Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• experimentally determined free energy barrier of 28 kcal mol−1 for the second transborylation reaction (Scheme 3b) [60]. The seminal work from Fontaine reported that [1-(N-2,2,6,6-tetramethylpiperidinyl)-2-BH2-C6H4]2 catalysed the C–H borylation of heterocycles with HBpin [61], the first example of a catalytic

• ‒H borylation, with an initial B‒Y/B‒H transborylation activating the precatalyst [62][63][64][65]. Zhang showed that benzoic acid decomposed HBpin to BH3 in situ to catalyse the C2‒H borylation of indoles (Scheme 4b) [66][67]. Gellrich reported the bis(pentafluorophenyl)borane-catalysed dimerisation

• borylation of thiols with HBpin (Scheme 17) [79]. Through computational analysis, a mechanism was proposed whereby the ambiphilic amine-borane 73 underwent concerted addition to the thiol 74 S–H bond, to give a zwitterion 75. After loss of H2, a neutral thioborane 76 was generated, which underwent B‒S/B‒H

Dissecting Mechanochemistry III

• Lars Borchardt and
• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150

• halides as substrates in multiple reactions. For instance, within this Thematic Issue, the synthetic relevance of aryl halides was evidenced during the development of a protocol for the solid-state palladium-catalyzed borylation reported by Kubota, Ito, and co-workers (Scheme 2) [6]. Moreover, Štrbac and

• . Mechanochemical palladium-catalyzed borylation protocol of aryl halides. 1,2-Debromination of polycyclic imides, followed by in situ trapping of the dienophile by several dienes. Synthesis of g-h-PCN from sodium phosphide and trichloroheptazine mediated by mechanochemistry. Mechanochemical intra- and

Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry

• Koji Kubota,
• Emiru Baba,
• Tamae Seo,
• Tatsuo Ishiyama and
• Hajime Ito

Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86

• mill; borylation; cross-coupling; mechanochemistry; solid-state reaction; Introduction Arylboronic acid and its derivatives are indispensable reagents in modern synthetic chemistry because they have been frequently used for the preparation of many bioactive molecules, natural products, and functional

• organic materials, typically through Suzuki–Miyaura coupling [1][2][3][4][5][6][7]. The palladium-catalyzed boryl substitution of aryl halides with boron reagents, termed Miyaura–Ishiyama borylation, is an efficient method for synthesizing arylboronates with high functional group compatibility [8][9][10

• ][11][12][13][14]. To date, many palladium-based catalytic systems in solution for the borylation of aryl halides have been reported [8][9][10][11][12][13][14]. However, these solution-based reactions usually require long reaction times and significant amounts of dry and degassed organic solvents

Borylated norbornadiene derivatives: Synthesis and application in Pd-catalyzed Suzuki–Miyaura coupling reactions

• Robin Schulte and
• Heiko Ihmels

Beilstein J. Org. Chem. 2022, 18, 368–373, doi:10.3762/bjoc.18.41

• the borylation reaction (see above). Photochromism of naphthylnorbornadiene 6b The photoisomerization reaction of substrate 5b was monitored by absorption spectroscopy (Figure 1) and by 1H NMR-spectroscopic analysis (see Supporting Information File 1, Figure S51). In MeCN solution, norbornadiene 5b

Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• oxindole-based α-aminoboronates. The asymmetric synthesis of diverse α-aminoboronic acids by diastereoselective Cu(I)-catalyzed borylation of N-tert-butanesulfinyl aldimines was described by Ellman and co-workers for the first time in 2008 [15] and next further developed with a more stable Cu(II) catalyst

Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account

• Ranadeep Talukdar

Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137

• ]. The reason behind the C-2 attachment of the boron atom rather than at the C-3 position of the indole ring was explained by McGough et al. [37]. They performed a base-free catalytic I2-assisted indole C–H functionalization (electrophilic borylation) using the N-protected indole 1 and NHC·borane 4a that

• excess of the indole reactant. It is seen that in the presence of a base the C-2 deprotonation becomes very fast in 9 (for regaining aromaticity) so the boron at the initial C-3-borylated intermediate 8 (formed via SEAr) cannot migrate fast enough, leading to a C-3 borylation product 10a (unlike Pd) [38

• ][39][40]. Here the absence of the base resulted in a slow or no C-2 deprotonation of 9, which in turn forces the boron to migrate to C-2 from C-3 (8, Scheme 2b) to result in the C-2 borylation (10b). Amines Bis(indolyl)amines have recently become important as organic electroluminescent materials [41

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Total synthesis of decarboxyaltenusin

• Lucas Warmuth,
• Aaron Weiß,
• Marco Reinhardt,
• Anna Meschkov,
• Ute Schepers and
• Joachim Podlech

Beilstein J. Org. Chem. 2021, 17, 224–228, doi:10.3762/bjoc.17.22

• protection to the bis(benzyl ether) 5b using standard conditions (Scheme 2) [27]. The preparation of boronate 6b applying the conditions used for the silylated substrate 6a (vide supra) led to a mediocre 44% yield, but the utilization of a palladium-catalyzed borylation with bis(pinacolato)diboron afforded

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

• in the presence of hydrogen gas in toluene at room temperature, confirmed by mass spectral data as well as NMR spectroscopy (Scheme 20) [14]. As can be inspected from Scheme 21, the dimer 90 of sumanene (2) was obtained by two different routes, first by employing a one-pot borylation as well as a

• corresponding DA adducts 102a–d in moderate yields as shown in Table 1 [58]. o-Bromohydroxysumanene 72 was converted to o-hydroxysumanenyl borate 100 by means of a Pd-catalyzed Miyaura-borylation reaction. Compound 100 was then subjected to triflation and subsequent treatment with CsF afforded sumanyne which on

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• merging C–H activation and photocatalysis while using a single metal catalyst. In this case, an original Rh–NHC complex was used for the ortho-directed C–H borylation of phenylpyridine substrates (Figure 40) [102]. As previously, the irradiation with visible light allowed performing this challenging

• borylation under mild reaction conditions, thus delivering, after oxidation of the crude reaction mixture with Oxone, a large panel of the corresponding hydroxylated pyridine products. From the mechanistic point of view, this reaction is expected to differ from the previously described Ru-catalyzed meta

• an oxidative ortho-C–H addition step via a metal-to-ligand charge transfer process, delivering the Rh(III) hydride species. Following borylation of the Rh(III) intermediate and subsequent reductive elimination liberate the expected coupling product with concomitant regeneration of the catalytically

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• SET approach, where the first reduction of dicyanoanthracene (OD5) is achieved electrochemically, was recently disclosed by Lambert and Lin. In this report, the photoexcited radical anion of the dye was exploited for accessing aryl radicals as intermediates of a reductive borylation of aryl halides

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

•  14, a). One year later, they demonstrated that these copper-based reagents ((Phen)CuCF2RF, RF = F, CF3 and CF2CF3) were efficient in a two-step sequence reaction (borylation/perfluoroalkylation) allowing the functionalization of either sterically hindered arenes or aryl bromides with the CF2CF3 and

One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

• Ji Ma,
• Yubin Fu,
• Junzhi Liu and
• Xinliang Feng

Beilstein J. Org. Chem. 2020, 16, 791–797, doi:10.3762/bjoc.16.72

• and Discussion The synthesis of compound 1 is depicted in Scheme 2. Firstly, 2,7-bis(Bpin)pyrene (3) was prepared using an iridium-catalyzed borylation of pyrene (67% yield). Then, 2,7-diphenylpyrene (4) was obtained by Suzuki cross-coupling of 3 and bromobenzene in 77% yield. After that, the

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• reactions are discussed. Keywords: C–B bonds; copper catalysis; C–Si bonds; enantioselective reactions; sp3 carbon functionalization; Introduction Transition-metal-catalyzed silylation and borylation are useful transformations [1], widely studied because organosilicon [2][3] and organoboron compounds [4

• bond formation Organoboron compounds are widely used in C–C and C–X (X = N, O) bond constructions. Straightforward methods for their synthesis involve the copper-catalyzed addition of organoboron compounds to alkynes, alkenes, and unsaturated carbonyl compounds, as well as the nucleophilic borylation

• have been reported to take place in high yields, along with high diastereo- and enantioselectivities. Applications of optimized ligands, such as (R,R)-QuinoxP* and (R,R)-iPr-DuPhos, for borylation of (E)-allylic phosphates 334 delivers either the trans or cis-configuration of these cyclopropyl moieties

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• direct borylation of C–H bonds in terrylene in 56% yield. The product is soluble in common organic solvents and could be purified without column chromatography. Single crystal X-ray diffraction analysis revealed that the terrylene core is not disturbed by the substituents and is perfectly flat. The

• photophysical properties of TB4 are also unchanged by the substituents because the carbon atoms at 2,5,10,13-positions have less coefficients on its HOMO and LUMO, estimated by theoretical calculations. Finally, the same borylation reaction was applied for quaterrylene, resulting in the formation of soluble

• tetra-borylated quaterrylene despite a low yield. The post modification of rylenes enables us to prepare their borylated products as versatile units after creating the rylene skeletons. Keywords: borylation; π-conjugation; oligorylene; single crystal X-ray structure; solubility; Introduction Compared

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• ], and borylation [32]), has been in great demand recently rather than the conventional multistep synthesis with nucleophilic substitution/cross-coupling via halogenation of BODIPYs [33] or from the activated precursors [34] via unstable pyrrolic intermediates. In particular, halogenation (e.g

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

• initial step. In early 2019, our research group reported the copper-photocatalyzed borylation of organic halides using [Cu(I)(DMEGqu)(DPEPhos)]PF6 as the photocatalyst (Scheme 26) [41]. The photocatalytic Miyaura borylation reaction was carried out using aryl iodides bearing either electron-donating or

• amination of NHP esters. Photocatalytic decarboxylative alkynylation using [Cu(I)(dq)(binap)]BF4. Copper-photocatalyzed alkylation of glycine esters. Copper-photocatalyzed borylation of organic halides. aUnder continuous flow conditions. Copper-photocatalyzed α-functionalization of alcohols with glycine

Six-fold C–H borylation of hexa-peri-hexabenzocoronene

• Mai Nagase,
• Kenta Kato,
• Akiko Yagi,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2020, 16, 391–397, doi:10.3762/bjoc.16.37

• -catalyzed six-fold C–H borylation of HBC was successfully achieved by screening solvents. The crystal structure of hexaborylated HBC was confirmed via X-ray crystallography. Optoelectronic properties of the thus-obtained hexaborylated HBC were analyzed with the support of density functional theory

• calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups. Keywords: C–H borylation; hexa-peri-hexabenzocoronene; iridium catalyst; X-ray crystallography; Introduction Polycyclic aromatic hydrocarbons (PAHs

• functional groups [15], hexaborylated HBC is expected to be a platform for the synthesis of diverse functionalized HBCs. Herein, we report the six-fold C–H borylation of unfunctionalized HBC (Figure 1c). By screening solvents, we have established suitable reaction conditions for the synthesis of

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

• /Taniaphos-catalyzed β-borylation of an α,β-unsaturated acylimidazole, leading to various enantioenriched β-hydroxy products after oxidation (up to >98% ee) [41]. Interestingly, following the aforementioned iterative ECA strategy, the postfunctionalized chiral acylimidazole 41 derived from (S)-citronellal

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• 5 a Pd-catalyzed one-pot reaction consisting of a borylation and Suzuki coupling was applied. Thus, starting from 1-chloroanthracene (4) and using SPhos/Pd2dba3 (8:1) as the catalyst, a full conversion to the Miyaura-type borylated intermediate was achieved (TLC analysis) after 5 hours at 110 ºC

• triaryl systems 12–15 following a similar Pd-catalyzed one-pot borylation-Suzuki coupling strategy as mentioned above, using 1-chloroisoquinoline as the coupling partner (Scheme 3). The desired compounds 12–15 were obtained in 44–70% yield. The 1H NMR spectra, recorded at 25 °C, showed the coexistence of

• ). The synthesis of the borylated dyes 16–19 was carried out following a methodology that was previously reported by some of us [42] and that is based on the Ir-catalyzed nitrogen-directed ortho-borylation of arylisoquinolines [37][38]. Despite of the presence of many aromatic C–H bonds which could be

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• -coupling reactions. Herein, stereodefined 1,3-enynes, including tetrasubstituted ones, were straightforwardly synthesized from cis or trans-alkynylated oxiranes in good to excellent yields by a one-pot cascade process. The procedure relies on oxirane deprotonation, borylation and a stereospecific

• tetrasubstituted alkenes [6][7]. Capitalizing on these precedents, Aggarwal et al. showed that oxiranes could be homologated to diols through lithiation, borylation, rearrangement and oxidation of the so-formed β-hydroxyboranes [8]. More recently, Blakemore et al. applied this sequence to sulfinyloxiranes [9

• afforded a mixture of the 2 possible isomers, although in similar overall yield (Table 2, entry 2 vs 1). Decreasing the temperature from −78 to −92 °C for the deprotonation–borylation steps rewardingly allowed the exclusive formation of the E-enyne 4 as a single isomer (Table 2, entry 3). After these

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

• resulting biaryl monocyclic peptidyl resin leading to the formation of the expected biaryl bicyclic peptide. This study provides the first solid-phase synthesis of this type of bicyclic compounds being amenable to prepare a diversity of synthetic or natural biaryl bicyclic peptides. Keywords: borylation

• peptidyl resin precursor containing the required boronate and halogenated amino acid derivatives followed by its cyclization through the formation of an aryl–aryl bond between these two amino acids via a Suzuky–Miyaura reaction. It is worthwhile to mention that both the borylation and the cross-coupling

• 9-fluorenylmethoxycarbonyl (Fmoc)/tert-butyl (t-Bu) strategy (Scheme 2). The non-commercially available amino acids Boc-Phe(4-BPin)-OH, Fmoc-Phe(4-I)-OH and Fmoc-Glu-OpNB were prepared in solution. Boc-Phe(4-BPin)-OH was obtained from Boc-Phe(4-I)-OH [27] through esterification, Miyaura borylation

Synthesis and biological activity of methylated derivatives of the Pseudomonas metabolites HHQ, HQNO and PQS

• Sven Thierbach,
• Max Wienhold,
• Susanne Fetzner and
• Ulrich Hennecke

Beilstein J. Org. Chem. 2019, 15, 187–193, doi:10.3762/bjoc.15.18

• PQS such as formylation followed by oxidation failed when applied to OMe-HHQ (3). Alternatively, ortho-metalation next to the methoxy group of OMe-HHQ (3) followed by borylation/oxidation was investigated. Several trials using different lithium bases failed and only small amounts of oxidation products

Calixazulenes: azulene-based calixarene analogues – an overview and recent supramolecular complexation studies

• Paris E. Georghiou,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Hidetaka Nishimura,
• Jaehyun Lee,
• Atsushi Wakamiya and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2018, 14, 2488–2494, doi:10.3762/bjoc.14.225

• Suzuki–Miyaura coupling reaction of bromobenzene with 5,7-di(Bpin)azulene, which in turn was formed via the exhaustive borylation of azulene with excess bis(pinacolato)diboron (B2pin2) [21]. Cyclocondensation of 5,7-diphenylazulene with formaldehyde produced 5 [22] under conditions similar to those used

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• alkynyl iodoarene cyclization/borylation to form cyclized vinylboronic esters, in which transmetalation between the generated vinylcobalt and chromium salt was a critical step (Scheme 4) [16]. As part of our continuing work on the cobalt-catalyzed functionalization of carbon–carbon unsaturated bonds, a

• characters of organometallics depending on the central metals. Ni/Cr or Co/Cr-catalyzed NHK reaction. Functionalization of alkynes via carbocobaltation. Cyclization/borylation of alkynyl iodoarenes using the Co/Cr catalyst. Three-component coupling of aryl iodides, arenes, and aldehydes using Co/Cr catalyst