Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• triphenylphosphine (TPP) in catalyzing oxa-Michael additions. A matrix consisting of three differently strong Michael acceptors and four alcohols of varying acidity was used to assess the activity of the three catalysts. All test reactions were performed with 1 mol % catalyst loading, under solvent-free conditions

• -Michael addition. Triphenylphosphine (TPP), (4-methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP). The catalysts were investigated in the reaction of four different Michael acceptors with four different alcohols. In the oxa-Michael addition, the zwitterion i, initially

• by triphenylphosphine (TPP), (4-methoxyphenyl)diphenylphosphine (MMTPP), and tris(4-methoxyphenyl)phosphine (TMTPP). Reaction conditions: 1 equiv Michael acceptor, 2 equiv alcohol (in case of 3, 3 equiv alcohol), 1 mol % catalyst (with respect to the Michael acceptor), 1 h and 24 h (bars above grey

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• using 0.6 mol % of tetrakis(triphenylphosphine)palladium(0) and 1.2 mol % of copper iodide (Scheme 2, Table 1). The reaction proceeded chemoselectively at the two carbon–bromine bonds giving 2,4-bis(phenylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine (4a). This result was not entirely predictable, as the

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

Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

• Jan Bartáček,
• Jan Svoboda,
• Martin Kocúrik,
• Jaroslav Pochobradský,
• Alexander Čegan,
• Miloš Sedlák and
• Jiří Váňa

Beilstein J. Org. Chem. 2021, 17, 1048–1085, doi:10.3762/bjoc.17.84

• systematic study of phosphine-based Pd complexes was done by Wong et al. in 2014. The palladacycle PdL6 was used in combination with triphenylphosphine and K3PO4 acting as a base. The highest enantioselectivity of 99% ee of a model addition of phenylboronic acid to 2-cyclohexenone was achieved in dioxane as

Effective microwave-assisted approach to 1,2,3-triazolobenzodiazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition

• Maryna O. Mazur,
• Oleksii S. Zhelavskyi,
• Eugene M. Zviagin,
• Svitlana V. Shishkina,
• Vladimir I. Musatov,
• Maksim A. Kolosov,
• Elena H. Shvets,
• Anna Yu. Andryushchenko and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2021, 17, 678–687, doi:10.3762/bjoc.17.57

• bond. Usually, AAC reactions on non-terminal alkynes are performed with ruthenium catalysis [21] that determined our decision to start screening conditions using the chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium(II) complex ((Cp)Ru(PPh3)2Cl) as catalyst. However, carrying out the reaction

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• thiophiles. First, we added triphenylphosphine (1 equiv) but an even more complex mixture of products resulted. Much better results were obtained when trimethyl phosphite was used but this strongly depended on the used molar ratio: the best yield of the product 7aa (83%) was achieved when using 1.5 equiv of

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• reduction of dibromodifluoromethane was also used for the approach of Burton and Naae (Scheme 4), which is again suitable for electron-rich alkenes [19]. Dibromodifluoromethane reacted with triphenylphosphine to give a phosphonium salt, which then decomposed to difluorocarbene. The yields from this method

• : PDFA is available from the reaction of triphenylphosphine with halodifluoroacetate salts such as BrCF2CO2K. It exists as a free-flowing white solid that is not sensitive to air or moisture [33]. Upon heating to 80 °C in N-methylpyrrolidone, the compound decarboxylates and acts as a source of the ylide

• (Scheme 23) [64]. Fürstner et al. [67] showed that (trifluoromethyl)gold(I)triphenylphosphine in dichloromethane can be used for the production of difluorocyclopropanes at low temperatures. The advantage of the method is its stereoselectivity. The disadvantages include the stoichiometric use of gold, low

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

•  19). For the synthesis of inthomycin B ((+)-2), a Suzuki coupling reaction between (E,E)-128 and (Z)-(+)-130a was performed in the presence of palladium(II) acetate, triphenylphosphine, and aqueous sodium carbonate to give (E,E,Z)-triene (+)-131 selectively in 64% yield. Treatment of triene (+)-131

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• ). The reaction between ethyl 2,3-butadienoate (82) and diethyl fumarate (83) in the presence of 10 mol % of triphenylphosphine afforded trans-84 in 67% yield. Under the same conditions, the use of diethyl maleate in place of diethyl fumarate (83) will give cis-84 in 46% yield (not shown). Lu and co

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• obtained using the less reactive triphenylphosphine dicobaltpentacarbonyl complex 63 as the catalyst (Scheme 35). In a later study [72], Riera and Fustero generalized the use of trifluoromethylalkynes as substrates for the PKR. The copper-catalyzed trifluoromethylation of terminal alkynes described by Qing

Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner–Wadsworth–Emmons-based approach

• Rhys A. Lippa,
• John A. Murphy and
• Tim N. Barrett

Beilstein J. Org. Chem. 2020, 16, 1617–1626, doi:10.3762/bjoc.16.134

• , GlaxoSmithKline disclosed a route to a fluoropyrrolidine 6 using a Wittig reaction between phosphonium salt 4 and aldehyde 5 [2]. The synthesis of phosphonium salt 4 (itself requiring 6 steps including partial saturation of a 1,8-naphthyridine moiety) and the formation of the triphenylphosphine oxide byproduct in

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

• ascertained a gradual decrease in the yield of 3a (Table 1, entries 5 and 6). The outcome of this analysis might have been due to the formation of large amounts of the byproduct triphenylphosphine oxide, which impeded the purification process and decreased the yield of 3a. Alternative Cu(I) catalysts, CuCl

• the presence of CuI (5 mol %), triphenylphosphine (1 equiv), bromomethane (1.1 equiv), and sodium azide (2 equiv). Unexpectedly, the reaction yielded (Z)-methyl-2-(bromomethyl)-3-phenylacrylate (58%) over the expected triazole. Similarly, the MBH adduct derived from furan, 1i, and phenylacetylene (2b

• outcome of this process was the phosphonium-protected MBH moiety Ib and hydrazoic acid. The counter ion bromine facilitated the nucleophilic attack at the vinylic centre of Ib and the spontaneous removal of triphenylphosphine oxide to yield IIb. A consecutive intramolecular nucleophilic attack of the

Recent synthesis of thietanes

• Jiaxi Xu

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

• -thiofuranoside 141 by reduction with triphenylphosphine [55] (Scheme 27). 2.2.3 Synthesis via the nucleophilic ring-opening of three-membered heterocycles and subsequent displacement from halomethyloxirane derivatives: Chloromethyloxirane (142a) and its 2 and 3-phenyl derivatives 142b and 142c reacted with H2S

• synthesis of liquid crystal materials. They synthesized a chiral thietane 175 from the chiral thiirane-2-methanol 172 with 3-nitrophenol (173) under Mitsunobu conditions (Scheme 36). In the synthesis, the alcohol 172 first reacted with triphenylphosphine to generate thiirane 174, which underwent nucleophile

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• potassium acetate (KOAc) and dichlorobis(triphenylphosphine)palladium(II) in 1,4-dioxane [36][37]. Upon chromatography (9-hexylcarbazole-3-yl)boronic acid pinacol ester (5) was obtained as a liquid in good yield. (9-Hexylcarbazole-3-yl)boronic acid pinacol ester (5) was subjected to Suzuki–Miyaura reaction

• either with 2-bromopyridine-4-carbaldehyde (6a) or 2-bromopyridine-5-carbaldehyde (6b) in the presence of potassium carbonate and bis(triphenylphosphine)palladium(II) dichloride in tetrahydrofuran [2]. Upon repeated purification by chromatography, compounds 7a and 7b were obtained as liquids in good

• ), 0.86 (t, J = 7.0 Hz, 4H). (9-Hexylcarbazole-3-yl)boronic acid pinacol ester (5): 5 was synthesised as reported previously [36][37]. Bis(pinacolato)diboron (423 mg, 1.7 mmol), potassium acetate (446 mg, 4.5 mmol) and dichlorobis(triphenylphosphine)palladium(II) (35 mg, 0.05 mmol) catalyst were added to

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

• double bonds into the corresponding (Z)-monohalogenated derivatives using palladium(II) acetate, triphenylphosphine and tributyltin hydride. Following this procedure, we were able to obtain (Z)-bromide 4 in four steps and an overall yield of 39% [21][22][23][24]. Cross coupling of fragments 3 and 4 The

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• ethanol (60 mL) and triphenylphosphine (10 mmol) was put in an oil bath at 70 °C under a nitrogen atmosphere. Then, hydrated rhodium(III) chloride (1.5 mmol) dissolved in anhydrous ethanol (10 mL) was added to the solution under stirring and the resulting solution was kept at gentle reflux for 2.5 h

Copper-catalyzed enantioselective conjugate reduction of α,β-unsaturated esters with chiral phenol–carbene ligands

• Shohei Mimura,
• Sho Mizushima,
• Yohei Shimizu and
• Masaya Sawamura

Beilstein J. Org. Chem. 2020, 16, 537–543, doi:10.3762/bjoc.16.50

• work of Stryker and co-workers on triphenylphosphine-stabilized copper hydride complexes [1][2], copper hydrides have been widely used for conjugate reductions of α,β-unsaturated carbonyl compounds [3]. Especially a chiral copper catalyst combined with a stoichiometric amount of a silane reagent, which

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• . Finally, the desired ligands were obtained by palladium-catalyzed phosphorylation with triphenylphosphine in DMF [92]. Resolution with palladium amine complexes and subsequent crystallization resulted in the enantiomerically pure ligands 95. C2-Symmetric atropisomeric diphosphines are among a diverse

Functionalization of the imidazo[1,2-a]pyridine ring in α-phosphonoacrylates and α-phosphonopropionates via microwave-assisted Mizoroki–Heck reaction

• Damian Kusy,
• Agata Wojciechowska,
• Joanna Małolepsza and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 15–21, doi:10.3762/bjoc.16.3

• , replacing palladium acetate by tetrakis(triphenylphosphine)palladium(0), Pd(PPh3)4, or bis(dibenzylideneacetone)palladium(0), Pd(dba)2, resulted in a reduction in the yield and a partial recovery of substrate 1a (Table 1, entries 13 and 14). In the next series of experiments, different amines were tested

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• ]. FDA was first used as cross-linker to knit aromatic building blocks [15]. Researchers used this method to knit triptycenes [16], triphenylphosphine [4], benzimidazole, 1,3,5-triphenylbenzene [17], carbazole [18], naphthol-based monomers [10] etc. with FDA to obtain various HCPs, which exhibited

A new approach to silicon rhodamines by Suzuki–Miyaura coupling – scope and limitations

• Thines Kanagasundaram,
• Antje Timmermann,
• Carsten S. Kramer and
• Klaus Kopka

Beilstein J. Org. Chem. 2019, 15, 2569–2576, doi:10.3762/bjoc.15.250

• optimizations of the reaction conditions could lead to the silicon rhodamine 22 in moderate yields, an inseparable impurity of the cationic fluorophore was detected. After identifying this impurity as the tetraphenylphosphonium cation, we exchanged the triphenylphosphine ligand of the catalyst with dppf (1,1

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• chromatography on silica gel. For the purpose of this study, (1R,4R,5R)-apopinenol (16) was subjected to the Mitsunobu reaction to obtain the product with inverted configuration at C4. Alcohol 16 was reacted with diisopropyl azodicarboxylate, triphenylphosphine, and p-nitrobenzoic acid in THF [30]. 1H NMR

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• nitrate complex was thus soluble in chlorinated solvents. In the presence of the bulky triphenylphosphine silver triflate salt, a monocoordination occurred between Ag(I) and each sulfur atom of ligand 1 leading to a discrete complex (syn-1)·(Ph3PAgOTf)2, as revealed by 1H NMR and X-ray (Figure 3). The

• steric hindrance also induced the access to a racemic mixture of (R,R)- and (S,S)-complexes where triphenylphosphine groups were located at the opposite sides of the anthracene core. The crystallographic structures of 1a, 1c and 1d showed that both ligand syn-1 and the nature of silver anion impacted on