Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• -selective fluorination of α-bromocarbonyl compounds using a copper/CsF catalyst system (Scheme 32). Tertiary alkyl fluorides could be generated by this fluorination through the assistance of an amide group. From the results, the catalytic cycle of this reaction includes: 1) copper salt induced generation of

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

• heterogeneously catalyzed synthesis of imidazo[1,2-a]pyridines from 3 and ketones 20 has been reported (Scheme 7) [101]. Titania-supported CuCl2 (CuCl2/nano TiO2) played the role of catalyst in this transformation under aerobic conditions. Titania support helped in recyclability of the copper salt to four

• that the presence of copper salt is mandatory for the formation of the fused heterocycle as its absence resulted in the formation of the enaminone only. The imines 118, generated in situ via the loss of nitrogen from azide derivatives, were found to be reactive towards 1,3-dipoles 117 to form diverse

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• copper salt. To confirm the structure of 6, its molecular structure was also analyzed by single-crystal X-ray diffraction (CCDC: 1853770). The molecular structure is demonstrated in Figure 1. Conclusion A variety of 4-(arylselanyl)-1H-pyrazol-5-amines was prepared in a one-pot multicomponent procedure

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• necessary. This means that a dinuclear copper complex – most probably copper(I) acetylide bearing the π-bound copper salt – plays a key role during the cycloaddition step. On the basis of a crossover experiment with an isotopically enriched 63Cu(I) salt it was concluded that the CuAAC involves addition of

Copper-catalyzed asymmetric methylation of fluoroalkylated pyruvates with dimethylzinc

• Kohsuke Aikawa,
• Kohei Yabuuchi,
• Kota Torii and
• Koichi Mikami

Beilstein J. Org. Chem. 2018, 14, 576–582, doi:10.3762/bjoc.14.44

• , CF2Br, and n-CnF2n+1 (n = 2, 3, 8) groups. Results and Discussion Our initial investigation was focused on the methylation of ethyl trifluoropyruvate (1a) with Me2Zn in the presence of a copper salt bearing a chiral bidentate phosphine ligand (Table 1). We were delighted to find that the reaction

• contrast, the chiral product was obtained in 64% yield in the absence of a copper salt but in low enantioselectivity (Table 2, entry 3). Therefore, decreasing the amount of phosphine ligand (2.4 mol %) to less than that of copper salt led to an enhancement of the enantioselectivity to 70% ee (Table 2

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• proceeded via radical intermediates (Scheme 25), which is analogous to Sandmeyer halogenations of diazonium salts. First, the trifluoromethyl copper(I) species is generated from TMSCF3 and copper salt. Then, Cu(I)CF3 transfers one electron to the diazonium salt affording Cu(II)CF3 and a diazo radical

• tetrahydroisoquinoline with DDQ generates dihydroquinoline salt A. Next, CuCF3, generated by the reaction of CuI and CF3TMS/KF, undergoes a nucleophilic addition with A affording the desired products and the copper salt. The generated copper salt would be reused to form CuCF3 in the nucleophilic step again. So, only a

• catalytic amount of copper salt was required in this reaction. The hydrogens on the ortho and para positions of phenols have higher reactivity. Thus, undesired side reactions were often involved in the trifluoromethylation of less substituted phenols, including oxidative dimerization and oligomerization

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• radical cyclisation, to yield the tetralin derivative 12 (Scheme 12) [17]. In 2017, Liu and co-workers focused on N-alkenylurea derivatives 13, and from which they developed an asymmetric radical aminotrifluoromethylation methodology, based on a copper salt/chiral phosphoric acid dual-catalytic system [18

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• presented leading to vicinal trifluoromethyl alcohols. In 2013 Qing and Jiang described the oxytrifluoromethylation of alkenes with hydroxamic acids 32 and CF3SO2Na under Langlois’ conditions with the couple t-BuOOH/copper salt (Scheme 15) [34]. A competitive formation of two radicals, CF3• and the amidoxyl

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• by 1H NMR and 19F NMR for purity. Copper salt precursors were purchased from Sigma-Aldrich. Trimethyl(trifluoromethyl)silane (99% purity) was purchased from SynQuest Labs, Inc. and used without further purification. All other chemicals were verified by 1H NMR for purity and used without further

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• ][78], protonic conduction [79][80], materials with magnetic properties [81][82], or were spread off in polymers to produce nanocomposites [83][84]. Of note, despite the non-chiral nature of compound 13 (Figure 4), it produced, when associated with copper salt, a homochiral non-centrosymmetric

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

• aerobic conditions with copper salt catalysts [67]. For example, when the antipsychotic drug aripiprazole (96) was treated with a catalytic amount of CuI under air or oxygen in DMSO at 120 °C, 2,3-diketopiperazine 97 was produced in 30% yield along with a 15% yield of urea product 98 (Figure 16). This

Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

• Takamichi Wakamatsu,
• Kazunori Nagao,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2015, 11, 2444–2450, doi:10.3762/bjoc.11.265

• )CuCl complex delivered no reaction product (data not shown). The reaction without a ligand resulted in a significantly decreased product yield while the syn selectivity was fairly high (Table 1, entry 7). The use of less expensive CuCl as a copper salt was also effective to produce 4aa in 90% yield

Molecular-oxygen-promoted Cu-catalyzed oxidative direct amidation of nonactivated carboxylic acids with azoles

• Wen Ding,
• Shaoyu Mai and
• Qiuling Song

Beilstein J. Org. Chem. 2015, 11, 2158–2165, doi:10.3762/bjoc.11.233

• the corresponding GC yield (Table 1, entry 14). Copper salt, pyridine and dioxygen were all found to be pivotal to this transformation (Table 1, entries 19–21): without CuBr, no desired product was detected; in the absence of pyridine, the yield of the desired product was reduced to 46% with some

• amides were obtained in good yield in an oxidative protocol with a very broad range of substrates. Subsequent transamidation could be performed using the prepared azole amides and a variety of amines. This reaction has many advantages, in particular the use of an inexpensive copper salt as the catalyst

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• the copper salt with hydrogen sulfide. This methodology has subsequently been employed in a more generic sense as a preparative method for synthesis of acrylic side-chain derivatives of amino acids such as lysine, ornithine, tyrosine and serine [6][7][8], having modified the original technique by

• liberating the acylated derivative from its copper salt using 8-hydroxyquinoline as an organic chelating precipitant [8]. While both useful and creative, the copper chelation procedure carries with it many of the same shortcomings as other types of protective group chemistry. However, by a change of the

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• with azide derivative 1 to yield the copper salt of 3 and a transmetalation reaction gave the intermediate B. We assumed that the pivalate group replaces the acetate group in B and may produce C. The pivalate group in C facilitates the palladium insertion to the C–H bond to give D and subsequent

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• access to various vinyl ethers. A catalytic amount of copper triflate was identified as the significant additive in promoting this transformation. Both aromatic and aliphatic alkynes are suitable substrates with good to excellent yields. Keywords: alkyne; copper salt; diketone; gold catalysis; vinyl

Cu-catalyzed trifluoromethylation of aryl iodides with trifluoromethylzinc reagent prepared in situ from trifluoromethyl iodide

• Yuzo Nakamura,
• Motohiro Fujiu,
• Tatsuya Murase,
• Yoshimitsu Itoh,
• Hiroki Serizawa,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2013, 9, 2404–2409, doi:10.3762/bjoc.9.277

• products in moderate to high yields. The advantage of this method is that additives such as metal fluoride (MF), which are indispensable to activate silyl groups for transmetallation in the corresponding reactions catalyzed by copper salt by using the Ruppert–Prakash reagents (CF3SiR3), are not required

Coupling of C-nitro-NH-azoles with arylboronic acids. A route to N-aryl-C-nitroazoles

• Marta K. Kurpet,
• Aleksandra Dąbrowska,
• Małgorzata M. Jarosz,
• Katarzyna Kajewska-Kania,
• Nikodem Kuźnik and
• Jerzy W. Suwiński

Beilstein J. Org. Chem. 2013, 9, 1517–1525, doi:10.3762/bjoc.9.173

• Materials, Polish Academy of Sciences, M. Curie-Skłodowskiej 34, Zabrze 41-819, Poland 10.3762/bjoc.9.173 Abstract A method for the synthesis of N-aryl-C-nitroazoles is presented. A coupling reaction between variously substituted arylboronic acids and 3(5)-nitro-1H-pyrazole catalyzed by copper salt has

Efficient Cu-catalyzed base-free C–S coupling under conventional and microwave heating. A simple access to S-heterocycles and sulfides

• Silvia M. Soria-Castro and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2013, 9, 467–475, doi:10.3762/bjoc.9.50

• ligands. Thus, different copper-salt-based catalytic systems have been found to be effective for the aryl coupling reactions of ArSH [24][25][26][27][28][29], RSO2Na [30], KSCN [31][32], NH2CSNH2 [33][34], MeCSNH2 [35], KSCSOEt [36][37], Na2S·9H2O [38][39] and sulfur [40][41] as well as the synthesis of

• ), this Cu-catalyzed C–S coupling reaction being highly chemoselective for aryl iodides. In comparison with the already reported procedure for the preparation of S-aryl thioacetates by Pd catalysis [51][56], the methodology herein described has the advantages of using a lower-cost copper salt and a stable

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• reaction and screened several catalysts (Table 1). The cationic Cp*Ir(III) catalyst, which was used in our previous report [23], did not catalyze the reaction at all (Table 1, entry 1). Under copper-salt-free conditions, cationic Cp*Ir(III) catalyst did not give the product, but cationic Cp*Rh(III

Recent advances in carbocupration of α-heterosubstituted alkynes

• Ahmad Basheer and
• Ilan Marek

Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77

• species resulting from the addition of 1 equivalent of alkylmagnesium bromide [R1 = primary, secondary and benzyl groups] to 1 equivalent of copper salt leads, after reaction with electrophiles, to the unique formation of the linear adducts 11 in excellent isolated yields. The intramolecular chelation of

• Grignard from which the organocopper compound was prepared (Scheme 20) [46][47][48][49][50]. Excess of copper salt provides a better stereoisomeric ratio (>90%) [46]. Only the addition of t-BuCu gave a single stereoisomer [51]. In contrast, the copper-catalyzed carbozincation reaction led to a single

N-Arylation of amines, amides, imides and sulfonamides with arylboroxines catalyzed by simple copper salt/EtOH system

• Zhang-Guo Zheng,
• Jun Wen,
• Na Wang,
• Bo Wu and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2008, 4, No. 40, doi:10.3762/bjoc.4.40

• , imides and sulfonamides catalyzed by a copper salt/EtOH system has been developed. In the absence of a base or additive the corresponding N-arylation products were obtained in moderate to excellent yields. Keywords: N-arylation; arylboroxine; copper salt; cross-coupling; ethanol; Introduction The

• ]. Moreover, the reaction rates of these reactions were generally slow, even requiring 3 d for completion [5][6][7]. An attractive alternative to this approach is to develop a simple and efficient catalytic system under mild reaction conditions. Thus, a simple copper salt-catalyzed N-arylation of imides with

• recently in the mechanism of the cross-coupling reaction based on boronic acid. The group of Chan has reported the dynamic behavior of boronic acid in the copper salt catalytic system. The results implied that the active arylating agent such as arylboronic acid in the cross-coupling reaction is indeed its