A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

• efficient method for C–H functionalization. The continuous flow setup allows for precise control over reaction conditions, enhanced mass transfer, and improved reaction kinetics, leading to higher efficiency and faster reaction times. In 2023, the Chiang group reported the photoelectrochemical homo-coupling

Rhodium-catalyzed homo-coupling reaction of aryl Grignard reagents and its application for the synthesis of an integrin inhibitor

• Kazuyuki Sato,
• Satoki Teranishi,
• Atsushi Sakaue,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai,
• Hiroyuki Takeda,
• Tatsuo Kinashi and
• Masaaki Omote

Beilstein J. Org. Chem. 2024, 20, 1341–1347, doi:10.3762/bjoc.20.118

• 10.3762/bjoc.20.118 Abstract A novel Rh-catalyzed one-pot homo-coupling reaction of aryl Grignard reagents was achieved. The reaction with bromobenzenes having an electron-donating group or a halogen substituent gave the corresponding homo-coupling products in good yields, although the reaction using

• heterocyclic or aliphatic bromides scarcely proceeded. A Rh(III)–bis(aryl) complex, which might be formed from RhCl(PPh3)3 and the aryl Grignard reagents, plays an important role in giving the homo-coupling products in this reaction. Furthermore, we applied the reaction to the synthesis of a novel inhibitor

• for integrins which is critical for several diseases. Keywords: biphenyltetracarboxylic acid; homo-coupling; integrin inhibitor; rhodium catalyst; Ullmann-type reaction; Introduction The Ullmann reaction is a coupling reaction of aryl halides using copper, traditionally using metallic copper-bronze

Synthesis of 3,4,5-trisubstituted isoxazoles in water via a [3 + 2]-cycloaddition of nitrile oxides and 1,3-diketones, β-ketoesters, or β-ketoamides

• Md Imran Hossain,
• Md Imdadul H. Khan,
• Seong Jong Kim and
• Hoang V. Le

Beilstein J. Org. Chem. 2022, 18, 446–458, doi:10.3762/bjoc.18.47

• expected 3,4,5-trisubstituted isoxazole 3a and 55% of a compound that we identified as furoxan 4 (a 1,2,5-oxadiazole 2-oxide) which formed through homo-coupling of substrate 1a (Table 1, entry 3). Na2CO3 in 98% water, 2% methanol produced 52% of the isoxazole 3a and 33% of compound 4 after 3 hours (Table 1

Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction

• Irina Kuznetcova,
• Felix Bacher,
• Daniel Vegh,
• Hsiang-Yu Chuang and
• Vladimir B. Arion

Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15

• labile CH2 protons. This afforded the iodinated compound 23 in 80% yield. However, Ullmann cross-coupling with o-bromo-nitrobenzene gave only trace amounts of the desired product, which we could not separate by chromatographic methods from the major homo-coupling species 24 of this reaction (Scheme 7

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• element. Moreover, it is found iron is less expensive by several magnitudes compared to other late TM catalysts (Figure 1) [35]. Although the first Fe-catalyzed homo-coupling of aryl Grignard species was reported in 1941 by Kharasch and Fields [36], it wasn’t until 1971 Kochi and Tamura demonstrated the

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• Suzuki–Miyaura cross-coupling reaction of bromosumanene 82 under microwave reaction conditions. Whereas another route involves the Ni-catalyzed aryl–aryl homo-coupling between the two molecules of iodosumanene 79 [51][52]. Moreover, the bissumanenyl 92, which is thought to be chiral because of the two

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• heterogeneous photocatalysts. A Sn porphyrin-based porous aromatic framework (SnPor@PAF) with a broad and strong optical absorption in the visible light region was used for this transformation [98]. Luo, Ji and co-workers synthesized this material by a Yamamoto homo coupling reaction using a well-designed

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• , samples of m,p’- (13), o,p’- (15), o,m’- (16), and o,o’-quaterphenyl (17) were synthesized as shown in Scheme 3. Suzuki–Miyaura coupling was used to synthesize 13, 15, and 16 from the corresponding aryl bromides and boronic acids [35]. o,o’-Quaterphenyl (17) was synthesized by homo-coupling of 2

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• Information File 1). Homo-coupling of (S)-b with Ni(COD)2 was achieved with very high diastereoselectivity and only a single atropisomer was formed. The X-ray crystal structure showed that it is (M)-(S,S)-3 (Figure 1). This high atropstereoselectivity is believed to be due to the energetically unfavorable

• removing the chiral-resolving menthyl substituent with lithium aluminium hydride (LAH), the enantioselectivity of (R)-d was higher than 99% ee when checked with HPLC (Supporting Information File 1, Figure S3). Catalyst 4 was then obtained by homo-coupling of (R)-d with Ni(PPh3)3Br2/Zn with 37% yield. The

• (Supporting Information File 1, Figure S4). The optically pure (S)-g was then obtained by removing the chiral camphanic substituent (Supporting Information File 1, Figure S5) and (S)-g was then utilized for homo-coupling with Ni(COD)2 to give catalyst 6. X-ray crystal structure of 6 showed that it is an (P

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• unstable [Pd(allyl)Cl]2 intermediate from air. Micelles were also used to perform cross-coupling between benzyl and aryl halides in water [65]. This reaction is known to result in very limited yields due to the undesired homo-coupling reaction between electron-rich and electron-poor benzyl bromides [69

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• systems [69] such as solar cell materials as well as photocatalysts for organic reactions. A phthalocyanine dimer in which TFEO-Pcs are directly linked by C–C bonds has been reported (Scheme 4) [70][71]. This homodimer was synthesized by a palladium-catalyzed homo-coupling reaction of two A3B type

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

• diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21–50% yield with ratios of diastereomers being 1.17:2.00:0.81 to 7.03:2.00. The stereochemistry of the new stereogenic centers was confirmed by X-ray structure analysis and 13C NMR data

• . Keywords: anodic decarboxylation; diastereoselectivity; Kolbe electrolysis; radical hetero-coupling; radical homo-coupling; Introduction Intermolecular radical additions with high diastereoselectivity have been described for a number of cases [1][2][3][4][5][6][7][8][9]. There are much fewer reports on

• reason, we were interested in exploring the structural influence of chiral auxiliaries (Figure 1) and the carboxylic acid on the diastereoselectivity in the anodic coupling of carboxylic acids. We report here on the diastereoselectivity found in the anodic hetero- and homo-coupling of menthol- (1)-, 8

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• oxidation peak of the TTF and the oxidation of the sexithiophene backbone. A series of hybrid electroactive compounds 54 (n = 0–2) with two oligothiophenes directly fused to one TTF unit was recently reported [92][93]. Here, triethylphosphite mediated homo-coupling of the corresponding oligothiophenes 55 (n

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

• carboxylic acids generate neutral C-centered radicals and therefore offer the opportunity to reap the benefits of clean SCPC methodology in homo-coupling processes. We found that homo-dimers 39 were indeed formed from UVA photolyses of carboxylic acids in MeCN containing dispersions of P25 [54][64]. The most

Thiazole-induced rigidification in substituted dithieno-tetrathiafulvalene: the effect of planarisation on charge transport properties

• Rupert G. D. Taylor,
• Joseph Cameron,
• Iain A. Wright,
• Neil Thomson,
• Olena Avramchenko,
• Alexander L. Kanibolotsky,
• Anto R. Inigo,
• Tell Tuttle and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1148–1154, doi:10.3762/bjoc.11.129

• the synthesis of a half-unit and a final triethyl phosphite mediated homo-coupling. The resultant compounds, 1 and 2, were fully characterised and their optical and electrochemical properties elucidated via UV–vis spectroscopy and cyclic voltammetry, and explained in conjunction with DFT level

New tris- and pentakis-fused donors containing extended tetrathiafulvalenes: New positive electrode materials for rechargeable batteries

• Shintaro Iwamoto,
• Yuu Inatomi,
• Daisuke Ogi,
• Satoshi Shibayama,
• Yukiko Murakami,
• Minami Kato,
• Kazuyuki Takahashi,
• Kazuyoshi Tanaka,
• Nobuhiko Hojo and
• Yohji Misaki

Beilstein J. Org. Chem. 2015, 11, 1136–1147, doi:10.3762/bjoc.11.128

• ethoxyphosphoryl groups (12) in 63% yield. We adopted the cross-coupling reaction between the 1,3-dithiole-2-thione and the 1,3-dithiol-2-one derivatives for the following reasons. The homo-coupling reaction of 10 afforded 12 in low yields, and purification by column chromatography was difficult because of

• undesired byproducts. The homo-coupling reaction using 11 might give 12 in a good yield, however, toxic and expensive mercury(II) acetate has to be used for the synthesis of 11. Thus, the cross-coupling reaction is useful for saving 11. The Horner–Wadsworth–Emmons reaction of 12 with 2 equiv of aldehydes

TTFs nonsymmetrically fused with alkylthiophenic moieties

• Rafaela A. L. Silva,
• Bruno J. C. Vieira,
• Marta M. Andrade,
• Isabel C. Santos,
• Sandra Rabaça,
• Dulce Belo and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 628–637, doi:10.3762/bjoc.11.71

• compounds 1 and 2 through the coupling reactions depicted in Scheme 2 also resulted in several byproducts, mainly from homo-coupling reactions. Reaction time, temperature, and amount of solvent were crucial factors for the final yields and for product purity. By optimizing these reaction parameters an

Weakly nucleophilic potassium aryltrifluoroborates in palladium-catalyzed Suzuki–Miyaura reactions: relative reactivity of K[4-RC₆F₄BF₃] and the role of silver-assistance in acceleration of transmetallation

• Vadim V. Bardin,
• Anton Yu. Shabalin and
• Nicolay Yu. Adonin

Beilstein J. Org. Chem. 2015, 11, 608–616, doi:10.3762/bjoc.11.68

• ) compounds under identical conditions (Scheme 6) (Table 4). The presented data demonstrate clearly that AgNO3, Ag2SO4, Ag[BF4], and AgF salts are less appropriate promotors for the palladium catalyzed cross-coupling than Ag2O. The significant contribution of the side reactions (hydrodeboration and homo

• -coupling) results in decreasing yields of 10a and hinders isolation of the desired product (see Table 4). Discussion The general concept of the Pd-catalyzed Suzuki–Miyaura (SM) reaction applied to the cross-coupling of K[4-RC6F4BF3] with ArX is presented in Scheme 7. The first step is the generation of

Synthesis of antibacterial 1,3-diyne-linked peptoids from an Ugi-4CR/Glaser coupling approach

• Martin C. N. Brauer,
• Ricardo A. W. Neves Filho,
• Bernhard Westermann,
• Ramona Heinke and
• Ludger A. Wessjohann

Beilstein J. Org. Chem. 2015, 11, 25–30, doi:10.3762/bjoc.11.4

• heterocyclic and natural product inspired compounds [28][29][30][31][32]. Although several protocols of U-4CR followed by transition metal-catalysed reactions have been published so far [33], to the best of our knowledge, there are no reports about U-4CR/Glaser-type (homo) coupling combinations. In view of an

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• was transformed into benzyl ester 39 in 97% yield (Scheme 6). Subsequent treatment with commercially available 1-octene and Grubbs 2nd generation catalyst [41] afforded lipidated (2S,3S)-3-hydroxyleucine derivative 40 in 63% yield without any observed homo-coupling of the amino acid. Amino acid 40 was

Towards allosteric receptors – synthesis of β-cyclodextrin-functionalised 2,2’-bipyridines and their metal complexes

• Christopher Kremer,
• Gregor Schnakenburg and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 814–824, doi:10.3762/bjoc.10.77

• were prepared starting from commercially available 4-amino-2-chloropyridine (4) and 2-amino-6-bromopyridine (5), respectively. After protection of the amino functions as 2,5-dimethylpyrroles, pyridines 6 and 7 were transformed into the corresponding 2,2’-bipyridines 8 and 9 via a nickel-catalysed homo

• -coupling reaction in excellent yields [26]. The non-symmetric 4,6’-disubstituted bipyridine 10 was obtained in good yield from a Negishi cross-coupling of 6 and 7 [27]. Cleavage of the pyrrole protecting groups of 8–10 with hydroxylamine provided the corresponding diamines 11–13 [26] in satisfying to

Camera-enabled techniques for organic synthesis

• Steven V. Ley,
• Richard J. Ingham,
• Matthew O’Brien and
• Duncan L. Browne

Beilstein J. Org. Chem. 2013, 9, 1051–1072, doi:10.3762/bjoc.9.118

• preparative synthetic chemistry. Ozone was used to oxidatively cleave a variety of alkenes whereas oxygen was used to aid the oxidative homo-coupling of terminal alkynes (Figure 19). Our use of camera imagery became more sophisticated as we began to acquire data on the precise concentrations of the gases in

Total synthesis and biological evaluation of fluorinated cryptophycins

• Christine Weiß,
• Tobias Bogner,
• Benedikt Sammet and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 2060–2066, doi:10.3762/bjoc.8.231

• ). In order to bring about complete metathesis of 16, the acrylamide 17 had to be employed in 1.2-fold excess, which resulted in a contamination of the cross-metathesis product 18 with minor amounts of the homo-coupling product 23. The latter could not be separated by flash chromatography on this stage

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• reoxidized with the Ag(I) and Cu(II) salts. Intermolecular reactions involving arenes The formation of homo-coupling products is one of the most common drawbacks in intermolecular reactions between arenes without preactivation of the substrates. In 2006, Lu and co-workers reported one of the first articles

N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters

• Takuya Uno,
• Yusuke Kobayashi and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2012, 8, 1499–1504, doi:10.3762/bjoc.8.169

• available precatalyst 3a (Figure 2) and K2CO3. Gratifyingly, when ethyl N-PMP-2-iminoacetate (4) was used as acyl anion acceptor [44], the reaction proceeded smoothly in THF at room temperature to generate the desired product 5a in 58% yield (Table 1, entry 1). Surprisingly, no benzoin 6 arising from homo

• -coupling of 1a was obtained. Encouraged by this result, we then attempted the other precatalysts 3b–e depicted in Figure 2. Imidazolium salt 3b and simple triazolium salt 3c gave no coupled product 5a (Table 1, entries 2 and 3). Further screening revealed that bicyclic triazolium salt 3d could catalyze the