Molecular diversity of the reactions of MBH carbonates of isatins and various nucleophiles

• Zi-Ying Xiao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21

• addition of Lewis base is needed. When triphenylphosphine or tri(n-butyl)phosphine were involved in the reaction, the similar SN2’ substitution of tri(n-butyl)phosphine with the elimination of carbon dioxide and tert-butoxide anion gives the phosphonium salt C. Then, the deprotonation of phosphonium salt C

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Structure and thermal stability of phosphorus-iodonium ylids

• Andrew Greener,
• Stephen P. Argent,
• Coby J. Clarke and
• Miriam L. O’Duill

Beilstein J. Org. Chem. 2024, 20, 2931–2939, doi:10.3762/bjoc.20.245

• 1j (cf. φ (3) = 5°) [28], the arene ring is virtually in the same plane as the 3-centre-4-electron bond, giving rise to the most stable compounds in our series (Tonset (2) = 225 °C; Tonset (1j) = 172 °C). By contrast, mesityl phosphonium ylid 1k showed very low thermal stability (Tonset = 74 °C, ΔH

• = 70 J/g). Ortho-methyl groups have been shown to destabilise iodonium species by inducing a larger hypervalent twist [31][38][39], and while we were unable to obtain a crystal structure of 1k, a large dihedral angle (φ = 43°) was observed in Moriarty’s ortho-methylbenzene phosphonium ylid 4 [24

• )triphenylphosphonium salt 6 and (iodomethyl)triphenyl-phosphonium salt 7. Homolytic or heterolytic scission of the I–C(ylid) bond with loss of ArI (path a) would result in a carbene, though it is unclear how this would transform to compound 6. Alternatively, scission of the I–C(Ar) bond with loss of benzyne (path b

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

• Jonas Holste,
• Paul Weldon,
• Donald Boyer and
• Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

• solvent and excess methyl iodide were removed in vacuo. Analytical data were identical to those reported [31]. Methyl 4,6-dimethyldodec-5-enoate (6): Phosphonium salt 5 (185 mg, 0.4 mmol) was dissolved in dry, degassed THF (10 mL). LiHMDS in hexane (1 M, 0.6 mL, 0.6 mmol) was added slowly at −10 °C and

A review of recent advances in electrochemical and photoelectrochemical late-stage functionalization classified by anodic oxidation, cathodic reduction, and paired electrolysis

• Nian Li,
• Ruzal Sitdikov,
• Ajit Prabhakar Kale,
• Joost Steverlynck,
• Bo Li and
• Magnus Rueping

Beilstein J. Org. Chem. 2024, 20, 2500–2566, doi:10.3762/bjoc.20.214

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• pyridine, triphenylphosphine or tetraethylammonium cyanide, the corresponding pyridium 109, phosphonium 111 and cyano hydrazones 113 were obtained, respectively (Scheme 21) [69]. In 2020, Ruan and Sun et al. communicated the electrochemical dehydrogenative coupling between (hetero)aromatic or aliphatic

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

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

• University of Technology, Stremayrgasse 9, 8010 Graz, Austria 10.3762/bjoc.20.6 Abstract The reactions of 2,4-di-tert-butyl-6-(diphenylphosphino)phenol and various Michael acceptors (acrylonitrile, acrylamide, methyl vinyl ketone, several acrylates, methyl vinyl sulfone) yield the respective phosphonium

• phenolate zwitterions at room temperature. Nine different zwitterions were synthesized and fully characterized. Zwitterions with the poor Michael acceptors methyl methacrylate and methyl crotonate formed, but could not be isolated in pure form. The solid-state structures of two phosphonium phenolate

• molecules were determined by single-crystal X-ray crystallography. The bonding situation in the solid state together with NMR data suggests an important contribution of an ylidic resonance structure in these molecules. The phosphonium phenolates are characterized by UV–vis absorptions peaking around 360 nm

Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates

• Xing Liu,
• Wenjing Shi,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143

• efficient synthesis of spiro[azepine-4,3'-indoline] derivatives via the [4 + 3] cycloaddition reaction of bromo-substituted isatin-derived MBH adducts and N-(o-chloromethyl)arylamides. In this efficient protocol, the reactive allylic phosphonium ylides and aza-o-quinone methides were generated in situ and

Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• showcased broad applicability, operational simplicity, and utilized easily obtainable and air-stable phosphonium salts 54 as convenient photoinduced Rf radical reagents. Conclusion In recent years, the field of synthetic chemistry has experienced significant advancements in iodide/phosphine-based photoredox

• . PPh3-catalyzed alkylative iododecarboxylation with LiI. Visible-light-triggered iodination facilitated by N-heterocyclic carbenes. Visible-light-induced photolysis of phosphonium iodide salts for monofluoromethylation. Funding This work was financially supported by the Central University Basic

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• formation of compound 92, which was reduced to the corresponding alcohol and then converted into the bromide 94. Ozonolysis followed by reaction with triphenylphosphine gave the corresponding phosphonium salt 96, which was subjected to different conditions for the intramolecular Wittig reaction. The best

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• , does not undergo acylation during the catalysis. Finally, we compared our catalytic system with commercially available imidazolium and phosphonium-based ILs (Table 4). The imidazolium-based IL [EMIm]NTf2 converts anisole with a yield of 77% (see Table 4, entry 1), whereas [BMIm]NTf2 shows a similar

• performance as TAAIL 6. Using IL 1,3-dibutyl-2-methylimidazolium NTf2 (Table, entry 3), carrying no hydrogen atom at the C2 position of the imidazolium ring, 86% of product were obtained. The phosphonium-based IL [P66614]NTf2 again shows an inferior performance compared to TAAIL 6. Upon changing the anion of

Organophosphorus chemistry: from model to application

• György Keglevich

Beilstein J. Org. Chem. 2023, 19, 89–90, doi:10.3762/bjoc.19.8

• derivatives. In another study, the synthesis of bis(chlorophenyl)acetylenes that were useful for the preparation of 1,2,3-tris(chlorophenyl)cyclopropenylium bromides was accomplished [3]. The latter species were converted to tributyl(1,2,3-tris(chlorophenyl)cyclopropenyl)phosphonium bromides, affording 3,4,5

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

Synthesis and electrochemical properties of 3,4,5-tris(chlorophenyl)-1,2-diphosphaferrocenes

• Almaz A. Zagidullin,
• Farida F. Akhmatkhanova,
• Mikhail N. Khrizanforov,
• Robert R. Fayzullin,
• Tatiana P. Gerasimova,
• Ilya A. Bezkishko and
• Vasili A. Miluykov

Beilstein J. Org. Chem. 2022, 18, 1338–1345, doi:10.3762/bjoc.18.139

• Federation 10.3762/bjoc.18.139 Abstract A novel representative of sodium 3,4,5-triaryl-1,2-diphosphacyclopentadienide containing a chloro substituent in the meta-position of the aryl groups was obtained with a high yield based on the reaction of tributyl(1,2,3-triarylcyclopropenyl)phosphonium bromide and

• ; electrochemical properties; phosphacyclopentadienide anion; phosphaferrocene; phosphonium salt; phosphorus heterocycle; Introduction Among the various heterometallocenes reported to date, phosphaferrocenes are by far the most investigated because of their structural and electronic features [1][2] and remain the

• tributyl(1,2,3-triarylcyclopropenyl)phosphonium bromides 6 containing a Cl substituent in the meta- or para-position of each aryl group. This was done by reaction of appropriate 1,2,3-triarylcyclopropenylium bromides 5 with PBu3 at 25 °C in THF in 34 and 39% yield (Scheme 2). The structures of 6 were

A Se···O bonding catalysis approach to the synthesis of calix[4]pyrroles

• Qingzhe Tong,
• Zhiguo Zhao and
• Yao Wang

Beilstein J. Org. Chem. 2022, 18, 325–330, doi:10.3762/bjoc.18.36

• phosphonium selenide catalysts which showed catalytic activity in assembly reactions [41], Michael addition reactions [41], Rauhut–Currier reactions [42], cyanosilylation reactions [43], and cycloaddition of vinylindoles through chalcogen–π bonding catalysis [44]. Our previous works demonstrated that Se···O

• bonding interactions between phosphonium selenides and carbonyls can significantly activate carbonyl groups [41][42][43], thus providing a new opportunity to develop carbonyl chemistry. To expand the catalysis capability of chalcogen bonding interactions, we envisioned that consecutive condensations

Strategies for the synthesis of brevipolides

• Yudhi D. Kurniawan and
• A'liyatur Rosyidah

Beilstein J. Org. Chem. 2021, 17, 2399–2416, doi:10.3762/bjoc.17.157

• liberated using TBAF to give compound 27 in 97% yield over two steps. The alcohol group in 27 was then oxidized to the corresponding aldehyde under Swern conditions and subsequently subjected to a Wittig reaction with a two-carbon phosphonium ylide reagent. The desired α,β-unsaturated ester 28 was then

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• recently, the strategy via introducing secondary interactions for the design of the bifunctional catalysts achieved wide application in asymmetric reactions [74]. Wu et al. described a Mannich asymmetric addition of cyanocoumarins 39 to isatin imines 112 catalyzed by an amide-phosphonium salt 114. This

• %) providing excellent results, besides the use of only 0.1 mol % of amide-phosphonium salt for the synthesis of coumarin derivatives. Some methodologies have also proven to be highly efficient in one-pot and gram-scale procedures, which turns to be more environmentally benign. Nevertheless, studies are still

• of 2-hydroxycinnamaldehydes 109 with 4-hydroxycoumarins 1. Mannich asymmetric addition of cyanocoumarins 39 to isatin imines 112 catalyzed by the amide-phosphonium salt 114. Enantioselective total synthesis of (+)-scuteflorin A (119). Funding The authors gratefully acknowledge FAPESP (grants 2013

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

• to an activated electrophile, e.g., an electron-deficient olefin, generating a zwitterion (i, Scheme 1). In further course, the zwitterion acts as a nucleophile or as a base [1]. The efficiency of the formation of this β-phosphonium α-carbanionic species depends on the nucleophilicity of the

• formed by the conjugate addition of the phosphine to the Michael acceptor, is believed to be protonated by the alcohol forming the actual catalytically active species namely ion pair ii, consisting of a phosphonium cation and an alkoxide. The alkoxide in ii then reacts with another electrophile

• generating the ion pair iii. In the final step, the α-carbanionic species in iii gets protonated by an alcohol generating the oxa-Michael addition product (iv) and regenerating ii (Scheme 1). Additionally, the ion par ii might directly react via a nucleophilic substitution of the phosphonium group by the

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

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• esters 109 and hydroxy esters 110 by using (1H-benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) or (1H-benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate (PyBOP) as activating agents as well (Scheme 18) [33]. The synthetic method was further investigated and

• , DCC/DMAP, DCC/1-hydroxybenzotriazole (HOBt), bromotris(dimethylamino)phosphonium hexafluorophosphate (BroP), or O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HBTU) and by 31P NMR analysis. The results indicated that the intermediates, benzotriazolyl phosphonates, were more

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

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

• powerful synthetic tools. Keywords: halomethylcoumarin; Morita–Baylis–Hillman adducts; organocatalyst; phosphonium salt; triazolation; Introduction The presence of versatile functional groups in close proximity classifies Morita–Baylis–Hillman adducts as privileged key scaffolds for synthetic organic

• developing a one-pot synthetic strategy will be worthwhile for pharmacologically important triazoles, such as isavuconazole, tazobactam, and ravuconazole [35]. Results and Discussion Initially, phosphonium salts were barely utilised or exploited in synthetic transformations. Later, in 2014, several organic

• transformations employed quaternary phosphonium salts as favourable catalysts [36]. Their synthetic utility was not only confined to catalysis, but they were also used as intermediates for the synthesis of 1H-indazoles [37], as promoters for stereoselective rearrangements [38], and as temporary protectors of O,P