Ligand-dependent stereoselective Suzuki–Miyaura cross-coupling reactions of β-enamido triflates

• Tomáš Chvojka,
• Athanasios Markos,
• Svatava Voltrová,
• Radek Pohl and
• Petr Beier

Beilstein J. Org. Chem. 2021, 17, 2657–2662, doi:10.3762/bjoc.17.179

• -diaryl-substituted enamides is observed. Thus, the method provides synthetic access to both isomers of the target enamides from (Z)-β-enamido triflates. Keywords: enamides; isomerization; Suzuki–Miyaura coupling; vinyl triflates; Introduction Enamides are substrates of high value in organic synthesis

• study. Substituted phenylboronic acids and vinyl triflates led to the formation of enamides 2 with high stereoselectivity and in good to high NMR yields (Scheme 2). However, isolated yields were found to be lower due to the decomposition of the formed enamides 2 during column chromatography on silica

• was ruled out because the treatment of 2ca under conditions leading to inversion of the configuration did not affect the ratio between the resulting enamides. Conclusion In conclusion, the stereoselective outcome of the Suzuki cross-coupling of vinyl triflates 1 with arylboronic acids was found to be

Synthesis of 5-arylacetylenyl-1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

• Andrey I. Puzanov,
• Dmitry S. Ryabukhin,
• Anna S. Zalivatskaya,
• Dmitriy N. Zakusilo,
• Darya S. Mikson,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2021, 17, 2417–2424, doi:10.3762/bjoc.17.158

• bond of these oxadiazoles quantitatively resulted in E/Z-vinyl triflates. The reactions of the cationic intermediates have been studied by DFT calculations and the reaction mechanisms are discussed. Keywords: acetylene-oxadiazoles; Friedel–Crafts reaction; hydroarylation; superelectrophilic activation

• vinyl triflates 4a–c with a predominant formation of Z-isomers as product of an anti-addition of TfOH to the acetylene bond (Scheme 3). E/Z-Stereochemistry of compounds 4a–c was determined by H,F-NOESY correlation between vinyl proton (>C=CH–) and the CF3 group from the TfO substituent (see Supporting

• hydroarylation of the acetylene bond in the reaction with arenes or vinyl triflates in reaction with TfOH without arenes. Synthesis of 5–arylethynyl-3-aryl-1,2,4-oxadiazoles 3a–e. Plausible reaction mechanism for transformations of 5-acetylenyl-1,2,4-oxadiazoles 3 in Brønsted superacids. Quantitative formation

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• trifluoromethylation of vinyl triflates and nonaflates (Scheme 65). A variety of trifluoromethylated cyclohexenes were obtained using a catalyst system, which was composed of Pd(dba)2 or [(allyl)PdCl]2 and the monodentate biaryl phosphine ligand t-BuXPhos. Also, TMSCF3 and KF were more suitable to the

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• (see discussion on NMR of cations B, Table 1). Under the heating in TfOH at 100 °C for 0.5 h, these allenes afforded (arylsulfonyl)acetones 6a,b, which may be formed under the hydrolysis of the formed vinyl triflates F (Scheme 6). Finally, in this study, we carried out reactions of (arylsulfinyl

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• carboxylation of vinyl triflates 3. Co-catalyzed carboxylation of a sterically hindered aryl triflate 5. Optimization of the Co-catalyzed carboxylation of 7a. Scope of the reductive carboxylation of α,β-unsaturated nitriles 7. Scope of the carboxylation of α,β-unsaturated carboxamides 9. Optimization of the Co

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• ][13]. Vinyl halides are relatively less reactive alkylating agents. However, the use of readily available vinyl triflates 5 for the alkylation of triphenylphosphine in THF solution in the presence of a catalytic amount of (Ph3P)4Pd (1–3 mol %) gave the expected vinylphosphonium salts in a yield of 62

• subsequent isomerization of intermediate allylphosphonium salts. Alkylation of triphenylphosphine with vinyl triflates in the presence of (Ph3P)4Pd. Mechanism of alkylation of triphenylphosphine with vinyl triflates in the presence of (Ph3P)4Pd as catalyst. β-Elimination of phenol from β

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• palladium [152] and, in some cases, nickel or copper. The phosphinating agents may comprise primary and secondary phosphines, silylphosphines [153] or phosphine–borane complexes. The vinylic coupling partner mostly consists of alkenylhalides or alkenyltriflates. Vinyl triflates are used more since they can

• al. have reported the coupling of secondary phosphine boranes with unactivated vinyl triflates (Table 7 and Table 8) [159]. Cyclic and acyclic vinyl triflates (78 and 80a) were reacted with diaryl-, dialkyl- and alkylarylphosphine–borane complexes, 13f and 13g respectively. The reactions were

• performed with a palladium catalyst in the presence of a weak base. Sometimes microwave irradiation was used to shorten the reaction time. Gilbertson et al. have converted a series of vinyl triflates 80b into the corresponding vinyl phosphine boranes 81b through palladium catalysis with HPPh2 (Table 9) [160

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

• system to convert cyclic vinyl triflates or nonaflates to their trifluoromethylated equivalents (Table 4) [66]. Ruppert’s reagent was used as the CF3– precursor in a combination with potassium fluoride as an activator for the reaction with vinyl triflates, while TESCF3 and rubidium fluoride gave better

Toward an integrated route to the vernonia allenes and related sesquiterpenoids

• Da Xu,
• Michael A. Drahl and
• Lawrence J. Williams

Beilstein J. Org. Chem. 2011, 7, 937–943, doi:10.3762/bjoc.7.104

• -suited for access to the vernonia targets and related compounds [15]. The method relies on suitably functionalized vinyl triflates [39][40][41]. In general, C–C fragmentation reactions appear to be sensitive to the precise structure of the cyclic system involved, and small, apparently minor, structural