Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• , catalytically generated from 1, to α-substituted acrylates 2 followed by enantioselective protonation of the resulting lithium enolate (Scheme 1) [14]. The ortho-trimethylsilyl substituent on the phenyl ring was necessary for achieving high levels of enantioselectivity. All of the reactions proceeded in high

• (Scheme 2) [15][16][17]. A Mg-(bis)oxazoline complex serves as both a Lewis acid for the activation of α-substituted acrylates 6 towards radical addition and as a chiral template for an enantioselective hydrogen atom transfer from Bu3SnH to the α-ester radical intermediate. The authors found that the

• source in the stereodetermining step [27]. In 2012, Glorius and co-workers also reported the addition of aromatic aldehydes to α-carbon substituted acrylates 33 to provide differentiated 1,4-dicarbonyls 34b with good enantioselectivity [26]. When optimizing the catalyst‘s structure, the authors found

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• arylureas at room temperature. A commercially available catalyst [Pd(MeCN)4](BF4)2 or a nitrile-free cationic palladium(II) complex generated in situ from the reaction of Pd(OAc)2 and HBF4, effectively catalyzes C–H activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates

• expanded the substrate scope to include reactions with 3-alkyl-substituted ureas, as well as a wider variety of acrylates and even some acrylamides (Figure 4, 5d–h, conditions B). Many combinations of acrylates and more challenging arylureas, however, did not produce the desired product in satisfactory

• product was obtained exclusively. Under optimized conditions, various acrylates and amides can be synthesized via C–H activation reactions (Figure 6). Methyl acrylate, which did not show good general reactivity with arylureas under previous conditions, could be coupled in excellent yields (5i, 5j, 5k). As

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• maleimides, affording the corresponding products in excellent yields (up to 98% yield) and with excellent enantioselectivity (up to 94% ee, Scheme 37) [54]. Additionally, other activated alkenes such as methyl and ethyl acrylates and acrolein reacted smoothly with 7-azaisatins, giving the corresponding

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• ’-Silyloxyenones as acceptors. As in the case of imidazolones, thiazolones also exhibit very poor reactivity in the Michael addition to methyl and tert-butyl acrylates. This problem could be circumvented by using α’-silyloxyenones as acrylate surrogates [73]. After catalyst screening and optimization of the

Application of 7-azaisatins in enantioselective Morita–Baylis–Hillman reaction

• Qing He,
• Gu Zhan,
• Wei Du and
• Ying-Chun Chen

Beilstein J. Org. Chem. 2016, 12, 309–313, doi:10.3762/bjoc.12.33

• allows a convenient approach to access multifunctional 3-hydroxy-7-aza-2-oxindoles with high enantiopurity (up to 94% ee). Other types of activated alkenes, such as acrylates and acrolein, could also be efficiently utilized. Keywords: 7-azaisatins; β-isocupreidine; bifunctional catalysis; maleimide; MBH

• acrolein catalyzed by β-isocupreidine (β-ICD) was reported by the Zhou group [5], isatin derivatives, as highly activated electrophiles, have been utilized by other groups for similar transformations with acrylates or acrylamides, affording the 3-hydroxyoxindole derivatives with moderate to excellent

• (Table 2, entries 13–15). To further assess the high electrophilicity of 7-azaisatins in MBH reactions, more activated alkenes were explored with 1a. Methyl and ethyl acrylates afforded products 3p and 3q, respectively, with comparable results to Wu’s work [7], albeit in a shorter time (24 h vs 2–3 d

Amino-functionalized (meth)acryl polymers by use of a solvent-polarity sensitive protecting group (Br-t-BOC)

• Helmut Ritter,
• Monir Tabatabai and
• Markus Herrmann

Beilstein J. Org. Chem. 2016, 12, 245–252, doi:10.3762/bjoc.12.26

• )-amino-protected monomers 2-((1-bromo-2-methylpropan-2-yl)oxycarbonylamino)ethyl (meth)acrylate 3a,b. For this purpose, 2-isocyanatoethyl (meth)acrylate 1a,b was reacted with 1-bromo-2-methylpropan-2-ol (2a). The free radical polymerization of (Br-t-BOC)-aminoethyl (meth)acrylates 3a,b yielded poly((Br-t

• )acrylates [2]. Therefore, for the synthesis of amino-containing (meth)acrylic monomers and polymers suitable amino-protecting groups are required. Classical protecting groups such as ammonium salts, F-MOC, Z- or t-BOC, respectively are readily available. Regarding to this aspect, we published some papers

Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation

• Jie Wang,
• Zhiqiang Qiu,
• Yiming Wang,
• Li Li,
• Xuhong Guo,
• Duc-Truc Pham,
• Stephen F. Lincoln and
• Robert K. Prud’homme

Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7

• the extent of intramolecular interactions between substituents in a single polymer chain and of intermolecular interactions between substituents in adjacent polymer chains. Consequently, the strength of interaction between the substituted poly(acrylates)s is substantially controlled by the variation

• % azobenzene-substituted poly(acrylate), PAAAzo, and two α-CD-substituted poly(acrylates) in which α-CD is substituted onto the poly(acrylate) backbone through either the C3- or C6-carbon of a D-glucopyranose subunit, PAA3α-CD and PAA6α-CD, respectively, which are 1.6 and 2.2% substituted (Figure 14) [67]. The

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• -deficient olefin (e.g., acrylates or acrylonitriles, type II or III). In these cases, full conversion and high yields can be achieved [18]. Although the problem with the CM reactions of olefins with electron-withdrawing groups, such as α,β-unsaturated ketones and esters, is partly solved [19][20], the

Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

• Antonia Di Mola,
• Maximilian Tiffner,
• Francesco Scorzelli,
• Laura Palombi,
• Rosanna Filosa,
• Paolo De Caprariis,
• Mario Waser and
• Antonio Massa

Beilstein J. Org. Chem. 2015, 11, 2591–2599, doi:10.3762/bjoc.11.279

• several methods to obtain rac-9 are available [32][33][34][35][36], it is worth noting that the asymmetric synthesis of 9 is one of the major obstacles when targeting the synthesis of chiral isoindolinones. The recently introduced intramolecular aza-Michael reactions of 2-substituted acrylates gave very

Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

• Takamichi Wakamatsu,
• Kazunori Nagao,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2015, 11, 2444–2450, doi:10.3762/bjoc.11.265

• alkenes with 9-BBN-H) to alkynoates to form β-disubstituted acrylates is reported. The addition occurred in a formal syn-hydroalkylation mode. The syn stereoselectivity was excellent regardless of the substrate structure. A variety of functional groups were compatible with the conjugate addition

• alkynoates might be possible through proton-trapping of an alkenylcopper intermediate. Herein, we report a copper-catalyzed conjugate addition of alkylboranes to alkynoates, providing a versatile approach to β-disubstituted acrylates [16][17][18][19]. The addition occurred in a formal syn-hydroalkylation

• acidic MeOH (vide infra). There was no reaction in the absence of a proton sourse. No hydroalkylation product at all could be found when alkyl-9-BBN 2a was replaced by (2-phenylethyl)boronic acid pinacolate ester; the substrates hardly reacted at all. A variety of β-disubstituted acrylates were

Self-assemblies of γ-CDs with pentablock copolymers PMA-PPO-PEO-PPO-PMA and endcapping via atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine

• Jing Lin,
• Tao Kong,
• Lin Ye,
• Ai-ying Zhang and
• Zeng-guo Feng

Beilstein J. Org. Chem. 2015, 11, 2267–2277, doi:10.3762/bjoc.11.247

• copolymers in aqueous solution, a multimodal molecular weight distribution (which usually results from the addition of methacrylates to the polymers of acrylates) was not shown in the GPC curves of the PR-based multiblock copolymers [18][19]. Given that nearly the same quantity of 5–8 γ-CDs were left after

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

• Meriem K. Abderrezak,
• Kristýna Šichová,
• Nancy Dominguez-Boblett,
• Antoine Dupé,
• Zahia Kabouche,
• Christian Bruneau and
• Cédric Fischmeister

Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201

• various cross metathesis reactions, the phosphine-free Hoveyda type second generation Zhan catalyst-1B [30] was selected to conduct this transformation. A recent study by Fogg rationalized the superiority of the Hoveyda catalyst vs the Grubbs catalyst in cross metathesis with acrylates showing that the

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• 28a,b) in excellent yields (82–92%). Involvement of acrylates 29a,b delivered lactones 30a,b in moderate yields (30a 41%, 30b 50%) upon treatment with catalyst 2 in dichloromethane at reflux conditions. However, 29a generated lactone 30a in 65% yield when the metathesis was performed using Grela’s

Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki–Heck cross-coupling reaction

• Jerzy Zakrzewski and
• Bogumiła Huras

Beilstein J. Org. Chem. 2015, 11, 1155–1162, doi:10.3762/bjoc.11.130

• Jerzy Zakrzewski Bogumila Huras Institute of Industrial Organic Chemistry, Annopol 6, 03-236 Warsaw, Poland 10.3762/bjoc.11.130 Abstract Cinnamic acid derivatives bearing a nitroxyl moiety (2,2,6,6-tetramethyl-1-oxyl-4-piperidyl 3-E-aryl acrylates) were synthesized in 30–100% yield using a

• saturated aliphatic acids (instead of unsaturated ones as acrylates) are reacted with simple aromatic compounds (as benzene) in the presence of palladium(II) chloride [20]. Due to the important biological activity of cinnamates, the incorporation of a spin label moiety, particularly a nitroxyl fragment, is

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• of such polymers prepared from side-chain-linked hydroxyproline or other hydroxyamino acids is their zwitterionic character, thereby separating them from more conventional amino acid acrylates prepared from the N-acylated amino acids. In the future, more resources could favourably be directed, by

Matsuda–Heck reaction with arenediazonium tosylates in water

• Ksenia V. Kutonova,
• Marina E. Trusova,
• Andrey V. Stankevich,
• Pavel S. Postnikov and
• Victor D. Filimonov

Beilstein J. Org. Chem. 2015, 11, 358–362, doi:10.3762/bjoc.11.41

• described by the group of Vallribera [9]. Arenediazonium tetrafluoroborates bearing only electron-donating groups (with the exception of chlorine) were effectively coupled with ethyl and tert-butyl acrylates only, while ethyl vinyl ketone, styrenes, allyl acetate, allyl benzene and methyl vinyl carbinol

• bromide [20] under harsh conditions with modest yields. The synthesized 3-chloropropyl cinnamates 3ba, 3bb, 3bg were not reported before. Styrene (1c) is less reactive than acrylates in Heck-type reactions. Notwithstanding, a range of stilbenes was synthesized stereoselectively with good yields and purity

New highlights of the syntheses of pyrrolo[1,2-a]quinoxalin-4-ones

• Emilian Georgescu,
• Alina Nicolescu,
• Florentina Georgescu,
• Florina Teodorescu,
• Daniela Marinescu,
• Ana-Maria Macsim and
• Calin Deleanu

Beilstein J. Org. Chem. 2014, 10, 2377–2387, doi:10.3762/bjoc.10.248

• [11] in presence of K2CO3 and triethylamine in DMF at 70 °C, or with activated alkenes, such as acrylates, acrylonitrile or diethyl malonate, in presence of triethylamine and an oxidant in DMF at 90 °C, led only to the normal cycloaddition products, i.e., pyrrolo[1,2-a]benzimidazoles [12]. When the

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• acrylates. In the presence of 10 mol % of the catalyst in toluene at room temperature, the [3 + 2] annulations of allenoates with alkenes proceeded smoothly, providing functionalized cyclopentenes in moderate to good yields (up to 87%) with excellent enantioselectivities (87–96% ee) and regioisomeric ratios

• moiety, Shi and co-workers developed an asymmetric [3 + 2] annulation of α-substituted acrylates with an allenoate (Scheme 26) [57]. The reactions proceeded smoothly in toluene at room temperature to give the corresponding functionalized cyclopentenes in high yields with moderate to good ee. The

Investigations of thiol-modified phenol derivatives for the use in thiol–ene photopolymerizations

• Sebastian Reinelt,
• Monir Tabatabai,
• Urs Karl Fischer,
• Norbert Moszner,
• Andreas Utterodt and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1733–1740, doi:10.3762/bjoc.10.180

• ]. Many efforts have been undertaken in the last decades aiming to face and overcome these limitations [1][4][5][6][7][8]. For instance the design of tailored (meth)acrylates based on calix[4]arenes [9][10] or tricyclodecane [11][12] backbones and use of ring-opening monomers as cyclopropane derivatives

N-Alkylated dinitrones from isosorbide as cross-linkers for unsaturated bio-based polyesters

• Oliver Goerz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 902–909, doi:10.3762/bjoc.10.88

• -dipolar cycloaddition with unsaturated bio-based polyester poly(isosorbide itaconate -co- succinate). Results and Discussion N-Alkylated dinitrones derived from acrylates and crotonates were prepared and evaluated in respect to their 1,3-cycloaddition with itaconic acid containing polyester resins. To

• . Synthesis of Z-configurated model compounds 3a/b from E-benzaldoxime and acrylates 2a/b. Proposed molecular interactions of nitron 3a and dimethyl itaconate (4). 1,3-Dipolaric cycloaddition of nitrones 3a/b with dimethyl itaconate (4). Synthetic route to bio-based dinitrones derived from isosorbide

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• delivered, e.g., by household lamps and LED bulbs) can be used; this is a catalytic process without loss of efficiency with irradiation. Photopolymerization under sunlight becomes reachable. The production of the radical or cationic initiating species for the FRP of acrylates or the FRPCP of epoxides

• (FRP) of acrylates: The experiments were carried out in laminated conditions or under air. The prepared formulations deposited on a BaF2 pellet (25 µm thick) were irradiated (see the irradiation devices). The evolution of the double bond content was continuously followed by real time FTIR spectroscopy

• ; Scheme 11) [64]. All these described systems, producing radicals, cations or radical cations, allow efficient CP and FRPCP of cationic monomers, FRP of acrylates, simultaneous radical/cationic polymerization of epoxide/acrylate blend. The reactions can be carried out (see in [45][46][47][48][49][50][51

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• also been tested (acrylates, maleic anhydride) giving no products or unsatisfactory results. A large range of aldehydes, as aliphatic, electron-rich or electron-poor benzaldehyde, could be used. Only very hindered aldehydes did not afford any product and both mono- and disubstituted arylhydrazines have

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• electrophilic alkenes have not been exploited. Toste´s group published an efficient 1,3-dipolar cycloaddition (1,3-DC) between alanine, phenylalanine and allylglycine derived azlactones with maleimides and acrylates employing dimetallic (S)-Cy-Segphos(AuOBz)2 complex 1 as a catalyst (2 mol %) in the absence of

• unexpected regioselectivity of the 1,3-DC depicted in Scheme 6, calculations within the DFT framework were performed. In the accepted mechanism of the metal catalyzed 1,3-DC of azomethine ylides and acrylates, the α-carbon atom of the azomethine ylide (C2 in Figure 5) reacts with the β-carbon of the acrylate

• this kind of reactive species, the reaction yields cycloadducts possessing a standard regioselectivity in 1,3-DC with acrylates [38]. Since our goal was to understand the origins of the unusual regioselectivity observed in the reaction between dipoles of type Ylide-I with acrylates, trimethylphosphine

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• methods utilising cycloadditions of electron-rich oxazoles and acrylates [17][18] tri- and tetrazines with alkenes/alkynes [19] or pyrones with nitriles [20] have been used successfully to access specifically functionalised pyridines which are difficult to prepare by the more direct condensation routes. A