Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• Figure 2. The most frequently used mechanisms of converting light energy into chemical energy using photoredox catalysts are: (i) photoredox catalysis; (ii) organometallic excitation; (iii) light-induced atom transfer, and (iv) energy transfer. Basically, a photoredox catalyst transforms light energy

• disappearance of phosphorescence, following the Frank–Condon principle [44][45]. As far as the singlet and triplet excited states of organic dyes and organometallic compounds are concerned, there is a difference in lifetimes. Usually, the lifetime of excited states of organic dyes is nanoseconds, whereas for

• organometallic compound, the time frame is microseconds. In fact, it has been observed that by virtue of multiple symmetry-allowed and -forbidden electronic transitions, the exact scenario of excited states is highly complex, and thereby offering diverse multiplicities to ground and excited states [46][47][48

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

• -deficient functions (i.e., aldehydes, thioesters, acylimidazoles, N-acyloxazolidinones, N-acylpyrrolidinones, amides, N-acylpyrroles) were recently investigated. Remarkably, only a few chiral copper-based catalytic systems have successfully achieved the conjugate addition of different organometallic

• (Michael acceptors) is one of the most relevant and versatile methods to achieve this goal [1][2][3][4]. Among the plethora of metals studied, copper-based catalytic systems proved to be highly efficient for the conjugate addition of various organometallic reagents, such as diorganozinc, triorganoaluminium

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

• , agrochemicals and bioactive natural products. Generally, α-alkoxyalkyl anions are presynthesized as stoichiometric organometallic reagents such as organolithium, organozinc, organocuprate, organostannane, organosilane and organoboron compounds [1][2][3][4][5][6]. Alternatively, we showed that easily available

Efficient method for propargylation of aldehydes promoted by allenylboron compounds under microwave irradiation

• Jucleiton J. R. Freitas,
• Queila P. S. B. Freitas,
• Silvia R. C. P. Andrade,
• Juliano C. R. Freitas,
• Roberta A. Oliveira and
• Paulo H. Menezes

Beilstein J. Org. Chem. 2020, 16, 168–174, doi:10.3762/bjoc.16.19

• organometallic species of Cd [16], Ga [17], In [18], Ti [19], Al [20] and Bi [21] were described. However, the majority of these methods involve reagents that are difficult to prepare and to handle due to the sensitivity to air and moisture. The use of less reactive species based on tin [22][23][24], silicon [25

Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

• Celine Bittner,
• Dirk Bockfeld and
• Matthias Tamm

Beilstein J. Org. Chem. 2019, 15, 2534–2543, doi:10.3762/bjoc.15.246

• shown for complex I as well [13][16][46]. Beforehand, the promotion of terminal alkyne metathesis (TAM) proved to be difficult due to several deactivation pathways [47][48][49][50][51][52][53]. Regarding the metathesis of organometallic substrates, numerous examples of a conversion via olefin metathesis

• illustrated for alkyne metathesis reactions of organometallic compounds. After some stoichiometric reactions of ruthenium and rhenium half sandwich complexes [70], several reactions have been described exploiting the reactivity of acetylenic ferrocene compounds [71][72][73][74][75]. For most of 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

• fluorination methods to these building blocks, such as Friedel–Crafts-type electrophilic halogenation [10][11], Sandmeyer-type reactions of diazonium salts [12], and halogenations of preformed organometallic reagents [13], commonly involve multiple steps, harsh reaction conditions, and the use of

• review covers mainly two types of transition-metal-catalyzed reactions: 1) cross-couplings with a fluorinated organometallic species or a halogenated fluorinated species and 2) the direct introduction of fluorinated moieties into nonfunctionalized substrates with a fluorinated reagent. We hope that this

• formed from A with Selectfluor or NFSI instead of an organometallic intermediate as usual. Then, the activated Pd(IV)–F electrophile B would be capable of electrophilic fluorination of weakly nucleophilic arenes. This unusual mechanism of catalysis may provide a new idea to the catalysis of C–H

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• properties, synthetic transformations, organometallic chemistry and metal-catalysed reactions, an excellent review was recently published by Radhakrishnan and co-workers [33]. This highlight article is intended to give the reader an overview of the varied and exceptional cycloaddition chemistry of fulvenes

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• ; metathesis; potassium; Introduction Halide (or ‘salt’) metathesis is a broadly useful synthetic technique in organometallic chemistry, applicable to elements across the entire periodic table. A typical instance involves the reaction of a metal halide (M'Xn) with an organoalkali metal compound (RM; M = Li

• , which promotes reactions through grinding or milling with no, or minimal, use of solvents, has been used in conjunction with halide metathesis to form organometallic compounds of the transition metals [3][4][5][6][7] and both s- [8][9] and p-block [10][11] main group elements. The extent to which the

• between M'X and MX becomes particularly small? Here we describe the application of mechanochemistry in an organometallic context to examine alkali metal halide exchange unassisted by solvents. The organic group used is the bulky 1,3-bis(trimethylsilyl)allyl anion, [1,3-(SiMe3)2C3H3]− ([A']−) [13][14], for

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

• dimethylamino- or nitro-substituted aldehydes did not result in the target compound that might be due to the deactivation caused by coordination of these groups with the catalyst. Metal–carbene complexes attracted the attention of organic chemists and have become an important branch of organometallic chemistry

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

• Manuel Pedrón,
• Laura Legnani,
• Maria-Assunta Chiacchio,
• Pierluigi Caramella,
• Tomás Tejero and
• Pedro Merino

Beilstein J. Org. Chem. 2019, 15, 1552–1562, doi:10.3762/bjoc.15.158

• substituents effects (Scheme 2) [15]. Three years later, Waegell et al. proposed a (2 + 2) concerted mechanism [12], although the intimate nature of the organometallic intermediates was not completely elucidated [16]. After some discussion in which Bakke et al. confirmed their initial proposal [17][18] and

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 of either terminal or organometallic alkynes with vinyl halides or of alkynyl halides with vinylic organometallics [20]. However, both routes may lead to mixtures of stereoisomers and synthetic approaches to stereodefined substituted α-enynes remain scarce and thus still represent a

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

• this method, particularly with respect to medicinal chemistry where expedient methods from easily accessible substrates are needed. Organobismuth compounds are organometallic reagents that possess a C–Bi bond and which can be synthesized from inexpensive and low-toxic bismuth salts [24][25]. Due to the

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• ) across the double bond of cyclopropenes [42], a very large number of groups have reported the addition of organometallic species demonstrating the generality of this approach for the preparation of cyclopropanes [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63]. To

• organometallic species. The presence of a bulky substituent (alkyl or aryl) at the opposite face at the C3 position might equally be important as it might induce an additional steric parameter leading to a potentially more selective carbometalation reaction. The substitution pattern on the double bond needs to

• be addressed carefully as it plays an important role in the control of the regioselectivity of the reaction pathway. An alkyl group on the C1 position of the cyclopropene should control the regioselectivity of the addition of the organometallic species to give the more stable secondary

Synthesis of polydicyclopentadiene using the Cp₂TiCl₂/Et₂AlCl catalytic system and thin-layer oxidation of the polymer in air

• Zhargolma B. Bazarova,
• Ludmila S. Soroka,
• Alex A. Lyapkov,
• Мekhman S. Yusubov and
• Francis Verpoort

Beilstein J. Org. Chem. 2019, 15, 733–745, doi:10.3762/bjoc.15.69

• obtain a polymer with particular properties – polydicyclopentadiene (PDCPD) [8][9]. Cationic polymerization of DCPD takes place with metal-halide-based catalyst systems and organometallic compounds. A number of scientific reports were dedicated to the investigation of DCPD polymerization based on these

• interaction of organometallic transition metal complexes with organic aluminum compounds. The formation of such unstable bis(cyclopentadienyl)titanium dichloride complexes with a Ti=CHR fragment is possible as well in this case. The obtained complex is polarized in such a way that the metal has a positive

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• from the incorporation of a catalytically active organometallic moiety within a protein scaffold. Such biohybrid catalysts enable a chemogenetic optimization of their catalytic performances. As olefin metathesis is bioorthogonal, it offers attractive features for the manipulation of biological systems

• . Comprehensive reviews on ArMs can be found elsewhere [63][64]. Several artificial metalloenzymes able to perform metathesis, coined artificial metathases, have been reported since 2011. The artificial metathases rely on different strategies to anchor the organometallic moiety to the protein scaffold and include

• -diallyltoluenesulfonamide (21) in aqueous media, achieving encouraging results at pH 4 and in the presence of MgCl2 [65]. The chemical optimization of the organometallic moiety revealed catalyst 60, which was combined with streptavidin (Sav) to afford ArM 1 (Scheme 13). Ward and co-workers reported another artificial

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• -dihydropyridine derivatives may be also accomplished by using catalysis with organometallic complexes [72][73][74][75][76][77][78][79] or platinum nanoparticles [80]. This recently developed approach stems from an independent field of research, which focuses on the regeneration of NAD(P)H from NAD(P)+ [81][82

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• isomerized into 1-methyl-3,3-difluorocyclopropene (A”) [21] (Scheme 1, reaction 1). Another approach relies on the reaction of cyclopropenylmethyl organometallic species C with electrophiles through an SE2’ process leading to substituted alkylidenecyclopropanes D (Scheme 1, reaction 2). Examples of those

• addition of cyclopropenylmethylboronates to aldehydes was also reported [25]. A complementary strategy involves the addition of nucleophiles, in particular organometallic reagents, to cyclopropenylcarbinols or their derivatives E, which leads to alkylidenecyclopropanes F through a formal SN2’ process

Regioselective addition of Grignard reagents to N-acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ⁵-2-oxopiperazines

• Valentine R. St. Hilaire,
• William E. Hopkins,
• Yenteeo S. Miller,
• Srinivasa R. Dandepally and
• Alfred L. Williams

Beilstein J. Org. Chem. 2019, 15, 72–78, doi:10.3762/bjoc.15.8

• the nucleophilic addition of Grignard reagents to N-acylpyrazinium salts. A literature search showed this organometallic reagent reacting with pyrazine N-oxides towards the one-pot synthesis of N-Boc-protected N-hydroxy-substituted piperazines in good yields [6]. Methylmagnesium iodide was observed

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• -proline-catalyzed aldol reaction. Organocatalysis has become a major research field with many applications and has proven to be a valuable complementary approach to organometallic or enzymatic catalysis [29][30][31][32][33][34]. The advantages especially in comparison to organometallic catalysis lie in a

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• regenerates the catalyst. As it is a fast-growing field, this review will be mainly focused on an overview of the recent advances concerning the development of organic and organometallic photoredox catalysts for the photoreticulation of multifunctional monomers for a rapid and efficient access to 3D polymer

• observed for organometallic compounds for example with organic molecules as ligands. This ligand possesses σ, σ*, π, π* and n molecular orbitals [21]. When orbitals of this ligand are fully occupied, a charge transfer is possible from it to the empty or partially filled metal d-orbitals as illustrated in

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

• Rudolf Knorr and
• Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

• formally) heterolytic cleavage of C–C single bonds can provide cases of interest if it generates organometallic compounds under unusual conditions. The well-known cases of alkoxide fission [1][2][3] (top line of Scheme 1) may be viewed as a reversed formation of an alkoxide A1M1 from an organometallic C–M1

• alkoxides A1M1 and A2M1 may be obtained under thermodynamic control. (b) Trapping of the other equilibrium component (R1)2C=O by a nucleophile might accumulate the organometallic compound C–M1. (c) A1M1 may be used to replace M1 by M2 with intent to study a different organometallic C–M2 (bottom part of

• a nucleophile was not tried here but might serve to accumulate the organometallic equilibrium component for the purpose of spectroscopic characterization or X-ray diffraction analyses. (iv) Fission of the lithium alkoxide of the adduct 13 of adamantan-2-one appeared to be comparably fast on the

Olefin metathesis catalysts embedded in β-barrel proteins: creating artificial metalloproteins for olefin metathesis

• Daniel F. Sauer,
• Johannes Schiffels,
• Takashi Hayashi,
• Ulrich Schwaneberg and
• Jun Okuda

Beilstein J. Org. Chem. 2018, 14, 2861–2871, doi:10.3762/bjoc.14.265

• enzymes is quite limited. Apart from engineering natural enzymes, the approach of connecting abiotic co-factors (such as organometallic complexes) to natural or re-engineered protein scaffolds offers an attractive combination of both, broad reaction scope of chemical transformations as well as control of

• limited. Covalent anchoring of an organometallic complex offers the precise positioning of a catalyst within a protein scaffold. Formation of the covalent bond between cofactor and protein ensures an irreversible binding of the active site (i.e., the metal complex). This approach is highly versatile

• transporter and removed the cork domain that is responsible for the iron transport [58]. This generated an “empty” barrel offering sufficient space to incorporate bulky organometallic catalysts. The variant lacking the cork domain is termed FhuA Δ1-159 (amino acids from 1 to 159 are deleted compared to the

Transition metal-free oxidative and deoxygenative C–H/C–Li cross-couplings of 2H-imidazole 1-oxides with carboranyl lithium as an efficient synthetic approach to azaheterocyclic carboranes

• Lidia A. Smyshliaeva,
• Mikhail V. Varaksin,
• Pavel A. Slepukhin,
• Oleg N. Chupakhin and
• Valery N. Charushin

Beilstein J. Org. Chem. 2018, 14, 2618–2626, doi:10.3762/bjoc.14.240

• of promising heterocyclic carboranes: (i) condensation of decaborane (B10H14) with substituted acetylenes [27][28][29][30], (ii) carboryne-based cycloaddition reactions [31][32][33], and (iii) C–X/C–M cross coupling of halogenated azaheterocycles (X = Br, Cl, F) with carborane organometallic

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• methylcobalamin and adenosylcobalamin (coenzyme B12) that serve as organometallic cofactors in B12-dependent enzymes. The photolysis (thermolysis) of alkylcob(III)alamins leads to the formation of the corresponding alkyl radical and cob(II)alamin with homolytic Co(III)–C bond cleavage (Figure 1b). This high

• functions of B12 are exploited by bound apoenzymes. B12 is recycled or reactivated in vivo as observed in methyonine synthetases. Understanding the mechanisms of B12 enzyme reactions and the role of B12 is very important from the viewpoint of bioinorganic and organometallic chemistry, organic syntheses, and