Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• , this latter holding the aliphatic side chain but also often having oxygenated functions [11]. Similarly, rings B and C can be naturally functionalized with a varied set of groups including hydroxy, carbonyl and olefins, which along with those present in rings A and D and the side chain are the basis of

An anomalous addition of chlorosulfonyl isocyanate to a carbonyl group: the synthesis of ((3aS,7aR,E)-2-ethyl-3-oxo-2,3,3a,4,7,7a-hexahydro-1H-isoindol-1-ylidene)sulfamoyl chloride

• Aytekin Köse,
• Aslı Ünal,
• Ertan Şahin,
• Uğur Bozkaya and
• Yunus Kara

Beilstein J. Org. Chem. 2019, 15, 931–936, doi:10.3762/bjoc.15.89

• for C10H13ClN2O3S, 276.7350; found, 277.0434. The dipolar intermediate formed in the reaction of CSI with olefins. (a) Molecular structure of racemic molecule 10 (asymmetric unit). Thermal ellipsoids are drawn at the 30% probability level. (b) Geometric parameter with H-bonded geometry. Hydrogen bonds

• are drawn as dashed lines. (c) Stacking motif with the unit cell viewed downward along the c-axis. Dashed lines indicate C–H∙∙∙O interactions. Relative energy profile of the reaction mechanism shown in Scheme 4. The reaction of CSI with olefins. The synthesis of imide 9. The synthesis of ylidene

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• across olefins [56][57]. It is worth to note in the end of this part, that we did not detect formation of chlorine-containing products (molecular peaks with the isotopic distribution characteristic for chlorine were absent in GC–MS spectra). Conclusion The present work reports an efficient method for the

Synthesis of the aglycon of scorzodihydrostilbenes B and D

• Katja Weimann and
• Manfred Braun

Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56

• transition metal-mediated, regioselective, chelation-directed activation of an aryl–hydrogen bond. A promising approach was seen in an application of Murai’s elegant ruthenium-catalyzed ortho-functionalization of aryl alkyl ketones and their addition to olefins [11][12][13][14][15]. This route appeared

• substitutions was opened based upon Murai’s ruthenium-catalyzed hydroarylation of olefins. Thus, the aglycon of scorzodihydrostilbene D became accessible in two steps from readily available starting materials. Experimental General: Melting points (uncorrected) were determined with a Büchi 540 melting point

Intramolecular cascade annulation triggered by rhodium(III)-catalyzed sequential C(sp²)–H activation and C(sp³)–H amination

• Liangliang Song,
• Guilong Tian,
• Johan Van der Eycken and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 571–576, doi:10.3762/bjoc.15.52

• components (such as olefins, alkynes) stands out for the construction of carbo(hetero)cycles from easily available starting materials [7][8][9][10]. Compared to aromatic C(sp2)–H bonds, studies on activation of vinylic C(sp2)–H bonds have been less explored, due to an intrinsic inactivity, tended to undergo

• highly substituted olefins using acrylamides. However, most of them are limited to one-step coupling or annulation and just a single ring is formed [15][16][17][18][19][20][21][22]. Therefore, it is necessary to explore a new cascade annulation of acrylamides to construct a polyfused-heteroarene skeleton

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

• ). In the ROMP of the norbornene derivative 13, ArM 6 and ArM 7 performed best, outperforming catalyst 9. A near ten-fold increase is observed for ArM 6 (Table 10, entry 2). In the cross metathesis of terminal olefins 73, 74, and 75, with the commercial catalyst 9 conversions of 79%, 98% and 94

Thiol-free chemoenzymatic synthesis of β-ketosulfides

• Adrián A. Heredia,
• Martín G. López-Vidal,
• Marcela Kurina-Sanz,
• Fabricio R. Bisogno and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2019, 15, 378–387, doi:10.3762/bjoc.15.34

• ][4], however, there are certain negative aspects of thiols that need to be taken into account (i.e., foul smell, easy oxidation into disulfide, participation as donors in one-electron events, reaction with olefins through ene-type reactions, etc) [5][6][7][8]. Hence, the development of thiol-free

Synthesis of C₃-symmetric star-shaped molecules containing α-amino acids and dipeptides via Negishi coupling as a key step

• Sambasivarao Kotha and
• Saidulu Todeti

Beilstein J. Org. Chem. 2019, 15, 371–377, doi:10.3762/bjoc.15.33

• reagents [39][40] with various halo derivatives (e.g., aryl, vinyl, benzyl, or allyl) and has a broad scope to assemble diverse targets. This reaction was first reported in 1977, and it is an elegant and versatile method that allows the preparation of biaryls and olefins in good yields. To the best of our

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• silsesquioxanes (POSS) and POSS-containing polymeric materials. Three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis polymerization (ROMP) of

• reactivity is the inactivity of vinylsilsesquioxane in homometathesis. The limitations apply to silanes containing a double bond located directly at the silyl group and do not apply to allylsilanes and other alkenylsilanes, which behave like terminal olefins and readily undergo metathesis. Application of

• metathesis in chemistry of unsaturated derivatives of POSS is limited to three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• derivatives has drawn great attention in the past several decades. In this review, recent efforts in the development of oxidative radical ring-opening/cyclization of cyclopropane derivatives, including methylenecyclopropanes, cyclopropyl olefins and cyclopropanols, are described. We hope this review will be

• skeletons and their easy availability [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The cyclopropane derivatives, especially methylenecyclopropanes [17][18][19][20][21], cyclopropyl olefins [22] and cyclopropanols [23][24] undergo ring-opening/cyclization reactions to provide a huge number of

• methylenecyclopropanes (compounds A). The cyclopropyl-substituted carbon radical D easily goes through a ring-opening to generate the alkyl radical E, and then cyclizes with the phenyl ring to afford the terminal product F (path I). The cyclopropyl olefins (compounds B) also react in the same cyclopropyl-substituted

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• metathesis reactions on polymers were mostly studied with regard to the intramolecular polymer–catalyst interactions [77][78][79] or intermolecular degradation of polymers via the cometathesis with different olefins [77][80][81]. Only recently, the cross metathesis between macromolecules, or macromolecular

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• transfer; cyclopropane; cyclopropylcarboxylate; ethylene cyclopropanation; ethyl diazoacetate; gold catalysis; Introduction Nowadays the olefin cyclopropanation through metal-catalyzed carbene transfer starting from diazo compounds to give olefins constitutes a well-developed tool (Scheme 1a), with an

• formation of electrophilic metal–carbene intermediates LnM=CRR’ [1][2] that further react with nucleophiles such as olefins en route to cyclopropanes. However, these intermediates can also react with another molecule of the diazo reagent promoting the formation of olefins RR’C=CRR’ [17]. This side reaction

• . The complex TpMsCu(thf), previously described as an excellent catalyst for olefin cyclopropanation [18], led to negative results, since only the olefins 2 (mixtures of diethyl fumarate and maleate) were detected at the end of the reaction. The second copper-based catalyst tested Tp(CF3)2,BrCu(thf) [19

N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

• Fabienne Speck,
• David Rombach and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5

• -phenylphenothiazine derivatives 1–11 as photoredox catalysts. Three of them were identified to be highly suitable for the addition of methanol to alkenes affording the corresponding Markovnikov products. Results and Discussion Activated aromatic olefins, such as 1,1-diphenylethylene (12), have reduction potentials

• Ered(S/S−·) in the range of −2.2 to −2.3 V [23][24], α- and β-methylstyrene (13a and 13b) have an Ered(S/S−·) of −2.5 to −2.7 V [25], and styrene (14) an Ered(S/S−·) of −2.6 V (Figure 1) [25][26]. For non-aromatic, alkylated olefins, like 1-methylcyclohex-1-ene (15), the reduction potentials are

• -diphenylethylene (12), but not yet α-methylstyrene (13), and clearly not non-aromatic (alkylated) olefins, such as methylated cyclohexene 15, as basic structures. The absorption of N-phenylphenothiazine (1) disappears at around 390 nm. This feature requires the excitation of the molecule using UV light sources and

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• , as increasing steric bulkiness of the NHC ligand leads to greater selectivity and improves stability. Catalyst 68 gave the highest selectivity (95%) toward terminal olefins observed until then for NHC–Ru complexes (Table 2, entry 7), but with 46% yield at 500 ppm of catalyst loading. The chiral

• (Scheme 11). More recently, Olivier-Bourbigou and Mauduit demonstrated the ability of unsymmetrical N-cycloalkyl Ru–indenylidene catalysts for the selective self metathesis of linear α-olefins to longer internal linear olefins in the absence of additives to prevent isomerization [35]. Catalyst 91 with a

• the selective metathesis of linear α-olefins and was successfully applied to selectively re-equilibrate the naphtha fraction (C5–C8) of a Fischer–Tropsch feed derived from biomass to higher value added olefins (C9–C14) that can serve as plasticizer and detergent precursors. An excellent olefin

Cross metathesis-mediated synthesis of hydroxamic acid derivatives

• Shital Kumar Chattopadhyay,
• Subhankar Ghosh and
• Suman Sil

Beilstein J. Org. Chem. 2018, 14, 3070–3075, doi:10.3762/bjoc.14.285

• the preparation of functionalized alkenes and derivatives thereof. Intricacies regarding the electronic nature of olefins, their substitution patterns and steric demands are more or less settled through the works of many workers in many reports [4][5][6][7]. Yet, a number of new reports describing the

• derivatives, belonging to class-I olefins according to Grubbs’ generalizations [31], are indeed known to be a sluggish partner in CM reactions, with homodimerization to stilbene being a recurring problem. Alkenes 4h–j containing a benzyl ester functionality at two, three and four carbons apart, respectively

Degenerative xanthate transfer to olefins under visible-light photocatalysis

• Atsushi Kaga,
• Xiangyang Wu,
• Joel Yi Jie Lim,
• Hirohito Hayashi,
• Yunpeng Lu,
• Edwin K. L. Yeow and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2018, 14, 3047–3058, doi:10.3762/bjoc.14.283

• degenerative transfer of xanthates to olefins is enabled by the iridium-based photocatalyst [Ir{dF(CF3)ppy}2(dtbbpy)](PF6) under blue LED light irradiation. Detailed mechanistic investigations through kinetics and photophysical studies revealed that the process operates under a radical chain mechanism, which

• is initiated through triplet-sensitization of xanthates by the long-lived triplet state of the iridium-based photocatalyst. Keywords: energy transfer; olefin; photocatalysis; radical; xanthate; Introduction A degenerative radical transfer of xanthates to olefins has been developed as a robust

• functionalities [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. This concept has also been of particular importance in the field of polymer science, known as reversible addition–fragmentation chain transfer (RAFT) polymerization [15][16]. Mechanistically, the degenerative transfer of xanthates 1 to olefins 2

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

• regioselective hydroformylation of aromatic olefins [84]. Interestingly, if transition metals can initiate an ionic hydroformylation reaction of aryl olefins, a free radical pathway could be promoted by use of diethoxyacetic acid and 4CzIPN, inducing the in situ generation of an equivalent of a formyl radical

• -opening metathesis polymerization. This polymerization is based on cyclic olefins whose ring strain is released during polymerization. This reaction needs a catalyst to occur [108]. Metal-free photoredox catalysts for ROMP were proposed in [109]. For example, pyrylium and acridinium salts can be used as

A tutorial review of stereoretentive olefin metathesis based on ruthenium dithiolate catalysts

• Daniel S. Müller,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2018, 14, 2999–3010, doi:10.3762/bjoc.14.279

• alkenes require high catalyst loading (see next section for details). 5 Catalyst stability Hoveyda proposed that the catalyst degradation in the presence of terminal olefins is due to the generation of unstable methylidene-ruthenium species (Scheme 4) [4]. Terminal olefins inevitably produce ethylene

• [21]. The trick is to transform in situ the terminal olefins A and B into methylene capped olefins C and D by applying a large excess of (Z)-2-butene (Z-25, Scheme 5). (Z)-2-butene (Z-25) and propene E are then removed in vacuo (100 Torr) and a new portion of catalyst is added for the cross metathesis

• reactions a 1:3 ratio of A/B was applied. Practical limitations are that A and B have to be of significantly different polarity for easy column chromatographic separation and that sterically hindered olefins are not tolerated. For some alkenes, e.g., styrenes, the homodimerization is too fast leading to

MoO₃ on zeolites MCM-22, MCM-56 and 2D-MFI as catalysts for 1-octene metathesis

• Hynek Balcar,
• Martin Kubů,
• Naděžda Žilková and
• Mariya Shamzhy

Beilstein J. Org. Chem. 2018, 14, 2931–2939, doi:10.3762/bjoc.14.272

• metathesis catalysts [1]. Albeit typical ill-defined catalysts they are still popular as relatively cheap catalysts finding industrial applications especially in the treatment of low olefins [2][3][4][5]. Their catalytic activity depends on many factors, especially on Mo loading, support acidity, and pre

• carbenes as real catalytically active species has been suggested [6][7]. The replacement of ordinary silicas for mesoporous molecular sieves SBA-15 or MCM-41 increased the catalyst activity substantially, which allowed performing the metathesis of long chain olefins under mild reaction conditions [8][9][10

• solutions were used for the metathesis of low olefins (ethylene, propylene, butenes) [11][12][13]. In the case of bulkier substrates they suffer, however, of micropore size limitations. To overcome these limitations a decrease in crystal size and the application of two-dimensional zeolites can be used [14

The influence of the cationic carbenes on the initiation kinetics of ruthenium-based metathesis catalysts; a DFT study

• Magdalena Jawiczuk,
• Angelika Janaszkiewicz and
• Bartosz Trzaskowski

Beilstein J. Org. Chem. 2018, 14, 2872–2880, doi:10.3762/bjoc.14.266

• most feasible for medium and large-sized olefins (Scheme 5) [61][62]. Results presented in Table 4 suggest that the incorporation of cationic NHC increases the Gibbs free energy (∆G10) barriers by ca. 4–6 kcal/mol with respect to the standard Hoveyda–Grubbs catalyst (Hov) [63]. Given the accuracy of

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

• ), which exhibited an improved activity of TON(per cell) ≈ 500,000 compared to Sav_WT [47]. This is the first example of a whole-cell metathesis biohybrid catalyst, opening up new possibilities to utilize olefins in biological systems in the context of artificial metabolism [14]. Nitrobindin Nitrobindin

• [52][53], and hydrogen evolution [54]. Further, Lewis et al. employed the NB scaffold for epoxidation of styrene and other olefins [55]. In all studies, the catalyst incorporated into the NB scaffold showed increased activity as compared to the protein-free catalyst under similar conditions

Synthesis of a tyrosinase inhibitor by consecutive ethenolysis and cross-metathesis of crude cashew nutshell liquid

• Jacqueline Pollini,
• Valentina Bragoni and
• Lukas J. Gooßen

Beilstein J. Org. Chem. 2018, 14, 2737–2744, doi:10.3762/bjoc.14.252

• Supporting Information File 1). In principle, these internal olefins can still undergo metathesis albeit with less activity, depending on the catalyst. It was possible to reduce the time of the reaction to 6 h with almost the same yield (Table 1, entry 11). We investigated various ruthenium catalysts in

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

• (III) form of 1 has recently been found to catalyze atom transfer radical addition of alkyl halides to olefins (phenyl vinyl sulfone and acrylates) in the presence of NaBH4 [115]. In addition, a new light-driven method for generating acyl radicals from 2-S-pyridyl thioesters was developed through the

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• ] catalyst to obtain the cross-coupling products 88a–g (81–96%). Finally, exposure of olefins 88a–g to G-II catalyst 2 in CH2Cl2 led to the formation of the respective trans-stilbene derivatives 89–95 in high yields (Scheme 14). It is worth mentioning that the loading of only 0.0001 mol % catalyst can effect

Catalyst-free synthesis of 4-acyl-NH-1,2,3-triazoles by water-mediated cycloaddition reactions of enaminones and tosyl azide

• Lu Yang,
• Yuwei Wu,
• Yiming Yang,
• Chengping Wen and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2018, 14, 2348–2353, doi:10.3762/bjoc.14.210

• cycloaddition of azides with activated dipolarophiles such as strained cyclic alkynes, enamines, enolates, electron-deficient olefins, ylides, iminium cations and alkyne anions, etc., have been identified as reliable approaches to access 1,2,3-triazole scaffolds with multiple substitution patterns [39][40][41