Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• advantages are (i) the universality to a wide range of monomers such as (meth)acrylates, (meth)acrylamides, dienes, vinyl ethers/esters, etc.; (ii) tolerance to unprotected functionalities in monomers and the solvent including –OH, –COOH, –SO3H, etc.; (iii) different reaction conditions, including bulk

Acetaldehyde in the Enders triple cascade reaction via acetaldehyde dimethyl acetal

• Alessandro Brusa,
• Debora Iapadre,
• Maria Edith Casacchia,
• Alessio Carioscia,
• Giuliana Giorgianni,
• Giandomenico Magagnano,
• Fabio Pesciaioli and
• Armando Carlone

Beilstein J. Org. Chem. 2023, 19, 1243–1250, doi:10.3762/bjoc.19.92

• acetaldehyde have been reported [20][21][22][23][24]. The safety and handling problems associated with acetaldehyde can be solved by synthetic equivalents that can be generated in situ through different paths. Some examples are represented by vinyl acetate [25], silyl vinyl ethers [26], ethanol, pyruvic acid

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• sufficient. The reaction tolerated (hetero)aryl and aliphatic tosyl hydrazones as radical acceptors and a variety of olefins with different electronic natures as nucleophilic partners (i.e., vinyl ethers, sulfides, and acetamides). One example of the synthesis of a quaternary center was reported by the

Synthetic reactions driven by electron-donor–acceptor (EDA) complexes

• Zhonglie Yang,
• Yutong Liu,
• Kun Cao,
• Xiaobin Zhang,
• Hezhong Jiang and
• Jiahong Li

Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67

• trifluoromethylation (Scheme 25). A variety of olefins, such as ene carbamates, styrene, aliphatic olefins, vinyl ethers, and acrylates are compatible in this approach, affording corresponding β-(trifluoromethyl)alkynes with good to excellent yield. The bifunctionalization was achieved by an EDA-complex-initiated

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• stereocontrol were obtained when 316 was reacted with electron-rich olefins, as for example, vinyl ethers [87] (Scheme 58). In 2003, Sakamoto and co-coworkers investigated the intermolecular diastereoselective photo [2 + 2] cycloaddition of axially chiral monothiosuccinimides 319 which could enantiomerize into

• (trifluoromethyl)-1,3-dithietane (363) with alkyl vinyl ethers 371 or phenyl vinyl sulfide (372b) in DMSO at 70 °C afforded the corresponding 2,2-bis(trifluoromethyl)-3-alkoxy/phenylthiothietanes 374 and 375b, respectively, with 1,3-dithiolanes 382 as byproducts [101] (Scheme 78). The reactions of 2,2,4,4-tetrakis

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

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

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

• Pierre-Antoine Nocquet,
• Aurélie Macé,
• Frédéric Legros,
• Jacques Lebreton,
• Gilles Dujardin,
• Sylvain Collet,
• Arnaud Martel,
• Bertrand Carboni and
• François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

• vinyl ethers as key step of reaction sequences developed. Keywords: 3-amino glycals; diastereoselective additions to aldehydes; pluramycins; ring-closing metathesis; vinyl ethers; Introduction Several classes of medicinally useful molecules with antibiotic and anticancer activity contain in their

• corresponding alkynyl alcohols requires the handling of toxic tin reagents [8][9]. During these last years, ring-closing metathesis (RCM) of vinyl ethers have proved to be an efficient method for the preparation of chiral glycal scaffolds [11][12][13][14][15][16][17][18] as demonstrated in some total syntheses

• vinyl ethers 15 [13][44][45][46]. We found that the best yields were obtained using Pd(TFA)2 and n-butyl vinyl ether as solvent in the presence of bathophenanthroline as ligand. In the case of Pd(OAc)2, the reaction was slower with moderate yields. The ring-closing metathesis reaction was performed with

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• cyclization, since there is precedence of accessing medium-sized ring ethyl vinyl ethers when employing TiCl3/LiAlH4/NEt3 in DME instead of TiCl4/Zn/pyridine [23]. Direct reduction of ester 14 to the aldehyde proved to be surprisingly difficult with either DIBAL-H or LiAlH4, when the alkynyl side chain was in

Stepwise radical cation Diels–Alder reaction via multiple pathways

• Ryo Shimizu,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 704–708, doi:10.3762/bjoc.14.59

• -8588, Japan 10.3762/bjoc.14.59 Abstract Herein we disclose the radical cation Diels–Alder reaction of aryl vinyl ethers by electrocatalysis, which is triggered by an oxidative SET process. The reaction clearly proceeds in a stepwise fashion, which is a rare mechanism in this class. We also found that

• Diels–Alder reaction have employed styrenes, the scope is not limited to such electron-rich dienophiles. Bauld and Yoon demonstrated that aryl vinyl ethers, enol ether equivalents, and aryl vinyl sulfides are also promising dienophiles for the reactions (Scheme 2) [17][20][21][22][23][24][25]. We have

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• olefins. For their reaction, they applied p-toluene selenosulfonate and found that especially electron-rich olefins worked well under their conditions. The difunctionalized products (β-selenosulfones) were obtained in high yields from a series of alkyl vinyl ethers. The reaction proceeds via an oxidative

Is the tungsten(IV) complex (NEt₄)₂[WO(mnt)₂] a functional analogue of acetylene hydratase?

• Matthias Schreyer and
• Lukas Hintermann

Beilstein J. Org. Chem. 2017, 13, 2332–2339, doi:10.3762/bjoc.13.230

• nucleophilic mechanism with assistance by carboxylate base. As such, the mechanism is related to Reppe's alkali-mediated addition of alcohols to acetylene that gives vinyl ethers [45]. Alkali-mediated hydration of alkynes is not known for regular alkynes, since the carbonyl reaction products are unstable to

Scope and limitations of the dual-gold-catalysed hydrophenoxylation of alkynes

• Adrián Gómez-Suárez,
• Yoshihiro Oonishi,
• Anthony R. Martin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2016, 12, 172–178, doi:10.3762/bjoc.12.19

• in unsymmetrical alkynes can help to achieve high regioselectivity in the hydrophenoxylation. Keywords: cooperative catalysis; gold catalysis; hydrophenoxylation; N-heterocyclic carbene; vinyl ethers; Introduction During the last 30 years, N-heterocyclic carbenes (NHCs) have evolved from mere

• (3ad), acetals (3ae) and naphthyls (3af) were well tolerated and the corresponding vinyl ethers were obtained in moderate to high yields (50–98%). On the contrary, the use of azide (3ag) or boronic ester (3ah) functionalities did not afford the desired products [29]. The latter case can be explained

• the alkyne Next, we sought to assess how the electron density on the alkyne affected the reaction. Therefore, both electron-rich (1b, 1e) and electron-poor (1c) alkynes were tested using phenol 2t as nucleophile. The desired vinyl ethers, 3bt, 3ct and 3et, were obtained in moderate to good yields

Computational study of productive and non-productive cycles in fluoroalkene metathesis

• Markéta Rybáčková,
• Jan Hošek,
• Ondřej Šimůnek,
• Viola Kolaříková and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

• alkenes to hydrofluoroalkenes. Moreover, just recently a successful cross metathesis of perfluoroalkenes with vinyl ethers has been published [35]. The reported computations dealing with the metathesis of fluoroalkenes are also extremely scarce. Thus, the mechanism of the cross metathesis of norbornene

• metathesis should proceed without any significant problems providing no reactive alkylideneruthenium complexes, e.g., methyleneruthenium, participates in the active catalytic cycles. Our results are in full agreement with the recently described surprisingly successful metathesis of perhaloalkenes with vinyl

• ethers [35], but contradicts the patent [34] which describes the successful synthesis of partially fluorinated alkenes from perfluorinated and non-fluorinated alkenes. Computational Details DFT calculations were performed using the Gaussian 09W program suite [43] using the resolution-of-identity approach

Aerobic addition of secondary phosphine oxides to vinyl sulfides: a shortcut to 1-hydroxy-2-(organosulfanyl)ethyl(diorganyl)phosphine oxides

• Svetlana F. Malysheva,
• Alexander V. Artem’ev,
• Nina K. Gusarova,
• Nataliya A. Belogorlova,
• Alexander I. Albanov,
• C. W. Liu and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 1985–1990, doi:10.3762/bjoc.11.214

• exclusively the anti-Markovnikov adducts (Scheme 2). On the other hand, vinyl ethers and vinyl selenides (congeners of vinyl sulfides) were found to react with phosphine oxide 1a at 80 °C for about 30 and 20 h, respectively, to deliver difficult-to-separate mixtures of organophosphorus compounds (31P NMR). To

4-Hydroxy-6-alkyl-2-pyrones as nucleophilic coupling partners in Mitsunobu reactions and oxa-Michael additions

• Michael J. Burns,
• Thomas O. Ronson,
• Richard J. K. Taylor and
• Ian J. S. Fairlamb

Beilstein J. Org. Chem. 2014, 10, 1159–1165, doi:10.3762/bjoc.10.116

• , which are found embedded in a number of natural products. Keywords: heterocycles; Mitsunobu reaction; oxa-Michael addition; 2-pyrone; vinyl ethers; Introduction The 2-pyrone motif is a prevalent structural feature of many complex natural products and biologically active compounds [1][2]. Various

• pyronyl vinyl ethers 7. Supporting Information Supporting Information File 116: Detailed experimental procedures, characterisation data for compounds 3b–e, 4a–l, 5d, 7a–i and 9 and 1H NMR spectra for novel compounds. Acknowledgements T.O.R. is funded by an EPSRC DTA PhD studentship. We are grateful to

Aza-Diels–Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

• Amitabh Jha,
• Ting-Yi Chou,
• Zainab ALJaroudi,
• Bobby D. Ellis and
• T. Stanley Cameron

Beilstein J. Org. Chem. 2014, 10, 848–857, doi:10.3762/bjoc.10.81

• isoindolo[2,1-a]quinolone derivatives involves N-acyliminium ions or appropriate electron-deficient Schiff bases and subsequent [4 + 2] inverse-demand hetero-Diels–Alder cycloadditions with alkenes [11][12][13][14][15][16][17]. Vinylic systems from isoeugenol [11], cyclopentadiene [12], enones [13], vinyl

• ethers [14] and enolic 1,3-diketo compounds [15], have been reported to react with N-acyliminium ions obtained either from 2-formylbenzoic acid and anilines [11][12] or from N-acyliminium ions prepared from N-arylphthalimides [13][14][15]. Nucleophilic substitution of N-aryl-3-hydroxyisoindolinones from

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• reactions using zirconocene species have been reported, in particular for the reductive coupling of alkenes or alkynes with other unsaturated compounds [40][41][42][43]. On the other hand, carbozirconation of alkynes via reaction of zirconacyclopentenes with alcohols, allyl ethers, homoallyl bromides, vinyl

• ethers, alkynyl halides, and chloroformates gave ethylzirconation [17], allylzirconation [18][19], cyclopropylmethylzirconation [20], vinylzirconation [21], alkynylzirconation [22], and zirconoestification [23] products of alkynes, respectively. However, to the best of our knowledge, this method failed

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• systems, presenting appropriate stereogenic substitution at the C ring system. After merging these alcohols with an undecorated A ring, the resulting allyl vinyl ethers could serve as suitable rearrangement precursors. The synthesis of 19 and 20 commenced with enone 15 [39], which was prepared from

Reaction of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithiethane with N-vinyl compounds

• Viacheslav A. Petrov and
• Will Marshall

Beilstein J. Org. Chem. 2013, 9, 2615–2619, doi:10.3762/bjoc.9.295

• hexafluorothioacetone dimer (2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithiethane (1) were shown to react with a wide variety of electron-rich olefins and dienes, producing the corresponding cycloadducts. Reported examples include the corresponding thietanes, derived from the reaction of HFTA with vinyl ethers, vinyl

• sulfides, cyclic dienes and styrenes [1][2], fluoride anion-catalyzed reactions of compound 1 with vinyl ethers [1][3][4], vinyl sulfides [3], ketene dimethylacetal [5], styrenes [6][7], cyclic dienes [8] and quadricyclane [9]. At this point, no data for the reaction of HFTA or HFTA dimer with vinylamines

• compounds 3a and 3b are connected to the isolation protocol (see Experimental). In contrast to the corresponding cycloadducts of vinyl ethers and HFTA (2,2-bis(trifluoromethyl)-4-alkoxythietanes), which are high-boiling liquids [3], thietanes 3a and 3b are solids at room temperature. The structure of

Ambient gold-catalyzed O-vinylation of cyclic 1,3-diketone: A vinyl ether synthesis

• Yumeng Xi,
• Boliang Dong and
• Xiaodong Shi

Beilstein J. Org. Chem. 2013, 9, 2537–2543, doi:10.3762/bjoc.9.288

• access to various vinyl ethers. A catalytic amount of copper triflate was identified as the significant additive in promoting this transformation. Both aromatic and aliphatic alkynes are suitable substrates with good to excellent yields. Keywords: alkyne; copper salt; diketone; gold catalysis; vinyl

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• ) to γ,δ-unsaturated nitro compounds. In the reported examples, 6-membered cyclic O-allyl nitronates were converted to 4-nitrocyclohexenes [1][2]. This rearrangement strongly resembles the classic Claisen rearrangement of allyl vinyl ethers [3][4][5][6]. The O-allyl nitronic ester rearrangement has

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

• Marcia E. Richard,
• Daniel V. Fraccica,
• Kevin J. Garcia,
• Erica J. Miller,
• Rosa M. Ciccarelli,
• Erin C. Holahan,
• Victoria L. Resh,
• Aakash Shah,
• Peter M. Findeis and
• Robert A. Stockland Jr.

Beilstein J. Org. Chem. 2013, 9, 2002–2008, doi:10.3762/bjoc.9.235

• either electron-withdrawing or electron-donating groups were efficiently added using these catalysts. No silver salts, acids, or solvents were needed for the catalysis, and either microwave or conventional heating afforded moderate to excellent yields of the vinyl ethers. Keywords: acid-free; catalysis

• various silver/potassium salts as promoters [1]. He found that moderate to excellent yields of the vinyl ethers could be obtained upon heating the reaction mixtures (dichloromethane or THF solutions) to 100 °C for 24–146 hours. Given the current interest in the synthetic community regarding the

• catalyst in the absence of solvent to 130 °C for 20 minutes generated excellent yields of the vinyl ethers. Control reactions revealed that the arylgold compound was essential to the success of the reaction as its removal lead to quantitative recovery of starting materials. The generation of the active

A Wittig-olefination–Claisen-rearrangement approach to the 3-methylquinoline-4-carbaldehyde synthesis

• Mukund G. Kulkarni,
• Mayur P. Desai,
• Deekshaputra R. Birhade,
• Yunus B. Shaikh,
• Ajit N. Dhatrak and
• Ramesh Gannimani

Beilstein J. Org. Chem. 2012, 8, 1725–1729, doi:10.3762/bjoc.8.197

• important 3-methylquinoline-4-carbaldehydes 6a–h from o-nitrobenzaldehydes 1a–h employing a Wittig-olefination–Claisen-rearrangement protocol. The Wittig reaction of o-nitrobenzaldehydes with crotyloxymethylene triphenylphosphorane afforded crotyl vinyl ethers 2a–h, which on heating under reflux in xylene

• developed in our group [28][29]. Results and Discussion Reaction of the o-nitrobenzaldehydes 1a–h with crotyloxymethylene triphenylphosphorane under optimized reaction conditions (Scheme 1) gave crotyl vinyl ethers in good yields (Table 1). The geometrical isomers of the crotyl vinyl ethers 2a–d were well

• separated on TLC, and it was possible to separate them by column chromatography. In the case of other crotyl vinyl ethers 2e–h, all attempts to separate these (E)- or (Z)-isomers were unsuccessful. Claisen rearrangement on either (E)- or (Z)-isomers 2a–d also led to a diastereomeric mixture of 4-pentenals

Combined bead polymerization and Cinchona organocatalyst immobilization by thiol–ene addition

• Kim A. Fredriksen,
• Tor E. Kristensen and
• Tore Hansen

Beilstein J. Org. Chem. 2012, 8, 1126–1133, doi:10.3762/bjoc.8.125

• combined in a single step. Vinyl ethers, allyl ethers, acrylates and methacrylates can all be effectively incorporated as part of such thiol–ene networks. The supported organocatalysts have been tried out successfully in several asymmetric transformations, but catalyst recycling so far is relatively poor