-mediated Buchwald C–N coupling reaction, (rac)-trans-N,N-dimethyl

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• reaction, the trifluoroacetamido moiety present in the ortho position of the aryl halides plays an important role in enantiocontrol (Scheme 15). Copper-catalyzed asymmetric aryl C–N coupling through desymmetrization and kinetic resolution strategies In the past, the asymmetric version of aryl C–N/O/S

• enantioselectivity and efficiency. In 2012, Cai et al. [45] developed the first copper-catalyzed asymmetric intramolecular Ullmann C–N coupling reaction through a desymmetrization strategy. The reaction lead to the enantioselective formation of indolines and tetrahydroquinolines in high yields and up to >99% ee

• . reported another type of desymmetrization process, which allowed for the discrimination between two symmetric nucleophilic amine-type groups. Enantiocontrol using such substrates is more difficult in the asymmetric desymmetric aryl C–N coupling reaction because the two nucleophilic groups may serve as good

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• realized via a tandem Ullmann-type C–N coupling of the Ar–X bond and the amino group in 83 as well as the intramolecular amidation which was believed to assist the oxidative formation of the imine C=N bond (Scheme 22). By making use of this cascade synthetic method, Nagarajan et al. [78] finished the

• of the cascade reactions was proposed as shown in Scheme 23 wherein the intermediate 89 generated by Ullmann C–N coupling reaction, the bidentate copper complex 90 and 91 were assumed as the key stages of the cascade reaction. Recently, cascade reactions using analogous o-halobenzenesulfonamide 92

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• 1,2-diazine or imine co-reactants to yield functionalized hydrazones or benzylanilines. SCPC with tertiary amines enabled electron-deficient alkenes to be alkylated and furoquinolinones to be accessed. Primary amines on their own led to self-reactions involving C–N coupling and, with terminal diamines

• in an aqueous dispersion of a Pt-TiO2 catalyst, an interesting self-reaction occurred. Ohtani and co-workers isolated modest yields of secondary amines 13 that were formed via C–N coupling (Scheme 4, top) [48]. Terminal diamines reacted by ring closure resulting in cyclic amines 14; pyrrolidine was

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• excess cannot be considered a disadvantage of the method. Additionally, use of the inexpensive Cu(I) catalyst allows to avoid Buchwald–Hartwig amination [24][25], which employs more expensive Pd-based catalysts for a similar type of C–N coupling reactions. In a typical procedure, 1 equiv of MPTTF 7a, 7b

A simple copper-catalyzed two-step one-pot synthesis of indolo[1,2-a]quinazoline

• Chunpu Li,
• Lei Zhang,
• Shuangjie Shu and
• Hong Liu

Beilstein J. Org. Chem. 2014, 10, 2441–2447, doi:10.3762/bjoc.10.254

• 201203, P. R. China 10.3762/bjoc.10.254 Abstract A convenient CuI/L-proline-catalyzed, two-step one-pot method has been developed for the preparation of indolo[1,2-a]quinazoline derivatives using a sequential Ullmann-type C–C and C–N coupling. This protocol provides an operationally simple and rapid

• Ullmann condensation is a powerful method for C–N coupling [24][25][26], especially the N-arylation of nitrogen-containing heterocycles such as indoles [27][28]. Indolo[1,2-a]quinazoline is a kind of tetracyclic compounds containing the indole motif that has been constructed by intramolecular [3 + 2

• domino cyclization. Based on the previous work for the copper-catalyzed synthesis of 2-amino-1H-indole derivatives and copper-catalyzed N-arylation, we herein report a simple and efficient one-pot method to synthesize indolo[1,2-a]quinazolines by a sequential Ullmann-type C–C and C–N coupling. Compared

Microwave-assisted synthesis of 5,6-dihydroindolo[1,2-a]quinoxaline derivatives through copper-catalyzed intramolecular N-arylation

• Fei Zhao,
• Lei Zhang,
• Hailong Liu,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2013, 9, 2463–2469, doi:10.3762/bjoc.9.285

• tetracyclic architecture is highly desirable for drug discovery. Traditional copper-catalyzed Ullmann-type C–N coupling has been a powerful method to form the carbon–nitrogen bond [15][16][17][18][19]. However, the utility of the reaction is limited by the necessary high temperatures, the requirement of

• , the copper-catalyzed N-arylation has been extensively utilized for C–N coupling, especially for the arylation of N-containing heterocycles such as indoles, imidazoles, indazoles, pyrroles, pyrazoles and triazoles [25][26][27][28] to construct more fused heterocycles. In recent years, several

• moderate yields. In this study, we tried to overcome these limitations by using copper-catalyzed C–N coupling and microwave-assisted organic synthesis, and we present an efficient and practical protocol, which rapidly synthesized 5,6-dihydroindolo[1,2-a]quinoxaline derivatives by copper-catalyzed

Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• mechanisms for the C–N coupling catalyzed by PdCl2(NCMe)2 in homogeneous phase. Supporting Information Supporting Information File 379: Experimental details of preparation, isolation and full characterization of new palladium compounds 3a–c, 4a–c as well as guanidine compounds 5a,b, including IR, NMR, ESIMS

Synthesis of conformationally restricted glutamate and glutamine derivatives from carbonylation of orthopalladated phenylglycine derivatives

• Esteban P. Urriolabeitia,
• Eduardo Laga and
• Carlos Cativiela

Beilstein J. Org. Chem. 2012, 8, 1569–1575, doi:10.3762/bjoc.8.179

• by Beck [18], and this process affords the γ-lactam displayed in Scheme 4. Assuming the mechanism shown in Scheme 1, it seems that, in the absence of any other nucleophile, the intramolecular C–N coupling takes place with concomitant formation of a N,N-dimethylisoindolinonium salt, which undergoes

• reactivity found for 1, and shown in Scheme 3, when compared to related Pd complexes previously reported by us [12], resumed in Scheme 1. Therefore, the synthesis of the methyl (1H)-isoindolin-1-one-3-carboxylates by carbonylation of [Pd(μ-Cl)(C6H4CH(CO2Me)NH2-2)]2 occurs by C–N coupling, irrespective of the

• atom in the carbonylation further. The reaction of 3 with CO (1 atm) in CH2Cl2 at room temperature, that is, in the absence of nucleophiles, occurs with C–N coupling and formation of the methyl 3-oxo-2-((trifluoromethyl)sulfonyl)isoindoline-1-carboxylate (4) in good yields, as shown in Scheme 5 (right

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• results for this Pd-catalyzed tandem Sonogashira/double C–N coupling reaction were obtained when Pd(OAc)2 was used as the catalyst along with a bulky bidentate phosphine ligand such as Xantphos in the presence of Cs2CO3 as base. Most likely, the reaction proceeds through a Pd-catalyzed Sonogashira

• -alkynylindoles through a Pd-catalyzed Sonogashira/double C–N coupling reaction. Synthesis of indoles through a Pd-catalyzed sequential alkenyl amination/C-arylation/N-arylation. Synthesis of N-aryl-2-benzylpyrrolidines through a sequential N-arylation/carboamination reaction. Synthesis of phenothiazine