Synthesis of the 3’-O-sulfated TF antigen with a TEG-N₃ linker for glycodendrimersomes preparation to study lectin binding

• Mark Reihill,
• Hanyue Ma,
• Dennis Bengtsson and
• Stefan Oscarson

Beilstein J. Org. Chem. 2024, 20, 173–180, doi:10.3762/bjoc.20.17

• 1 have recently been reported, one using an enzymatic approach and a commercial α-TEG-N3 GalNAc acceptor [9] and one using glycosyl bromide donors and silver salt-promoted glycosylations [10]. Results and Discussion To introduce the 2-[2-(2-chloroethoxy)ethoxy]ethyl (TEG-Cl) spacer both a Fischer

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group

• Chuanhua Qu,
• Run Huang,
• Yong Li,
• Tong Liu,
• Yuan Chen and
• Guiting Song

Beilstein J. Org. Chem. 2021, 17, 2822–2831, doi:10.3762/bjoc.17.193

• reaction without adding bases, and unexpectedly found Ag salts could catalyze the 1,6-conjugate addition of TosMIC (2a) and p-QM 1a to provide aryl(phenol)methane isonitrile 4a under base-free conditions (Table 1, entries 6–8). When the silver salt was removed from the reaction conditions, the reaction did

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• -annulation of (E)-2-en-4-ynyl azides 1 was considered to involve 6-endo-dig cyclization to give a corresponding N-N2-substituted 1,2-dihydropyridine silver salt 5. This was protonated by TFA and the following species neutralized by base to provide a final 3,6-disubstituted pyridine product 2 (Scheme 2

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

• changing the previously optimized mild reaction conditions (Scheme 6). Only traces of 10 were observed in the absence of one of the metal salts; this excluded the participation of the silver salt in the olefin activation but highlighted its usual role in the activation of the gold catalyst, namely halide

• addition products 10 and 12 (Scheme 7A). In both cases, a low diastereoselective control was observed. Control experiments revealed that, under these reaction conditions, the hydroalkylation was reversible (Scheme 7B), indicating the participation of the silver salt in the C(sp3)–C(sp3)-bond cleavage

• cascade aza-Michael addition/olefin hydroalkylation reaction between N-tosylallylamines and α,β-unsaturated ketones using a catalytic system of a gold(I) complex and a silver salt [45]. The spiro compound 25, which was obtained in moderate yield and with poor diastereoselectivity after a 20 h reaction

Pentannulation of N-heterocycles by a tandem gold-catalyzed [3,3]-rearrangement/Nazarov reaction of propargyl ester derivatives: a computational study on the crucial role of the nitrogen atom

• Giovanna Zanella,
• Martina Petrović,
• Dina Scarpi,
• Ernesto G. Occhiato and
• Enrique Gómez-Bengoa

Beilstein J. Org. Chem. 2020, 16, 3059–3068, doi:10.3762/bjoc.16.255

• on the proton abstraction pathway. Several possible bases exist in the reaction medium, such as the counterion in the gold(I) salt, the anion participating in the silver salt coadditives, or water. In analogy to our previous work [16], we initially modelled the deprotonation step with the triflate

• AgOTf as the silver salt). Under both conditions, the reaction of 14 led to the formation of the cyclopentenone 15 in a lower yield (51% and 66%, respectively), and in comparison to the gold(I)-catalyzed reaction of the enynyl acetates 1, it was much slower with both catalytic systems (6–16 h vs 1.5–2 h

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

• experimental parameters such as solvent, concentration, temperature, catalyst and silver salt. Under standard reaction conditions, no reaction was observed in the absence of a silver salt, and the best results were obtained in the presence of AgOTf (20 mol %), giving the corresponding gem-difluorinated

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

• bulkier silver salt favored a mono-coordination on each binding site. Silver(I) complexes in solution Surprisingly, several batches of each complex 1a–d were compared by 1H NMR (CDCl3, 2 mM) (see Supporting Information File 1, Figure S9) and revealed slight variations in the chemical shifts that might

• : To a solution of ligand 1 (15 mg, 0.0355 mmol) in anhydrous CH2Cl2 (1 mL) was added the corresponding silver salt (0.0355 mmol, 1.0 equiv) under argon atmosphere at room temperature. The mixture was stirred for 4 h. The clear solution was concentrated to ca. 0.3 mL and diethyl ether (2.0 mL) was

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• Heck cyclization reaction between the substituted alkyne and aryl bromide in 133 takes place to form a cyclic palladium intermediate 134 with E-configuration, resulting from a syn-addition mechanism of this step. The addition of a silver salt reduces the probability of isomerization of the double bond

Cobalt-catalyzed peri-selective alkoxylation of 1-naphthylamine derivatives

• Jiao-Na Han,
• Cong Du,
• Xinju Zhu,
• Zheng-Long Wang,
• Yue Zhu,
• Zhao-Yang Chu,
• Jun-Long Niu and
• Mao-Ping Song

Beilstein J. Org. Chem. 2018, 14, 2090–2097, doi:10.3762/bjoc.14.183

• previous literature [30][31][46][47], a plausible reaction mechanism for cobalt-catalyzed alkoxylation was proposed. As shown in Scheme 4, initially, CoIIX2 could be oxidized to CoIIIX2OR in the presence of a silver salt and an alcohol. Based on the experiments and the density functional theory

Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis

• Yue Pan,
• Kunfang Jia,
• Yali Chen and
• Yiyun Chen

Beilstein J. Org. Chem. 2018, 14, 1215–1221, doi:10.3762/bjoc.14.103

• group first used alkynylbenziodoxoles for decarboxylative radical alkynylation under silver salt and persulfate conditions [19]. In 2014, the Chen group discovered that alkynylbenziodoxoles (BI-alkyne) readily participated in photoredox catalysis as the radical alkynylation reagent [20], after which

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

• . More specifically, gold complex AuCl(PPh3) is not usually considered an alkyne hydration catalyst itself, but turns into a catalytically active gold(I) cation after activation with silver salt or Lewis acid [31][32][33][34]. Under the forcing microwave reaction conditions in aqueous methanol

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• using silver nitrate in acetonitrile. Unfortunately in contrast to previous successful ‘halide for nitrate’ transformations no reaction was observed with mesylate rac-71 even after extended reaction times. Repeating the reaction but substituting the silver salt for tetra-n-butylammonium nitrate TLC

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

• ”), there was a noticeable drop in the extent of conversion. In addition, lower loadings of HBF4, silver salt, or the palladium catalyst also gave inferior results. In the case of C–H activation/Suzuki–Miyaura coupling reactions, the commercially available, pre-formed cationic Pd(II) catalyst [Pd(MeCN)4

• formed earlier in water (vide supra), but as seen previously in the corresponding Suzuki–Miyaura reactions, a switch to EtOAc obviated the need for a silver salt. In the presence of BQ and HBF4, the reaction of 1g and acrylate 4 was efficiently catalyzed by Pd(OAc)2 (Figure 5, runs 3 and 4). Lower

• formation. On the other hand, the reaction in the presence of both silver salt and excess of HBF4 gave the corresponding product in 342% yield relative to palladium (TON = 3.4) (Scheme 19). Based on these results, the proposed roles of silver and acid are shown in Scheme 21. After the coupling of the

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• fully recovered. Gold N-heterocyclic carbene complexes, in conjunction with a silver salt, were found to efficiently catalyze different types of reactions [67][68][69]. Therefore, 15 was reacted with [(NHC)AuCl] complex in the presence of AgOTf as the cocatalyst in chloroform. Beside the expected

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• leads to formaldehyde and ammonia, so that in the presence of silver salt the well-known silver mirror reaction could take place, thus justifying the need of at least one equiv of AgNO3. A silver supramolecular complex was proposed by Sun and co-workers as an efficient catalyst for A3-coupling reactions

• bond toward the nucleophile. A role of the silver salt as Lewis acid in the condensation step between amine and carbonyl group has never been claimed even though it could be plausible [52]. This chemistry has been exhaustively evaluated by Wu’s group, whose main interest was the development of new MCRs

• between isoquinolinium-2-ylamide 43 and keteneimine 57 [79], silver salt plays the usual role of a π-philic catalyst, whereas ketene imine 57 is generated by a well-known procedure involving a copper(I)-catalyzed azide–alkyne [3 + 2] cycloaddition (CuAAC) giving rise to 5-cuprated triazole intermediate 56

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• 1,10-phenanthroline and KF respectively [73]. In addition to activating the silyl group of the trifluoromethylating agent, the silver salt also acts as a stabilizer for the CF3− species and prevents its self-decomposition (Figure 4). As a result, the more economical TMSCF3 can be employed, and good

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• diastereoisomers with high enantioselectivities (84–95% ee) [81]. Optimal conditions for the enantioselective variant of the process involved the use of the chiral gold complex Au5 (3.8 mol %), derived from MeO-DTBM-Biphep, in combination with AgOTf. The requirement of equimolar amounts of the silver salt and the

Gold-catalyzed glycosidation for the synthesis of trisaccharides by applying the armed–disarmed strategy

• Abhijeet K. Kayastha and
• Srinivas Hotha

Beilstein J. Org. Chem. 2013, 9, 2147–2155, doi:10.3762/bjoc.9.252

• bond along with side reactions like benzyl deprotection. These observations were then successfully applied for PMB deprotection and one-pot glycosidation. Subsequent experiments proved the significance of the alkyne moiety. It was also observed that the addition of the silver salt AgSbF6 during the

Gold(I)-catalysed one-pot synthesis of chromans using allylic alcohols and phenols

• Eloi Coutant,
• Paul C. Young,
• Graeme Barker and
• Ai-Lan Lee

Beilstein J. Org. Chem. 2013, 9, 1797–1806, doi:10.3762/bjoc.9.209

• , entries 8–10). Firstly, no reaction is observed in the absence of a catalyst (Table 1, entry 8). The Brønsted acid catalyst HNTf2 does form chroman 8, but in a poorer isolated yield (21%, Table 1, entry 9) and the silver salt [76] AgNTf2 as a catalyst does not provide any 8, yielding only 9 and 10 (Table

Synthesis of phenanthridines via palladium-catalyzed picolinamide-directed sequential C–H functionalization

• Ryan Pearson,
• Shuyu Zhang,
• Gang He,
• Nicola Edwards and
• Gong Chen

Beilstein J. Org. Chem. 2013, 9, 891–899, doi:10.3762/bjoc.9.102

• desired arylated product 3 in good yield (Table 1, entry 1). This method, however, required the use of expensive silver salt as an additive and high reaction temperature (150 °C). We next sought to replace the silver salts with cheaper reagents and lower the reaction temperature [12]. Not surprisingly

Antifreeze glycopeptide diastereomers

• Lilly Nagel,
• Carsten Budke,
• Axel Dreyer,
• Thomas Koop and
• Norbert Sewald

Beilstein J. Org. Chem. 2012, 8, 1657–1667, doi:10.3762/bjoc.8.190

• silver salt promoter AgClO4 (0.25 equiv) was added at room temperature and stirring was continued for 30 min. Subsequently, the 2-azido-2-deoxy-3,4,6-tri-O-acetyl-α-D-galactopyranosyl chloride (1.5 equiv) was added dissolved in abs toluene (30–40 mL) and methylene chloride (30–40 mL), and the solution

Efficient gold(I)/silver(I)-cocatalyzed cascade intermolecular N-Michael addition/intramolecular hydroalkylation of unactivated alkenes with α-ketones

• Ya-Ping Xiao,
• Xin-Yuan Liu and
• Chi-Ming Che

Beilstein J. Org. Chem. 2011, 7, 1100–1107, doi:10.3762/bjoc.7.126

• amount of silver salt may have remained in the reaction system when the mol ratio of silver salt to gold complex was 1:1, see [45]). Upon further increase of the AgOTf loading to 10 mol %, the corresponding product 3a was formed in 58% yield with a diastereomeric ratio of 5.4:1 (Table 1, entry 3) [46

• mixture did not have a noticeable effect on the yield of 3a (Table 1, entries 8–11). To identify further the optimal reaction conditions for the gold(I)/silver(I)-cocatalyzed cascade reaction, a number of dual-metal catalyst systems, composed of 15 mol % of silver salt with 5 mol % of gold(I) complex in

• different organic solvents, were tested in the reaction of phenyl vinyl ketone (1a) with 1.5 equiv of N-tosylallylamine (2a) (Table 2). AgClO4 was found to be the best silver salt for this reaction (Table 2, entries 1–5). A panel of Au(I) complexes with different ancillary ligands was also screened for

Chiral gold(I) vs chiral silver complexes as catalysts for the enantioselective synthesis of the second generation GSK-hepatitis C virus inhibitor

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

Beilstein J. Org. Chem. 2011, 7, 988–996, doi:10.3762/bjoc.7.111

• [36] and, finally, underwent anion interchange in the presence of the corresponding silver salt. The precipitate was filtered through a celite pad and used without any other additional treatment. All of the reactions were performed at room temperature, employing a 5 mol % of both catalyst and base

• represented in Scheme 2. The chiral ligand (Sa)-BINAP (13) was also tested in the standard reaction to access key molecule endo-5b (Scheme 3). AgClO4 was found to be the most appropriate silver salt to achieve the highest enantioselectivity (88% ee) compared to the results obtained when other silver salts