Advances in radical peroxidation with hydroperoxides

• Oleg V. Bityukov,
• Pavel Yu. Serdyuchenko,
• Andrey S. Kirillov,
• Gennady I. Nikishin,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2024, 20, 2959–3006, doi:10.3762/bjoc.20.249

• tert-butylperoxy radical В. Fe(acac)3-catalyzed oxidation of benzyl, allyl and propargyl ethers 78 with TBHP led to the formation of tert-butylperoxyacetals 79 (Scheme 28) [75]. Probably, in the first step TBHP oxidizes Fe(II) to Fe(III) with the formation of tert-butoxy radical A. Then the second

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• ·H2O, FeSO4, and Fe(acac)3 resulted in inferior chemical yields. Employment of 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) as a radical trapper inhibited the reaction, which proved that a radical process was involved. The reaction was initiated by a single electron transfer (SET) process from the

• imidated product 32. In 2018, an Fe-catalyzed carbosulfenylation and carboselenylation 33 of alkenes with N-(thio/seleno)phthalimides 14 was introduced by Lv and Li (Scheme 17) [54]. The use of Lewis acids, such as AlCl3, ZnCl2, InCl3, Fe(OTf)2 and Fe(acac)3 was not beneficial. However, BF3·OEt2, SnCl4

• , CoCl2, NiCl2, MnCl2, FeCl2, Fe(acac)3 and copper salts such as Cu(OAc)2, CuBr2, CuBr, CuCl2, and CuCN·2LiCl were evaluated in this coupling reaction, in which Cu(OAc)2 showed highest product yields. Moreover, phthalimides with SCF3, SCN, and SePh groups also worked well in this approach. Because of the

Total synthesis of insect sex pheromones: recent improvements based on iron-mediated cross-coupling chemistry

• Eric Gayon,
• Guillaume Lefèvre,
• Olivier Guerret,
• Adrien Tintar and
• Pablo Chourreu

Beilstein J. Org. Chem. 2023, 19, 158–166, doi:10.3762/bjoc.19.15

• , the presence of NMP is actually detrimental. Indeed, for the cross coupling reaction of octylmagnesium chloride with 1-butadienyl phosphate in THF at −20°C in the presence of 1% Fe(acac)3 and 9 equivalents of NMP, the resulting 1,3-dodecadiene cross-coupling product was only obtained with a 54% yield

• -coupling reactions between alkylmanganese nucleophiles AlkylMnX and thioesters RC(O)SEt using Fe(acac)3 as catalyst could act as a ligand to on-cycle organoiron(II) intermediates (Table 2, entry 3) [39]. This behaviour opens the door to interesting synthetic perspectives, since it suggests that leaving

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• in 60% yield, when 147 was treated with PhSiH3 in the presence of Fe(acac)3. Notably, the reaction provided a diastereoselectivity of 3:1 for the formation of the C20-stereocenter and exclusive formation of the C3-center. Key to this success is the low level of Fe(III)–H generation, thus minimizing

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• of Fe(acac)3 and a ligand (Scheme 10) [27]. The optimized reaction of phenylacetylene with 1-iodobenzene comprised 10 mol % of Fe(acac)3, 20 mol % of 2,2’-bipyridyl and 2 equiv of Cs2CO3 in toluene at 135 °C for 42 h. By using Fe(acac)3 as catalyst and 2,2’-bipyridine (25) as the ligand the best

• alkynes with Fe(acac)3/2,2-bipyridine catalyst. Sonogashira cross-coupling of terminal alkynes with aryl iodides in the presence of Fe powder/ PPh3/CuI catalyst. α-Fe2O3 nanoparticles-catalyzed coupling of phenylacetylene with aryl iodides. Sonogashira cross-coupling reaction between phenylacetylene and 4

• )-catalyzed Sonogashira–Hagihara coupling reaction. Sonogashira coupling using the Fe(II)(bdmd) catalyst in DMF/1,4-dioxane. Synthesis of 7-azaindoles using Fe(acac)3 as catalyst. Plausible mechanistic pathway for the synthesis of 7-azaindoles. Synthesis of Co@imine-POP catalyst. Sonogashira coupling of

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• co-workers established a Heck/Kumada cross-coupling cascade to construct nitrogen and oxygen-containing cis-heterospirocycles 40 in high yield and diastereoselectivity with inexpensive Fe(acac)3 as the precatalyst (Scheme 8) [73]. Interestingly, this protocol was applicable to substrates bearing

• classically sensitive functionalities like esters and aryl chlorides. Exposure of the iron catalyst to one equivalent of aryl Grignard reagent 2b in the absence of the halide substrate afforded the bimetallic Fe(II) complex FeBr2[Mg(acac)2](THF)2. Using FeBr2[Mg(acac)2](THF)2 in place of Fe(acac)3 in the

• 74. Hydrolysis of the imine affords the final product 69. In 2020, Sun and Liu reported the iminyl cyclization could also be achieved with DMSO as a methyl-radical precursor [88]. In 2017, the Zhu group developed an Fe(acac)3-catalyzed cyanoalkylative dearomatization of N-phenylcinnamamides 75 for

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

• could be conducted in an air atmosphere, and the reaction times were shorter using a combination of Fe(acac)3 and PhSiH3 as the reductor (Mukaiyama-like conditions) in the presence of an alkoxide source (Scheme 21) [79]. Under these conditions, the radical formed after the HAT with unactivated olefins

Cross-coupling of dissimilar ketone enolates via enolonium species to afford non-symmetrical 1,4-diketones

• Keshaba N. Parida,
• Gulab K. Pathe,
• Shimon Maksymenko and
• Alex M. Szpilman

Beilstein J. Org. Chem. 2018, 14, 992–997, doi:10.3762/bjoc.14.84

• involve the coupling of amide enolates with ketone enolates. Baran reported that stoichiometric Cu(2-ethylhexanoate)2 or Fe(acac)3 (2 equiv) are able to selectively oxidize imides, including Evan’s-type chiral imides, to the corresponding radicals. The formed radical then reacts selectively with a ketone

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Viktoriia V. Pakalnis,
• Roman O. Iakovenko and
• Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

• -system (4.56, 4.68 ppm). Attempts to initiate the reaction by UV-irradiation (at 20 or 50 °C) or catalysis by compounds of transition metals (Cu(acac)2, Fe(acac)3, Pd(bzac)2, Rh2(AcO)4, Cu(OTf)2, Pd/C) at 20 or 40 °C failed. Benzene was found to be a solvent of choice, and a 1:1 molar ratio of reagents

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• excellent stereoselectivity, and only trans-isomers are obtained. Keywords: alkenylation; cycloalkanes; decarboxylative; Fe(acac)3; free radical; sp3 C–H bonds; Introduction Direct C–H functionalization has become one of the most useful and attractive tools in organic chemistry because it can construct

• ][68]. Our group was surprised to find that low-cost Fe(acac)3 could catalyze the direct alkenylation of cyclohexane sp3 C–H bonds by decarboxylative couplings with high efficiency. Results and Discussion We initiated our investigation by reacting cinnamic acid (1a, 0.3 mmol) with cyclohexane (2a, 2 mL

• , Fe2O3 and Fe3O4 tested (Table 1, entries 4–8). Application of other oxidants such as K2S2O8, H2O2 (30% aqueous solution) or TBPB did not afford any improvements (Table 1, entries 9–11). A decreased loading of Fe(acac)3 to 10 mol % or an increased amount of DTBP to 5.0 equiv and a lower temperature (110