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

• irreversible precipitation of a product, and an inevitable shift in dynamic equilibrium. Several types of reversible reactions have been successfully employed in the formation of DCL, including transesterification, peptide bond exchange, disulphide exchange, olefin metathesis and boronic ester formation [189

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

• of the C(8)H2 group in the COSY spectrum contain only two additional cross-peaks with the olefin signals at 5.64 and 5.86 ppm. Analysis of the 1H,13C-HSQC spectrum revealed that the latter protons are bound to carbon atoms with chemical shifts 135.3 and 131.1 ppm, respectively, and this finding

Bipolenins K–N: New sesquiterpenoids from the fungal plant pathogen Bipolaris sorokiniana

• Chin-Soon Phan,
• Hang Li,
• Simon Kessler,
• Peter S. Solomon,
• Andrew M. Piggott and
• Yit-Heng Chooi

Beilstein J. Org. Chem. 2019, 15, 2020–2028, doi:10.3762/bjoc.15.198

• ) showed 15 distinct carbon signals, while 13C and 1H NMR data (Table 1) indicated an isopropyl unit (δC 28.3, 29.2 and 73.1; δH 1.20 and 1.24), one tertiary methyl (δC 20.1; δH 1.25), a disubstituted olefin (δC 105.7 and 155.2; δH 5.12 and 4.89) and four methines (δC 39.6, 51.1, 51.6 and 54.0; δH 1.73

• which are Dothideomycetes. Significantly, this is the first report pertaining to sativene-type sesquiterpenoids from B. sorokiniana in 25 years, since the first and only literature account was published in 1994 [2]. Furthermore, structure 4 has a seco-sativene type scaffold without an olefin unit at C-1

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

• isomerization of olefin 43, the benzylic oxidation of 8, the use of m-CPBA to introduce the C-9,11 epoxide and the non-stereoselective reduction of the C-14 carbonyl group using sodium borohydride, caused an unacceptable overall yield (1.6%). This pioneering work undoubtedly established the basis for the future

• corresponding N-oxide followed by Cope elimination gave olefin 62. Cleavage of olefin 62 with OsO4 and NaIO4 afforded ketone intermediate 10, which was enolized by (iPr)2NLi (LDA) and further reacted with formaldehyde to afford hydroxy ketone 63. Protection of the hydroxy group of 63 as 2-methoxypropyl ether

• were employed to successfully achieve Berchtold’s tetracyclic C-5,C-6 olefin intermediate 45 in only 7 steps with 8.1% overall yield in a protecting-group-free synthesis. However, we know the conversion of Berchtold’s C-5,C-6 tetracyclic olefin intermediate 45 to triptophenolide methyl ether (8) is a

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• tributyltin radical with 1a. The electrophilic α-carbonyl radical A does not react with CO even at high CO pressure [6], and therefore selectively adds to electron-rich olefin 2a to form a carbon-centered radical B. The radical B, regarded as a nucleophilic radical, then undergoes radical carbonylation with

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

• hydrolysis. Installation of the allyl group at the nitrogen atom required prior derivatization as an oxazolidin-2-one and Birch reduction to furnish 204. To construct a properly functionalized piperidine ring olefin metathesis was performed to supply the key intermediate 205. Taking advantage of the steric

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• functional group tolerance to halogen, olefin and nitrile groups among others. Moreover, this multicomponent reaction is suitable for a one-pot cascade annulation providing a thioxo dihydroquinazolinone derivative in a metal-free approach. Compared to other reported syntheses of thiocarbamates, this method

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• biosensors [49][53]. Tetraphenylethylene (TPE) and its derivatives represent a classical family of AIEgens due to their simple synthesis. In TPE, four phenyl rings are linked to the central olefin through single bonds. As isolated molecule, the phenyl rings have great freedom to rotate or twist against the

• central olefin stator and thus dissipate the energy of the excited state through non-radiative relaxation pathways which makes the compound non-emissive. However, while forming aggregates, physical constraint is involved by stacking which restricts the intramolecular rotation, therefore leading to a

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

• ], chlorosulfonyl isocyanate (CSI, 1) continues to be the most reactive isocyanate to date. CSI is relatively more reactive than alkylsulfonyl isocyanate in olefin additions [2]. Its highly reactive nature is due to the polarization of the allene double bond by the highly electronegative chlorosulfonyl group. CSI

An efficient synthesis of the guaiane sesquiterpene (−)-isoguaiene by domino metathesis

• Yuzhou Wang,
• Ahmed F. Darweesh,
• Patrick Zimdars and
• Peter Metz

Beilstein J. Org. Chem. 2019, 15, 858–862, doi:10.3762/bjoc.15.83

• olefin 14 delivered aldehyde 4 with considerably higher efficiency compared to the known six-step preparation of ent-4 from (−)-menthone [21]. Asymmetric Michael addition [7][8][10] of aldehyde 4 to methyl vinyl ketone (15) proceeded with high catalyst-controlled diastereoselectivity (dr = 23:1) to yield

• ylide 21 [8] followed by alkyne generation [23] with butyllithium in a one-pot process, trienyne 3 was obtained as a 1.6:1 mixture of E and Z olefin isomers. Due to the presence of the isopropyl group at the disubstituted alkene [24] of 3, 30 mol % of the second generation Grubbs catalyst 22 were

• to 26 only proceeded with a maximum yield of 20%. Asymmetric Michael addition of aldehyde 26 to methyl vinyl ketone (15) followed immediately by treatment of the resultant unstable keto aldehyde 27 with ylide 19 delivered dibromo olefin 28 with high diastereocontrol (dr = 19:1). Olefination of ketone

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

• ; cross metathesis; Hoveyda–Grubbs catalyst; olefin metathesis; RCM; ring-closing metathesis; ring-opening cross metathesis; ROCM; ruthenium metathesis catalyst; styrene; 2-vinylbenzylamine; Introduction Ruthenium-catalysed olefin metathesis reactions have been playing an important role in various fields

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

• -terminal groups of the peptide and their putative target. This method has been used for the macrocyclization of peptides through, for example, copper-catalyzed azide–alkyne cycloadditions [14], ring-closing olefin metathesis [13] or the formation of an aryl–aryl bond between the side chain of two aromatic

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

• , which reacts with R-olefin and a Lewis base to form stable crystalline titanacyclobutanes. Both titanium carbene and titanacycles are ROMP catalysts (Scheme 4). PDCPD polymers were obtained by precipitation in ethanol, dried and characterized by FTIR, NMR, and GPC. Figure 6 displays a typical infrared

New sesquiterpenoids from the South China Sea soft corals Clavularia viridis and Lemnalia flava

• Qihao Wu,
• Yuan Gao,
• Meng-Meng Zhang,
• Li Sheng,
• Jia Li,
• Xu-Wen Li,
• Hong Wang and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2019, 15, 695–702, doi:10.3762/bjoc.15.64

• -oriented. Besides, the trisubstituted olefin (Δ3/15) was determined to be in E configuration due to the clear NOE correlations of H-15 with H3-13 and H3-14. In view of the above evidences, the relative configuration of compound 1 was determined as 1R*,2R*, the same as 1a [16][17]. Compound 2 was isolated

• two methyls at C-1 and C-2 were on the opposite side of the molecule. Besides, the NOESY correlation of one olefin proton (H-15, δH 5.93, s) and two protons at C-4 (δH 2.49, m), suggesting the Z geometry of the double bond at C-3/C-15. Finally, the sign of the [α]D values of 3 {[α]D20 −24.2 (c 0.06

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• alkyne terminus. Hydrozirconation/iodination of alkyne 17 required freshly prepared Schwartz reagent (3 equiv) and iodine (3 equiv) to obtain yields of (E)-olefin 18 above 80% with perfect stereo- and regioselectivity. For comparison, as part of a study towards kendomycin, Arimoto and co-workers had

Dirhodium(II)-catalyzed [3 + 2] cycloaddition of N-arylaminocyclopropane with alkyne derivatives

• Wentong Liu,
• Yi Kuang,
• Zhifan Wang,
• Jin Zhu and
• Yuanhua Wang

Beilstein J. Org. Chem. 2019, 15, 542–550, doi:10.3762/bjoc.15.48

• substrates. For 2-methylbut-1-en-3-yne (2i) containing both terminal alkenes and alkynes, the activity of the olefin was greater than that of the alkyne, which favors alkene cycloaddition products with a ratio of 89:11. The observed selectivity of product 4i is similar to that previously reported [11] (Table

• due to cycloaddition with an olefin group in 2j (Table 3, entry 9). When 2k was applied in the reaction, the addition product was obtained with a yield of 44% with the alkyne group being involved in the reaction (Table 3, entry 10). The reaction with 2l mainly produced 1,3-diene product 4l with a

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

• Valerio Sabatino Thomas R. Ward Department of Chemistry, University of Basel, Building 1096, Mattenstraße 24a, Biopark Rosental, 4058, Basel, Switzerland 10.3762/bjoc.15.39 Abstract Olefin metathesis is one of the most powerful C–C double-bond-forming reactions. Metathesis reactions have had a

• exploit biocompatible conditions. This review focuses on the progress made in aqueous olefin metatheses and their applications in chemical biology. Keywords: aqueous catalysis; artificial metalloenzymes; chemical biology; green chemistry; olefin metathesis; ruthenium catalysts; stapled peptides

• ; Introduction Olefin metathesis represents a versatile synthetic tool for the construction of carbon–carbon bonds [1][2][3][4][5][6][7][8][9]. Since its first report in 1956, a Ti(II)-catalyzed polymerization of norbornene [10], metathesis rapidly attracted interest among organic chemists and has been used in

Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds

• Hamada S. A. Mandour,
• Yoko Nakagawa,
• Masaya Tone,
• Hayato Inoue,
• Nansalmaa Otog,
• Ikuhide Fujisawa,
• Soda Chanthamath and
• Seiji Iwasa

Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31

• corresponding bicyclic product in excellent yield with high enantioselectivity (Scheme 1, 2p). Even the sterically demanding trisubstituted olefin-based allyl diazo Weinreb amide was found to be an effective substrate for the intramolecular cyclopropanation in this catalytic system, providing the corresponding

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

• ]. Alkylidenecyclopropanes also constitute another important class of strained carbocycles displaying a versatile chemistry owing to their multiple reactive sites (the exocyclic olefin and the proximal and distal bonds on the ring) [10][11][12][13][14][15]. Although the synthesis of alkylidenecyclopropanes can be achieved

• by many different routes, controlling the configuration of the exocyclic olefin as well as that of stereocenters on and adjacent to the three-membered ring remains a challenging task [15]. In this context, cyclopropenes can serve as useful precursors of substituted and functionalized

• alkylidenecyclopropanes. The transformation of cyclopropenes into alkylidenecyclopropanes has been achieved through different strategies (Scheme 1). The first one relies on the isomerization of the olefin in alkylcyclopropenes A from the endocyclic to the exocyclic position (Scheme 1, reaction 1) [16][17][18]. Owing to

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

• Patrycja Zak Cezary Pietraszuk Adam Mickiewicz University in Poznań, Faculty of Chemistry, Umultowska 89b, 61-614 Poznań, Poland 10.3762/bjoc.15.28 Abstract This mini-review summarizes the applications of olefin metathesis in synthesis and functionalization of polyhedral oligomeric

• POSS-substituted norbornene (or other ROMP susceptible cycloolefins) are discussed. Emphasis was put on the synthetic and catalytic aspects rather than on the properties and applications of synthesized materials. Keywords: olefin metathesis; POSS; silsesquioxanes; Introduction Silsesquioxanes are

• chemistry), POSS are often functionalized through the chemical processes of C=C bond transformation, e.g., hydrosilylation, Heck coupling, silylative coupling and olefin metathesis. Olefin metathesis, i.e., catalytic exchange of double bonds between carbon atoms, is a powerful tool in organic synthesis. The

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• groups were removed by concentrated acid. A very efficient synthesis of (2S,3S,4S)-4 starts from another serine-derived chiron, namely O-benzyl-N-Boc-D-serine [111], which was readily transformed to the Z-olefin 120 containing a benzophenone imine residue as a nitrogen protecting group (Scheme 29

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

• nanomaterials that combine various functional properties with durability and enhanced mechanical characteristics. Our mini-review addresses synthetic approaches to the design of multiblock copolymers from unsaturated monomers and polymers using olefin metathesis reactions and other ways of chemical modification

• . Keywords: ADMET; macromolecular cross metathesis; multiblock copolymers; olefin metathesis; ROMP; Introduction Nowadays, olefin metathesis has become a well-established field of organic and polymer chemistry. The discovery of metallocarbene initiators that are capable of catalyzing metathesis

• approaches to multiblock copolymer syntheses via olefin metathesis reactions developed mainly over the past ten years. The following sections address the achievements and perspectives of three main techniques used for this purpose, namely, sequential ring-opening metathesis polymerization, coupling of end

Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation

• Łukasz Gułajski,
• Andrzej Tracz,
• Katarzyna Urbaniak,
• Stefan J. Czarnocki,
• Michał Bieniek and
• Tomasz K. Olszewski

Beilstein J. Org. Chem. 2019, 15, 160–166, doi:10.3762/bjoc.15.16

• Abstract The influence of microwave and ultrasonic irradiation on the performance of ammonium-tagged Ru-based catalysts in olefin metathesis transformations in aqueous media was studied. Differences in the catalytic activity in correlation with the nature of the present counter ion and the size of the N

• -heterocyclic carbene (NHC) ligand were revealed. The presented methodology allows for preparation of a variety of polar and non-polar metathesis products under environmentally friendly conditions. Keywords: catalysis; green chemistry; microwave; N-heterocyclic carbene; olefin metathesis; ruthenium; ultrasound

• ; Introduction Olefin metathesis is well established as a powerful transformation used for effective and elegant creation of new carbon–carbon double bonds [1][2]. The development of commercially available, stable and effective catalysts for that reaction [3][4][5][6] made possible for its wide application not

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

• exquisite control of chemo-, enantio- and/or diastereoselectivity being achieved [1][2]. Previous developments have involved a large number of C=C-containing substrates but, to date, the methodology has not been yet employed with the simplest olefin, ethylene, for synthetic purposes [3]. Since diazo

• compounds bearing a carboxylate substituent are the most commonly employed carbene precursors toward olefin cyclopropanation, their use with ethylene leads to cyclopropane (Scheme 1b). De Bruin and co-workers have described [4] such product in a minor, secondary reaction (yields <12%) while studying the

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands

• Yuan-Zhen Ke,
• Shou-Ling Huang,
• Guoqiao Lai and
• Tien-Yau Luh

Beilstein J. Org. Chem. 2019, 15, 44–51, doi:10.3762/bjoc.15.4

• and the olefinic proton of unreacted norbornene pendants, respectively. In the 13C NMR spectrum, the peak at δ 139 ppm owing to the olefinic carbon of cyclobutene shifts to δ 130 ppm due to ring opening, whereas the olefin carbon of the unreacted norbornene moiety at δ 136 ppm remained unchanged after

• (Figures S8–S10). The rate constants were thus obtained (Figures S1 and S2). Strategy for sequential ROMP of 1 to yield 3. ROMP of 4 and 5 in THF at 0 °C in the presence of 10 mol % of 6. Retrosynthesis of 8 from 9. Synthesis of monomer 9. Synthesis of 14 and 8 by selective olefin metathesis