Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• and exhibit a negative solvatochromism. An analysis of the kinetics of the zwitterion formation was performed for three Michael acceptors (acrylonitrile, methyl acrylate, and acrylamide) in two different solvents (chloroform and methanol). The results revealed the proton transfer step necessary to

• , Figure S47). A similar oligomerization reaction has been reported for cyanoacrylates [40]. Apart from the adducts of these two very weak Michael acceptors, the zwitterionic species 2a–i described herein are quite stable. The stability of the zwitterions was evaluated exemplarily using the methyl acrylate

• , which can be assigned to the phosphine oxide of 1 [41]. No free Michael acceptor (methyl acrylate) could be observed in the NMR spectrum (Supporting Information File 1, Figure S50). The 31P NMR spectrum (Supporting Information File 1, Figure S51) confirms the presence of the phosphine oxide of 1 as the

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• in a Michael addition with methyl acrylate, affording aldehyde 4 (Scheme 1). Instead of the original Wittig reaction [13], a Horner–Wadsworth–Emmons reaction using diethyl (2-methylallyl)phosphonate and BuLi led to a higher yield and formation of the pure (E)-isomer 5. The required phosphonate was

• , ii) rt, 2.5 h; b) i) methyl acrylate (1.3 equiv), MeCN, 90 °C, 42.5 h, ii) dest. H2O, AcOH, reflux, 1 h; c) i) diethyl (2-methylallyl)phosphonate (1.3 equiv), n-BuLi (1.3 equiv), THF, −78 °C, 35 min, ii) 4 (1.0 equiv), THF, −78 °C, 1 h, iii) rt, 1.5 h; d) i) LiAlH4 (1.2 equiv), Et2O, 0 °C, 15 min ii

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• several cases, a good regioselectivity was achieved for complex molecules. Quinuclidine cation radicals were also involved in the generation of nucleophilic α-hydroxyalkyl radicals from alcohols for the addition to the electron-deficient C=C bond of methyl acrylate followed by lactonization [107] (Scheme

Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity

• Naoki Kise and
• Toshihiko Sakurai

Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95

• addition of an O-trimethylsilyl anion C, which is formed by a two-electron reduction of substrate 1 and O-trimethylsillylation, to 2a (path b). Unlike the two reactions previously reported by us that are presumed to proceed with the addition of an anion species (Scheme 1 and Scheme 2) [5][6], methyl

• acrylate (2c) is much less reactive as an acceptor in this reaction as shown in Scheme 6. The main product in this case was the same dimeric phthalide 9 as the product without the acceptor. These results suggest that this reaction proceeds with the radical addition of A to form anion D (path a). Next, the

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• 1-substituted 2-ethoxy-1,2-azaphospholidine-4-carboxylate 2-oxides 203 were synthesized in 70% and 39% yields, respectively, from ethyl 2-((chloro(ethoxy)phosphoryl)methyl)acrylate (202) and benzyl- and adamantylmethylamines via aza-Michael addition and intramolecular nucleophilic substitution. The

• -phenylphosphonamidates 240a (R’ = OEt) and diaryl-N-phenylphosphinamides 240b–d (R’ = Ar), respectively, with methyl acrylate (241) via the rhodium-catalyzed oxidative coupling and subsequent intramolecular aza-Michael addition. Methyl acrylate (241) could be replaced by various electron-deficient olefins 244, including

• ethyl and butyl acrylates, but-3-en-2-one, N,N-dimethylacrylamide, acrylonitrile, and phenyl vinyl sulfone. In addition, ethyl 1-arylvinyl-N-phenylphosphonamidates 246 were able to react with methyl acrylate (241), affording methyl 2-(3-aryl-2-ethoxy-2-oxo-1-phenyl-1,5-dihydro-1,2-azaphosphol-5-yl

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• could be isolated and characterized, proving the generation of acyl radicals in reaction media. Another evidence of DABCO as HAT catalyst for aldehyde activation could be obtained by the radical trapping with methyl acrylate. In this case, Giese-type product 19 was isolated in 20% yield (Scheme 2, see

• addition experiment with methyl acrylate (Supporting Information File 1, Table S5), along with the strong dependence of aryl bromide electronics on the yield indicate the protagonism of the nickel-aryl bromide system. We hypothesized a HAT step by the bromine radical, generated by nickel complex photolysis

Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF₃·OEt₂ catalysis

• Karthikeyan Soundararajan,
• Helen Ratna Monica Jeyarajan,
• Raju Subimol Kamarajapurathu and
• Karthik Krishna Kumar Ayyanoth

Beilstein J. Org. Chem. 2021, 17, 2186–2193, doi:10.3762/bjoc.17.140

• -ium-2-ide (7a) was synthesised at room temperature by treating methyl acrylate, hydrazine hydrate and benzaldehyde in a yield of 67%. On treating the synthesised azomethine imine 7a (1.2 mM) and 2-substituted-1H-indenes 6b and 6c (1 mM) in toluene at 70 °C affords 8a and 8b via [3 + 2] cycloaddition

• ; found, 174.0706 Synthesis of 1-benzylidene-3-oxopyrazolidin-1-ium-2-ide (7a) A methyl acrylate (0.0225 mol) solution was added drop-wise to the solution of hydrazine monohydrate (0.0205 mol) in 20 mL of ethanol. This solution was stirred at 78 °C for 4 hours; the solvent was evaporated and the residue

Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines

• Zara M. Seibel,
• Jeffrey S. Bandar and
• Tristan H. Lambert

Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134

• optimize this process, we selected the addition of alanine imine 1 to methyl acrylate as our test reaction (Table 1). We found that the previously reported cyclopropenimine 4 catalyzed this transformation with 90% conversion and 84% ee in 24 hours at ambient temperature (Table 1, entry 1). The desired

• and several natural products with pyroglutamate substructures. Effect of the aryl substituent on reaction efficiency and selectivity. Proposed transition state model. Optimization of the cyclopropenimine-catalyzed addition of alanine imine 1 to methyl acrylate. Substrate scope of amino ester imine

• additions to methyl acrylate. Supporting Information Supporting Information File 314: Experimental details, characterization data, spectra, and HPLC traces. Acknowledgements We thank the Leighton group (Columbia University) for use of their instrumentation. Funding Financial support for this work was

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• very low conversion (pulegone, 22%) or did not react under the optimized conditions, even after 24 h of reaction time (methyl cinnamate, methyl acrylate, methyl methacrylate, isobutyl acrylate). For cycloalkenes (Table 2, entries 10–12) different oxidation patterns were observed depending on the alkene

Coupling biocatalysis with high-energy flow reactions for the synthesis of carbamates and β-amino acid derivatives

• Alexander Leslie,
• Thomas S. Moody,
• Megan Smyth,
• Scott Wharry and
• Marcus Baumann

Beilstein J. Org. Chem. 2021, 17, 379–384, doi:10.3762/bjoc.17.33

• solid K2CO3 packed into an Omnifit glass column (10 cm length, 10 mm i.d., filled with powdered K2CO3) was trialed as a heterogeneous reagent. A simple flow process was quickly realized in which a solution of the carbamate substrate (0.5 M toluene, 1.0 equiv) containing either acrylonitrile or methyl

• acrylate (1.2 equiv) was pumped at a flow rate of 0.5 mL/min through the K2CO3 column heated to 100 °C. The resulting short residence time (≈5 min) within the column was sufficient to give a high conversion of the substrates tested (Scheme 5, method 1). In a complementary approach a biphasic liquid–liquid

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• temperatures, e.g., caused by engine heat. Common VIIs are based on poly(methyl acrylate) (PMA) [1]. These systems are able to increase the viscosity at elevated temperatures by increasing their hydrodynamic radius [2]. This is based on the fact that PMAs occur as coiled polymer chains with lower hydrodynamic

Azidophosphonium salt-directed chemoselective synthesis of (E)/(Z)-cinnamyl-1H-triazoles and regiospecific access to bromomethylcoumarins from Morita–Baylis–Hillman adducts

• Soundararajan Karthikeyan,
• Radha Krishnan Shobana,
• Kamarajapurathu Raju Subimol,
• J. Helen Ratna Monica and
• Ayyanoth Karthik Krishna Kumar

Beilstein J. Org. Chem. 2020, 16, 1579–1587, doi:10.3762/bjoc.16.130

• [52]. A mixture of benzaldehyde (1.1 g, 1.14 mL, 0.01 mol), methyl acrylate (2.05 g, 2.15 mL, 0.023 mol) and DABCO (0.87 g, 0.0077 mol) in chloroform (5 mL) was stirred at room temperature for 7 d. The reaction mixture was quenched with 10% aqueous hydrochloric acid (50 mL) and washed repeatedly with

Recent synthesis of thietanes

• Jiaxi Xu

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

• ) reacted with electron-poor olefins, such as acrylonitrile (187b), methyl acrylate (187c), and cis- and trans-1,2-dichloroethenes 188, under photochemical conditions, giving 2-silylthietanes 317 and 318 in a regio- and highly stereoselective manner. However, silyl thietanes without any regio- or

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• -vinylpyrroles 16a,b were chosen as the dienes to evaluate the reactivity with diverse dienophiles. The reaction of acrolein, methyl acrylate, maleic anhydride and maleimide (R3 = H, 7a) in xylene by heating up to 150 °C failed to provide the corresponding adducts. It was possible to recover the starting

• , a decrease in the electronic density should be anticipated for the methyl acrylate dienic moiety. According to the perturbation theory [57], such an effect would cause a reduction in the cycloaddition reactivity, because the diene needs electron-donating substituents to enhance it (under normal

[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin

• Margareta Sohora,
• Leo Mandić and
• Nikola Basarić

Beilstein J. Org. Chem. 2020, 16, 1296–1304, doi:10.3762/bjoc.16.110

• most probably undergoes decarboxylation delivering 1AMY from the S1 state [49]. In CH3CN, 1AMY decays with a rate constant of 2.9 × 106 M−1 s−1, and reacts with methyl acrylate in [3 + 2] cycloaddition with the rate constant 2.7 × 107 M−1 s−1 [49]. Protic solvents such as CH3OH or H2O quench

Diversity-oriented synthesis of 17-spirosteroids

• Benjamin Laroche,
• Thomas Bouvarel,
• Martin Louis-Sylvestre and
• Bastien Nay

Beilstein J. Org. Chem. 2020, 16, 880–887, doi:10.3762/bjoc.16.79

• of the obtained succinic anhydride derivative (16b) upon purification. Other unsymmetrical dienophiles (methyl acrylate, methyl propiolate) gave complex mixtures of regio- and/or stereoisomers. The reaction of lynestrenol enyne 6a with N-phenylmaleimide was also performed to furnish compound 17a in

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• carried out employing indole (1a), methyl acrylate (2a), and 3 mg of the RuNC. Different oxidants as well as solvents were explored for the reaction. From the optimisation reactions and the control experiments, it was concluded that the reaction with Cu(OAc)2 as the oxidant in DMF/DMSO, 9:1, v/v at 130 °C

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

• reactions and a newly developed deoxygenative aromatization procedure. The first enantioselective Diels–Alder reaction, which is an intermolecular cycloaddition and lactonization between (Z)-3-iodo-4-methylpenta-2,4-dien-1-ol (29) and methyl acrylate (30) in the presence of Mikami’s (binol)TiCl2 catalyst to

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

• , the cross metathesis (CM) between alcohol 8 and the electron-deficient cross partner methyl acrylate (10, Table 1). All reactions were run at 36 °C in D2O promoted either by microwave (µW) or ultrasound (US) irradiation, and for comparison purposes also with standard magnetic stirring. In the case of

• is in agreement with the known fact that in protic solvents ruthenium hydrides are formed leading to isomerisation byproducts [66]. Finally, we were pleased to see that the use of ultrasound or microwave irradiation were beneficial for the CM of alcohol 8 with methyl acrylate (10, Table 1, entries 5

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• model compound was first subjected to CM with methyl acrylate. When the reaction was performed in the presence of Ru-based catalysts, in CH2Cl2, either at reflux temperature or at 20 °C, it gave a mixture of monometathesised products ((±)-21 and (±)-22) after 6 h together with a large amount of

• derivative (80 mg) in anhydrous CH2Cl2 (15 mL), catalyst (5 mol %, see Table) and methyl vinyl ketone or methyl acrylate (4 equiv) were added and the mixture was stirred for the time and temperature indicated in text. After completion of the reaction (monitored by TLC), the mixture was concentrated under

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• ) compared to the conventional method that generally takes days to a week for completion. The reaction of methyl acrylate with different para-substituted aryl aldehydes in the presence of 20 mol % 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyst at 0.5–45 h yielded the MBH products in 28–98% yield [53]. Wittig

Synthesis of benzothiophene and indole derivatives through metal-free propargyl–allene rearrangement and allyl migration

• Jinzhong Yao,
• Yajie Xie,
• Lianpeng Zhang,
• Yujin Li and
• Hongwei Zhou

Beilstein J. Org. Chem. 2017, 13, 1866–1870, doi:10.3762/bjoc.13.181

• products in good yields (2a–k). A variety of substituents, such as p-COOEt, p-COCH3, dichloro, p-NO2, p-CF3 and p-CN were well-tolerated during the reaction, leading to 2a–f in 54–83% yield. The presence of methyl acrylate or pyridine was also well-tolerated, as exemplified in the formation of 2g,h in 48

Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

• Michal Medvecký,
• Igor Linder,
• Luise Schefzig,
• Hans-Ulrich Reissig and
• Reinhold Zimmer

Beilstein J. Org. Chem. 2016, 12, 2898–2905, doi:10.3762/bjoc.12.289

• lithium chloride [35] leading to the expected coupling products syn-13 and syn-14 in 39% and 82% yield, respectively (Scheme 5). In both cases, only the E-configured 2-substituted alkyl acrylates were isolated. The moderate yield in the Heck reaction with methyl acrylate 12a is very likely caused by the

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

• Valeria Corne,
• Ariel M. Sarotti,
• Carmen Ramirez de Arellano,
• Rolando A. Spanevello and
• Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

• slightly stronger interaction for 6a (see Supporting Information File 1 for further details). To shed light on these issues, we next computed the interaction energies for the complexes of methyl acrylate (7) and 4-trifluoromethylanisole (8), 4-methoxyanisole (9) or anisole (10), (Scheme 2). For the

• (in kcal/mol) computed for 6d and 6b (in grey). X-ray thermal ellipsoid plot of 6a (50% probability level) showing the labeling scheme (hydrogen and carbon labels have been omitted for clarity). Synthesis of acrylates 6a,b. Complexes between methyl acrylate (7) and representative anisole derivatives