Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons

• Goki Hirata,
• Yu Yamane,
• Naoya Tsubaki,
• Reina Hara and
• Takashi Nishikata

Beilstein J. Org. Chem. 2020, 16, 502–508, doi:10.3762/bjoc.16.45

• could suggest new aspects of alkyne transformations in a copper catalyzed alkyl radical reaction system. Substrate scope of 1 and 2. aConducted at 80 °C for 24 h in MeCN with CuBr (10 mol %), 1,10-Phen (20 mol %), Cs2CO3 (4.0 equiv), NaI (2.0 equiv), 1 (3.0 equiv) and 2 (1.0 equiv). Yields were

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• ) [25]. This copper-catalyzed photocatalytic reduction generated an aryl radical that was trapped with various allylating reagents. First, the phenyl radical generated from the corresponding diphenyliodonium salt was added to various allyl sulfones substituted in the 2-position. The products were

• 2012, Collins and co-workers described a copper-catalyzed photocyclization to synthesize [5]helicene (Scheme 29) [43]. Using the in situ-formed [Cu(I)(dmp)(xantphos)]BF4 (25 mol %) in the presence of iodine and propylene oxide as the oxidant system under visible light irradiation, [5]helicene was

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• (diphenylphosphino)-1,1'-binaphthyl (BINAP) with a greater π-density and sterically demanding groups, have been extensively used in catalytic reactions [94]. Wang et al. [95] reported a copper-catalyzed phosphorylation in the synthesis of an oxazolylindolylphosphine as shown in Scheme 18. The intermediate amide 97

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• -promoted and copper-catalyzed processes for the introduction of SeCF3 groups Copper(I) trifluoromethylselenolate complexes Copper(I) trifluoromethylselenolate was first prepared in 1985 by the group of Yagupolskii [12]. Then, CuSeCF3·DMF was tested in the trifluoromethylselenolation of (hetero)aryl iodides

• , this species is in an equilibrium with the −SeCF3 anion. As proposed by Hor and Weng, Deng and Xiao also suggested that CuSeCF3 was the active species in the mechanism. In 2016, the group of Rueping described a sequential copper-catalyzed selenocyanation of aryldiazonium salts, followed by

• . Trifluoromethylselenolation of diazoacetates and diazonium salts with Me4NSeCF3 by the group of Goossen. Trifluoromethylselenolation with ClSeCF3 by the group of Tlili and Billard. Trifluoromethylselenolation with TsSeCF3 by the group of Tlili and Billard. Copper-catalyzed synthesis of a selenylated analog 30 of Pretomanid

Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors

• Delphine Pichon,
• Jennifer Morvan,
• Christophe Crévisy and
• Marc Mauduit

Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24

• Delphine Pichon Jennifer Morvan Christophe Crevisy Marc Mauduit Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR – UMR 6226, F-35000 Rennes, France 10.3762/bjoc.16.24 Abstract The copper-catalyzed enantioselective conjugate addition (ECA) of organometallic

• -acyloxazolidinones, N-acylpyrrolidinones, amides, and N-acylpyrroles have been scarcely investigated in Cu ECA despite their usefulness for postfunctionalizations. This tutorial review aims to describe the early examples and recent advances in copper-catalyzed asymmetric conjugate additions of dialkylzinc, Grignard

• , or trialkylaluminium reagents toward those challenging substrates and their fruitful application in the total synthesis of natural products. Review Enantioselective conjugate addition to challenging Michael acceptors Copper-catalyzed ECA to α,β-unsaturated aldehydes Nowadays, β-substituted enals

Combination of multicomponent KA² and Pauson–Khand reactions: short synthesis of spirocyclic pyrrolocyclopentenones

• Riccardo Innocenti,
• Elena Lenci,
• Gloria Menchi and
• Andrea Trabocchi

Beilstein J. Org. Chem. 2020, 16, 200–211, doi:10.3762/bjoc.16.23

• . Following our interest to DOS as a synthetic strategy for the generation of molecular scaffolds according to a couple/pair approach [45][46][47], we reasoned to combine the copper-catalyzed ketone–amine–alkyne (KA2) multicomponent coupling reaction [48] with the Pauson–Khand cycloaddition as the pairing

• was achieved, suggesting a role of the aromatic ring in activating the alkyne towards the copper-catalyzed process (Table 1, entries 3 and 4), as previously reported in other works [54]. Use of cyclopentanone, thus varying the ring size of the cyclic ketone, resulted in the conversion to the title

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• . The synergistic palladium/copper-catalyzed reaction of aromatic aldehydes, allylic carbonates, and a silylboronate produces the corresponding homoallylic alcohol derivatives. This process involves the catalytic formation of a nucleophilic α-silyloxybenzylcopper(I) species and the subsequent palladium

• ) afforded the linear allylation product 3aa with complete regioselectivity. The symmetric secondary allylic carbonate was converted to the corresponding homoallylic alcohol derivative in 50% yield (3af). To gain understanding into the mechanism of this synergistic palladium/copper-catalyzed allylic cross

• summary, we developed an umpolung strategy for catalytically formed α-alkoxyalkyl anions from aromatic aldehydes for the use in allylic cross-coupling reactions. The synergistic palladium/copper-catalyzed reaction of aromatic aldehydes, allylic carbonates, and a silylboronate delivered the homoallylic

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• methods for carbamothioates have been reported. These include reactions of chlorothioformates with amines [14], thiocarbonyl benzotriazoles with alcohols [15], copper-catalyzed reactions of α-substituted stannanes with carbamothioates [16], reactions of isothiocyanates with alcohols [6][17], and reactions

Halogen-bonding-induced diverse aggregation of 4,5-diiodo-1,2,3-triazolium salts with different anions

• Xingyu Xu,
• Shiqing Huang,
• Zengyu Zhang,
• Lei Cao and
• Xiaoyu Yan

Beilstein J. Org. Chem. 2020, 16, 78–87, doi:10.3762/bjoc.16.10

• candidates for XB donors, which is mainly due to the ease of preparation via a copper-catalyzed click reaction between azide and alkyne [38][39]. 1,2,3-Triazoles and 1,2,3-triazolium-based XB activators have been found applications in catalytic reactions [40][41] and anion recognition [42]. Recently, we

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• important transformation. Herein we report a study on the palladium-catalyzed copper- and added base-free Sonogashira coupling reactions to synthesize various acetylenes in γ-valerolactone-based ionic liquids under mild conditions. Results and Discussion We recently demonstrated that copper-catalyzed

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• catalytic hydrogenation to 4 followed by protection with TBDMS to give 5 in 63% yield for three steps. The synthesis of the other half of the photochrome started with bromination of difluorinated aniline to give 6 followed by copper-catalyzed cyanation to 7 in 62% overall yield. Diazonization of 7 with

• nitrosonium tetrafluoroborate gave 8 (54% yield). The two parts of the chromophore were coupled starting by treatment of 5 with n-butyllithium at −78 °C, which was coupled in situ with 8 to AB 9 (17% yield). Copper-catalyzed hydration of 9 gave amide 10, which was treated with TBAF to alcohol 11 in 42

Fluorinated maleimide-substituted porphyrins and chlorins: synthesis and characterization

• Valentina A. Ol’shevskaya,
• Elena G. Kononova and
• Andrei V. Zaitsev

Beilstein J. Org. Chem. 2019, 15, 2704–2709, doi:10.3762/bjoc.15.263

• 1,2,3-triazole heterocycles via the copper-catalyzed azide–alkyne cycloaddition reaction (CuAAC) between alkynes and azides, developed independently by Sharpless [41] and Meldal [42]. In addition to the applications of triazoles as pharmacophores in the potential biologically active molecules, these

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

• phase-transfer copper catalyst (Scheme 27). Notably, with 10 mol % of (IPr)CuOTf, full conversion can be accomplished in 10 minutes at 45 °C. Allylic fluorination: In 2013, there is an example of a copper-catalyzed fluorination of internal allylic bromides (Scheme 28). In Liu’s study, this approach was

• (Scheme 31a) [74]. Che and co-workers [75] achieved a similar α-fluorination of β-ketoesters and N-Boc-oxindoles (Scheme 31b). Compared with Du’s method, Che employed both AgClO4 and chiral iron(III)-salan complexes as the catalyst. In 2016, the group of Nishikata [76] described a copper-catalyzed site

• five and six-membered ring β-ketoesters were converted to the corresponding products in high yields and enantioselectivities (Scheme 56). In 2018, the first example for the copper-catalyzed stereospecific trifluoromethylation of secondary propargyl sulfonates was described by the group of Zhang [116

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• Ullmann-type coupling to give aryl azide 2, which readily reacted with phenylacetylene in a copper-catalyzed Huisgen 1,3-dipolar cycloaddition to give 1,2,3-triazole 3 (Scheme 1). The formation of the ruthenacycle was then achieved using Albrecht’s method involving regioselective methylation of triazole 3

• our case column chromatography was only used once (to purify the monoazidocalix[4]arene 7), whilst the other procedure needed chromatography at each step. Introduction of the triazole moiety onto the upper rim of the calix[4]arene was then achieved with a copper-catalyzed Huisgen 1,3-dipolar

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• new C–N bonds in the presence of transition metal catalysts [25][26][27][28][29][30][31][32][33][34]. Tang and Jiao reported copper catalyzed C–C single bond cleavage and C–N bond formation [35]. However, the transition metal catalysts and additives employed in these transformations are toxic and

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

• been given much attention in various research fields, such as the discovery of lead compounds in medicinal chemistry, or combinatorial chemistry [95][96]. Copper-catalyzed synthetic protocols Ghosh and Mishra [97] have successfully reported the synthesis of imidazo[1,2-a]pyridines in a three-component

• process oxygen (air) acts as oxidant which resulted in the oxidation of Cu(II) to Cu(III) and Cu(I) back to Cu(II) (Scheme 28). A copper-catalyzed oxidative cyclization approach has been used for the synthesis of formyl-substituted imidazo[1,2-a]pyridines 89. The remarkable feature of this method was the

• , perhaps because the α,β-unsaturated double bond affected the iodination. Mohan et al. successfully developed an efficient copper-catalyzed aerobic oxidative amination of C(sp3)–H bonds to synthesize imidazo[1,5-a]pyridine derivatives [122]. The reaction was also applicable to amino acid derivatives, as

Synthesis of 9-O-arylated berberines via copper-catalyzed C_Ar–O coupling reactions

• Qiaoqiao Teng,
• Xinhui Zhu,
• Qianqian Guo,
• Weihua Jiang,
• Jiang Liu and
• Qi Meng

Beilstein J. Org. Chem. 2019, 15, 1575–1580, doi:10.3762/bjoc.15.161

• 9-O-phenylene-bridged berberine dimer (5) was synthesized by copper-catalyzed cross-coupling of tetrahydroberberrubine and aryl iodides, followed by oxidation with I2. Keywords: arylation; berberines; cross-coupling; copper; lipophilicity; structural modification; Introduction Berberine (BBR) is a

• of 5. Conclusion We have presented the synthesis of unprecedented 9-(O)-aryl-substituted BBR through a copper-catalyzed cross coupling of tetrahydroberberrubine with aryl iodides and subsequent oxidation. The substrate scope is generally broad and various aryl groups have been introduced to the BBR

Selenophene-containing heterotriacenes by a C–Se coupling/cyclization reaction

• Pierre-Olivier Schwartz,
• Sebastian Förtsch,
• Astrid Vogt,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2019, 15, 1379–1393, doi:10.3762/bjoc.15.138

• crucial cyclization steps to the stable and soluble fused systems were achieved by copper-catalyzed C–S and C–Se coupling/cyclization reactions. Structures and packing motifs in the solid state were elucidated by single crystal X-ray analysis and XRD powder measurements. Comparison of the optoelectronic

• different scan rates (right). Synthesis of heterotriacenes DTT 1 and DTS 2 via copper-catalyzed cross-coupling reactions. Synthesis of selenolotriacenes DST 3 and DSS 4. Oxidative polymerization of heterotriacenes 1–4 to corresponding conjugated polymers P1–P4. Bond distances, bond angles, and distances D

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• –alkynylation (GA) [48] and an activation–alkynylation (AA) [49] sequence, which both take advantage of a copper-catalyzed alkynylation of the intermediary formed (hetero)arylglyoxyl chloride (Scheme 1). The alkynediones can be subsequently transformed, still in the same reaction vessel, to quinoxalines [48][50

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• -cyclopropylation reactions, a transformation which is similar to the Chan [45], Evans [46], Lam [47] arylation reaction of N–H and O–H containing substrates. These seminal reports greatly contributed to the synthesis of cyclopropylated compounds in addition to expanding the scope of copper-catalyzed reactions in

• agent of thiophenols (Scheme 2g). The publication of copper-catalyzed methods by Feng and Xu to S-arylate thiophenols [53] and by Guy to S-arylate alkyl thiols [54] gave us confidence to proceed ahead with our endeavour for which we herein report our results. Results and Discussion We began by testing

• only viable alternative to bipyridine (Table 1, entry 7), with other ligands commonly used in copper-catalyzed reactions such as proline and 2,2,6,6-tetramethyl-3,5-heptanedione giving yields under 15%. Reducing the number of equivalents of boronic acid 25 and sodium carbonate was found to be well

Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

• (aryltriazolyl)methyl galactopyranosyls 10a–n in fair to good yields (42–78% yields) via a copper-catalyzed Huisgen cycloaddition [17][32]. The resulting (aryltriazolyl)methyl galactopyranosyls 10a–n were debenzylated using palladium hydroxide on carbon in a 2:1 cyclohexene and ethanol mixture to give 1a–n in

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• -iodo-4-nitrobenzene (3) [68]. The TEMPO moiety was introduced at the benzylic position of 5a and 5b using the copper-catalyzed radical reaction in the presence of tert-butyl hydroperoxide (TBHP) to afford 2a and 2b in 38% and 52% yield, respectively [69]. The caged TEMPOs 2a and 2b were thermally

New α- and β-cyclodextrin derivatives with cinchona alkaloids used in asymmetric organocatalytic reactions

• Iveta Chena Tichá,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2019, 15, 830–839, doi:10.3762/bjoc.15.80

• to non-methylated CDs was developed. For our purposes of using the derivatives as catalysts for enantioselective reactions, we focused on α- and β-CD skeletons. Our successful approach consisted of attaching these molecules through copper-catalyzed alkyne–azide cycloaddition (CuAAC). First, the

Solid-phase synthesis of biaryl bicyclic peptides containing a 3-aryltyrosine or a 4-arylphenylalanine moiety

• Iteng Ng-Choi,
• Àngel Oliveras,
• Lidia Feliu and
• Marta Planas

Beilstein J. Org. Chem. 2019, 15, 761–768, doi:10.3762/bjoc.15.72

• -terminal groups of the peptide and their putative target. This method has been used for the macrocyclization of peptides through, for example, copper-catalyzed azide–alkyne cycloadditions [14], ring-closing olefin metathesis [13] or the formation of an aryl–aryl bond between the side chain of two aromatic