Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

• Zeguo Fang,
• Nawaf Al-Maharik,
• Peer Kirsch,
• Matthias Bremer,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

• to generate 13a and 13b as a mixture of regioisomers in a ratio of 4:1. There was no requirement to separate these isomers at this stage. Subsequent addition of potassium tert-butoxide into a mixture of 13a and 13b in dichloromethane (DCM) resulted in an efficient elimination to generate vinyl

• fluoride 14 as a major product. Vinyl fluoride 14 was purified by column chromatography in a 42% yield over the two steps. Finally, difluorocarbenene (:CF2) addition using the TMSCF3/NaI protocol was used to generate the target product 9 in 46% yield. The preparation of cyclopropyl ether 10 was

• accomplished as illustrated in Scheme 3. Reduction of cyclohexanone 15 with NaBH4 gave cyclohexanol 16 in a ratio of 2:1. The major trans product 16a was purified as a single entity by column chromatography and was isolated in 45% yield. Vinyl ether 17 could be efficiently prepared using the methodology

Towards the total synthesis of chondrochloren A: synthesis of the (Z)-enamide fragment

• Jan Geldsetzer and
• Markus Kalesse

Beilstein J. Org. Chem. 2020, 16, 670–673, doi:10.3762/bjoc.16.64

• obtained through a seven-step sequence starting from ᴅ-ribonic acid-1,4-lactone. The (Z)-vinyl bromide 4 is accessible in four steps from 4-hydroxybenzaldehyde. The pivotal cross coupling between both fragments was achieved after extensive experimentation with copper(I) iodide, K2CO3 and N,N

Asymmetric synthesis of CF₂-functionalized aziridines by combined strong Brønsted acid catalysis

• Xing-Fa Tan,
• Fa-Guang Zhang and
• Jun-An Ma

Beilstein J. Org. Chem. 2020, 16, 638–644, doi:10.3762/bjoc.16.60

• , and difluoromethyl vinyl sulfonium salts as the fluorinating partner en route to various CF2-substituted aziridines [27][28][29][30][31], and a general protocol to chiral CF2-aziridines remains an unsolved challenge. Thus, herein we report a diastereo- and enantioselective aza-Darzens reaction between

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• has allowed to perform a wide range of previously unknown synthetic transformations [19][20][21][22][23][24][25][26][27][28][29]. In these reactions, aryl(vinyl)Cu(III) species [30][31] have been proposed as key intermediates to undergo reactions with a variety of nucleophiles. Fañanás-Mastral and

• triflic acid via decomposition of ethyl triflate. As a limitation, substrates bearing a vinyl substituent or an enolizable ester group did not give any conversion. This methodology is also applicable to other dialkyl phosphonates as illustrated by the synthesis of enol phosphonates 3j, 3k and 3l

Regio- and stereoselective synthesis of new ensembles of diversely functionalized 1,3-thiaselenol-2-ylmethyl selenides by a double rearrangement reaction

• Svetlana V. Amosova,
• Andrey A. Filippov,
• Nataliya A. Makhaeva,
• Alexander I. Albanov and
• Vladimir A. Potapov

Beilstein J. Org. Chem. 2020, 16, 515–523, doi:10.3762/bjoc.16.47

• a regio- and stereoselective manner affording 1,3-thiaselenol-2-ylmethyl vinyl selenides in high yields predominantly with Z-configuration. Not a single representative of the 1,3-thiaselenol-2-ylmethyl selenide scaffold has been previously described in the literature. Keywords: 2-(bromomethyl)-1,3

• of bis(trimethylsilyl)selenide [23]. The methodology based on bis(trimethylsilyl)selenide was also successfully applied to the synthesis of functionalized asymmetric alkyl- and vinyl selenides, including cyclic disubstituted 1,3-thiaselenolane and trisubstituted thiaselenane [26][27]. Vinyl selenides

• [38][39], dithiols [38], and mercapto benzazoles [40]. These are the first examples of a nucleophilic attack at the selenium atom of the seleniranium cation 2 with the generation of a new Se–S bond, yielding new families of linear unsaturated (Z)-2-[(organylsulfanyl)selanyl]ethenyl vinyl sulfides

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

• electron-withdrawing groups in good to excellent yields. Activated aryl bromides and heteroaryl bromides were also successfully converted to the corresponding arylboronic esters in good to excellent yields. The methodology was also extended to a set of vinyl iodides, providing the vinylboronic esters in

• vinyl azide sensitization to allow the formation of the corresponding 2,5-disubstituted pyrrole (Scheme 34) [39]. The reaction was promoted by a visible-light irradiation (450 nm) using the complex [Cu(I)(dmp)(BINAP)]BF4, and the desired pyrrole was obtained in quantitative yield. Conclusion Over the

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

• the desired corresponding products were generally obtained in very good yields. The application scope of the [(bpy)CuSeCF3]2 complex was then extended to aromatic halides for the formation of C(sp2)–SeCF3 bonds. The authors demonstrated that a very broad range of (hetero)aryl halides and vinyl halides

• arylcopper(I) species was the key intermediate. Terminal alkynes were also investigated under similar reaction conditions (Scheme 13) [37]. Aromatic and π-activated aliphatic substrates led to the desired products in moderate to very good yields. Moreover, vinyl sulfone derivatives were formed when the

• )–SeCF3 bonds with [(bpy)CuSeCF3]2 developed by the group of Weng. Trifluoromethylselenolation of vinyl and (hetero)aryl halides with [(bpy)CuSeCF3]2 by the group of Weng. Trifluoromethylselenolation of terminal alkynes using [(bpy)CuSeCF3]2 by the group of You and Weng. Trifluoromethylselenolation 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

• vinyl sulfones as electrophiles (Scheme 3). Of note, both the anti- and the syn-product could be predominantly formed (with a anti:syn ratio from 83:17 to 15:85), and no diastereocontrol occurred in the absence of the organocatalyst. Interestingly, this simple protocol was successfully applied to the

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• 169 substituted with chiral auxiliaries to methyl vinyl ketone for stereoselective construction of the quaternary carbon centers in 170 (Scheme 54). While screening a number of chiral auxiliaries, the authors found that upon electrolysis under galvanostatic conditions at low temperature, the

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• -catalyzed reactions of acetylenic ketones and esters with pinacolborane have been discussed [7][8]. The Michael addition of PPh3 at acetylenic carbonyl compounds generates phosphonium/vinyl anion intermediates which have been trapped with CH-, NH-, OH- and SH-acids [5]. In this manner, the 1:1:1 reaction of

• reactions. We propose two mechanistic pathways for the synthesis of betaines 3 from N-triflylpropiolamides 1 (Scheme 6). Both of them begin with the conjugate addition of PPh3 at the C–C-triple bond, leading to the vinyl anion intermediate 5. On pathway A, 5 is protonated by the active methylene compound to

• CHXY group converts 6 into the final betaine 3. On an alternative reaction pathway (path B in Scheme 6), the initial vinyl anion 5 could be split into a 3-phosphonio-substituted propadienone 7 and the N-phenyltriflamide anion. The latter is able to deprotonate the active methylene compound, the anion

Combining the Ugi-azide multicomponent reaction and rhodium(III)-catalyzed annulation for the synthesis of tetrazole-isoquinolone/pyridone hybrids

• Gerardo M. Ojeda,
• Prabhat Ranjan,
• Pavel Fedoseev,
• Lisandra Amable,
• Upendra K. Sharma,
• Daniel G. Rivera and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 2447–2457, doi:10.3762/bjoc.15.237

• steps without purification of the intermediates. In this strategy, three different diversity sites could be generated, i.e., those derived from the isocyano and aldehyde components and a third one from the carboxylic acid used in the last acylation step. We sought to incorporate aryl or vinyl carboxylic

• acids to allow the subsequent reaction with alkynes based on the C(sp2)–H activation of these aryl or vinyl moieties. As depicted in Table 1, we chose the tetrazolic substrate 1a for the optimization of the catalytic addition of diphenylacetylene (3a), a process involving the metal-catalyzed ortho-C–H

Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• ]. Nevertheless, to the best of our knowledge, no asymmetric entry to this class of natural products has been described. Our retrosynthetic analysis of 5 is depicted in Scheme 1. The prenyl side chain would be introduced by transition metal-catalyzed cross coupling of vinyl iodide 9. Compound 9 in turn could be

• . The use of a chiral oxazaborolidine catalyst led to kinetic resolution and increased the optical purity of 17 to 95% ee. Deprotection of the diol moiety followed by Stille cross coupling with vinyl stannane 18 finally gave 5 in excellent yield (Scheme 2). Since acremine F (5) can be expected to be the

• starting material. Next, we tried to trigger the cyclization through a [2 + 2] cycloaddition followed by vinyl cyclobutane rearrangement [19][20]. We reasoned that the initially formed divinyl cyclobutane [21] should undergo an allylic rearrangement to furnish the decalin system [22][23]. Condensation

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

• trifluoromethylation reported between 2011 and 2019. Meanwhile, we also present the incorporation of difluoromethyl, trifluoromethylthiol and trifluoromethoxy groups. Some sections of this review are structured around the synthesis of alkyl-, aryl- and vinyl- as well as alkynyl organofluorides. Notably, the current

• Togni’s reagent I (11), species 10 affords the final alkyl−CF3 product and complex 13, which is used for ligand exchange with 3. C(sp2)–CF3 bond formation Palladium-catalyzed trifluoromethylation of aryl and vinyl compounds: In 2010, Watson and co-workers [121] developed the first Pd-catalyzed

• trifluoromethylation of vinyl triflates and nonaflates (Scheme 65). A variety of trifluoromethylated cyclohexenes were obtained using a catalyst system, which was composed of Pd(dba)2 or [(allyl)PdCl]2 and the monodentate biaryl phosphine ligand t-BuXPhos. Also, TMSCF3 and KF were more suitable to the

Synthesis of 1-azaspiro[4.4]nonan-1-oxyls via intramolecular 1,3-dipolar cycloaddition

• Yulia V. Khoroshunova,
• Denis A. Morozov,
• Andrey I. Taratayko,
• Polina D. Gladkikh,
• Yuri I. Glazachev and
• Igor A. Kirilyuk

Beilstein J. Org. Chem. 2019, 15, 2036–2042, doi:10.3762/bjoc.15.200

• higher temperature. According to the 1Н NMR spectra, the 8c/7c ratio never exceeded 3:1. Heating of a pure sample of 8c under similar conditions caused the emergence of signals at 5.70, 4.92, and 4.87 ppm in the 1H NMR spectra. These signals were attributed to the protons of the terminal vinyl group of

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• conversion of 89 to vinyl triflate 90, followed by reduction and palladium-catalyzed carbonylation–lactone formation to give key intermediate 8 [75][76][77]. After that, the three successive epoxides were installed by known procedures with some modification. The highlights were the introduction of the second

• enones [51]. Photoexcitation (UV, 365 nm) of [Au-Au]2+ generated [Au-Au]2+*, which could then effectively reduce the vinyl C–Br bond via a SET to generate the vinyl radical. This radical then cyclizes with an aryl group to generated a tricyclic intermediate bearing a tertiary radical. A simultaneous

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• conduction band (CB) of the metal oxide and the redox potential of the electrolyte. Abundant literature on BODIPY derivatives allowed us to identify a chemical approach to fulfill those criteria, i.e., the introduction of an electron rich unit at the 3rd and 5th positions of the BODIPY core via a vinyl

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• the major product (2R,3R,4R,1'R)-141 was separated chromatographically. To install two lacking carbon atoms the vinyl moiety was transformed into the respective aldehyde 143 (via a primary alcohol 142) which when subjected to Julia–Kocienski reaction furnished the E-olefinic terminus. Since under

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

• of biologically active imidazo[1,2-a] pyridine derivatives [108]. Encouraged by the direct synthetic strategies for imidazo[1,2-a]pyridines (IPs), Donthiri et al. have reported an efficient Cu-catalyzed C–H functionalization of pyridines with vinyl azide derivatives [109]. Their use of vinyl azide

• derivatives 29 for the synthesis of IPs was unprecedented. In this strategy, vinyl azide acts as a source of nitrogen with the liberation of N2 as a benign byproduct under aerobic and mild reaction conditions (Scheme 11). The protocol has surpassed the use of 2-AP as one of the mostly used reactants and

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• –8.07 ppm, the signal of vinyl carbon C4 at 166.8–171.9 ppm, and the signal of quaternary carbon C5 at 96.0–116.3 ppm. It is worth noting that 2,2-dichloro (A, B) and 2,2-diarylsulfanyl (F, G)-substituted cations exhibit down field shifted signals in the 31P NMR (δ 87.82–115.37 ppm) in comparison with

• determined on the basis of the observed values of the spin–spin interaction constants for vinyl protons (13–14 Hz for cis-isomers and 17–18 Hz for trans-isomers), and using H,H-NOESY correlations for Z-11a (see Supporting Information File 1). Having these conditions for hydroarylation of allene 1a in hand

• chromatography, for instance, compounds E-11m and Z-11m (Table 3, entry 9 and Supporting Information File 1). The E/Z-stereochemistry of compounds 11 was determined on the basis of the values of spin–spin interaction constants of vinyl protons, which were 13–14 Hz for Z-isomers and 17–18 Hz for E-isomers (see

Introduction of an isoxazoline unit to the β-position of porphyrin via regioselective 1,3-dipolar cycloaddition reaction

• Xiujun Liu,
• Xiang Ma and
• Yaqing Feng

Beilstein J. Org. Chem. 2019, 15, 1434–1440, doi:10.3762/bjoc.15.143

• ], but also have a broad spectrum of interesting bioactivities, e.g., anti-inflammatory [40][41]. In addition, a few porphyrin-based dipoles have been also reported [42]. Recently, a 1,3-dipolar cycloaddition reaction was performed between the vinyl group at methyl pheophorbide A and the in-situ

• derivative TPP-CH2Cl. Notably, this intermediate was labile on silica-gel column to give the precursor hydroxymethylporphyrin. Hence recrystallization was employed to purify it. Later, refluxing of the solution of TPP-CH2Cl and PPh3 in toluene gave the phosphonium salt 1 [44]. To introduce the vinyl group at

• porphyrin 2 and the corresponding nitrile oxides. Subsequently, the analysis of the 1H NMR spectra helped to establish the structure of compound 3a,b (Figure 2). In the 1H NMR spectrum of 2, the signals of the vinyl group were observed at 7.15 ppm (J = 16.0 Hz) and 7.28 ppm (J = 16.0 Hz, Figure 2, top

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 non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• acids are attached to 1,2-disubstituted α,β-unsaturated sulfones in the presence of the Rh/(S,S)-chiraphos catalytic system. Modern methods for the synthesis of functionalized sulfones, with stereocenters in the side chain, by Michael addition are based, mainly, on the use of vinyl sulfones as Michael

Remarkable effect of alkynyl substituents on the fluorescence properties of a BN-phenanthrene

• Alberto Abengózar,
• David Sucunza,
• Patricia García-García and
• Juan J. Vaquero

Beilstein J. Org. Chem. 2019, 15, 1257–1261, doi:10.3762/bjoc.15.122

• vinyl trifluoroborate. The optimal conditions to obtain 3 were found to be heating at 110 °C for 72 h. Lower temperatures and/or shorter times led to incomplete conversions in the borylative cyclization of 2. Ring-closing metathesis of 3 proceeded efficiently in the presence of 10 mol % of the second

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• protected with the 2-cyanoethyl group. These protecting groups and the linker have to be cleaved under strongly basic and nucleophilic conditions. As a result, many sensitive groups including acetal, hemiacetal, vinyl ethers, enol ethers, aldehydes, esters, activated esters, thioesters, aziridines, epoxides

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

• Victoria V. Lipson,
• Tetiana L. Pavlovska,
• Nataliya V. Svetlichnaya,
• Anna A. Poryvai,
• Nikolay Yu. Gorobets,
• Erik V. Van der Eycken,
• Irina S. Konovalova,
• Svetlana V. Shiskina,
• Alexander V. Borisov,
• Vladimir I. Musatov and
• Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

• ]. Oroidine (V) and other related vinyl 2-aminoimidazoles of this class are monomeric precursors of nagelamide A (VII), mauritiamine (VIII), sceptrin (IX), benzosceptrin A (X), axinellamines (XI) and stylissazole A (XII) alkaloids [1][4][5]. Fused 2-aminoimidazole and azepinone derivatives XIII were isolated