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

Vicinal difunctionalization of alkenes by four-component radical cascade reaction of xanthogenates, alkenes, CO, and sulfonyl oxime ethers

• Shuhei Sumino,
• Takahide Fukuyama,
• Mika Sasano,
• Ilhyong Ryu,
• Antoine Jacquet,
• Frédéric Robert and
• Yannick Landais

Beilstein J. Org. Chem. 2019, 15, 1822–1828, doi:10.3762/bjoc.15.176

• , alkenes, CO, and sulfonyl oxime ethers, can proceed under radical mediated conditions, using hexabutylditin as a radical chain carrier, to give the corresponding keto-oximes in moderate yields. A variety of functional groups are tolerated under the high CO pressure and temperature conditions. Among

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• thiyl-radical-mediated reactions have been extensively investigated for the preparation of carbohydrate derivatives [20] and some dithioether phospholipid and glycolipid analogues [21][22], no examples were reported for the synthesis of n-alkyl thioglycosides by using thiol–ene coupling [18][19]. In

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• synthesis of 1-naphthaldehydes 25 under mild conditions via a radical-mediated ring-opening and intramolecular cyclization of MCPs 23 with organic selenium reagents 24 (Scheme 8) [59]. In this reaction, the MCPs with electron-withdrawing groups gave lower yields than that with electron-donating groups

• radical intermediate 76. The intermediate 77, produced by the intramolecular cyclization of intermediate 76, reactes with diphenyl diselenide 73 to form the target product 74 via homolytic substitution (SH). In 2013, Ryu and co-workers developed the bromine radical-mediated ring-opening and alkylation of

• (path IV in Scheme 17). In 2016, Xu’s group exploited the fluoroalkyl (RF) radical-mediated ring-opening of MCPs 1 for the synthesis of fluorinated homoallylic compounds (80 and 81, Scheme 18) [96]. In this reaction system, the radical reaction of MCPs 1 with RF-X (X = Br, I) furnished homoallylic

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• electrochemical reduction. In addition, the corrin-ring of the B12 derivatives is tolerant to free radicals, as described above. Thus, alkylated complexes have been used for radical-mediated organic synthesis such as halide coupling, alkene coupling, and addition to double bonds [7][26][27]. In particular, the Co

• , and Irdfppy system was used for radical-mediated isomerization reactions. Visible-light irradiation of diethyl 2-bromomethyl-2-phenylmalonate produced the phenyl-migrated product (Scheme 10) [104]. The product distribution highly depended on the solvents. The yield of phenyl-migrated products relative

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• -radical mediated “click” process with diverse applications in small molecule and polymer synthesis and has been reviewed [74][75][76]. The importance of the thiol-ene reaction in the synthesis of β-hydroxy sulfides is exemplified by the work of Scanlan and co-workers as shown in Scheme 41 [77][78

Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of vicinal-dichlorides and chlorodienes

• Zhensheng Zhao and
• Graham K. Murphy

Beilstein J. Org. Chem. 2018, 14, 796–802, doi:10.3762/bjoc.14.67

• pathways. For example, Liu and co-workers used Togni’s benziodoxolone reagent [35] in a radical-mediated vicinal 2,3-difunctionalization of allenes, which proceeded via CF3-radical adduct A (Scheme 1a) [36]. In contrast, Muñiz reported that with PhI(NTs2)2, an oxidative amination occurred via cation B

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• [27], with R-CH=O/(n-Bu)4NBr (TBAB, cat.)/K2S2O8 at 90 °C [28], with ArSO2H/Eosin Y(cat.)/tert-butyl hydrogen peroxide (TBHP) at rt [29], and with ArSO2NHNH2/n-Bu4NI(cat.)/TBHP at 80 °C [30]. In addition, the formation of coumarins via the bromine-radical-mediated reaction of aryl 2-alkynoates with

• TBAB/K2S2O8 at 90 °C [31], the cyanomethyl-radical-mediated reaction of aryl 2-alkynoates with tert-butyl peroxybenzoate (TBPB)/acetonitrile at 130 °C [32], the sunlight-promoted reaction of aryl 2-alkynoates with N-iodosuccinimide (NIS) at rt [33], and the visible-light-mediated reaction of aryl 2

• the formed phenyl 3-phenyl-2-propynoate (2Aa) with TBAB and Na2S2O8 in a mixture of DCE and water is a radical-mediated bromocyclization reaction. X-ray crystallographic analysis of 3-bromo-7-chloro-4-phenylcoumarin (3Da), which was formed by the subsequent treatment of 3-phenyl-2-propynoic acid (1a

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• , replacing the chiral phosphoric acid with diphenyl phosphate (Scheme 14) [20]. Liu’s research group was interested as well in 1,2-difunctionalisation of unactivated alkenes. In this context, they developed two distinct approaches allowing to perform radical-mediated 1,2-formyl- [21] or 1,2

Synthesis of three-dimensional porous hyper-crosslinked polymers via thiol–yne reaction

• Mathias Lang,
• Alexandra Schade and
• Stefan Bräse

Beilstein J. Org. Chem. 2016, 12, 2570–2576, doi:10.3762/bjoc.12.252

• metal-free reaction conditions, high yields and easy purification. Results and Discussion The first network shown here was synthesized by crosslinking the two tetrahedral tetraphenylmethane core structures 1 and 2 via the radical-mediated thiol–yne reaction using AIBN as initiator. The second network

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• heterocyclisation to form thiazolines or oxazolines, and radical-mediated reactions between unactivated carbons. Future prospects for RiPP pathway discovery and characterisation will also be highlighted. Keywords: biosynthesis; cyclisation; enzymes; peptides; RiPPs; Introduction Nature employs a number of routes

Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp² C–H and sp³ C–H bonds

• Nivesh Kumar,
• Santanu Ghosh,
• Subhajit Bhunia and
• Alakesh Bisai

Beilstein J. Org. Chem. 2016, 12, 1153–1169, doi:10.3762/bjoc.12.111

• -arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for this reaction. Keywords: C−H functionalization; intramolecular dehydrogenative coupling (IDC); iodine; N-iodosuccinimide; oxidants; 2-oxindoles; Introduction The

• skeleton such as calycanthine (22c) (Scheme 5) [78]. In all the cases, IDC was feasible with substrates having substituents at the carbon atom α- to the amides. This gave a clue for a radical-mediated process where a single electron transfer (SET) mechanism might be operating. A tentative mechanism has

• showed that it is important to have a tertiary carbon α- to the amide for the process to be radical mediated [38][39]. Also, it is well evident from literature that the oxidation processes using Mn(OAc)3 as oxidant follow a radical pathway [82][83][84][85][86]. In fact, the reaction of 3a also afforded 2

Catalytic asymmetric formal synthesis of beraprost

• Yusuke Kobayashi,
• Ryuta Kuramoto and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2015, 11, 2654–2660, doi:10.3762/bjoc.11.285

• Our retrosynthetic analysis for 2 is shown in Scheme 1, with the derivatization of 2 to beraprost (1) having already been reported. We planned to introduce the ester side chain on the aromatic ring at a later stage, utilizing radical-mediated reactions with acrylate [22] when the functional group (X

Radical-mediated dehydrative preparation of cyclic imides using (NH₄)₂S₂O₈–DMSO: application to the synthesis of vernakalant

• Dnyaneshwar N. Garad,
• Subhash D. Tanpure and
• Santosh B. Mhaske

Beilstein J. Org. Chem. 2015, 11, 1008–1016, doi:10.3762/bjoc.11.113

• for a practical synthesis of vernakalant. Keywords: APS-DMSO; imides; practical synthesis; radical-mediated; vernakalant; Introduction Cyclic imides are privileged pharmacophores and important building blocks for the synthesis of natural products, drugs, agrochemicals, advanced materials and

Multicomponent versus domino reactions: One-pot free-radical synthesis of β-amino-ethers and β-amino-alcohols

• Bianca Rossi,
• Nadia Pastori,
• Simona Prosperini and
• Carlo Punta

Beilstein J. Org. Chem. 2015, 11, 66–73, doi:10.3762/bjoc.11.10

• ]. Likewise, the development of radical-mediated, C–C bond-forming transformations has also attracted increasing interest. These protocols usually afford good selectivity, are highly compatible with common functional groups, and often require mild operative conditions [8][9][10][11][12]. During the course of

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

Efficient routes toward the synthesis of the D-rhamno-trisaccharide related to the A-band polysaccharide of Pseudomonas aeruginosa

• Aritra Chaudhury,
• Sajal K. Maity and
• Rina Ghosh

Beilstein J. Org. Chem. 2014, 10, 1488–1494, doi:10.3762/bjoc.10.153

• the A-band polysaccharide of Pseudomonas aeruginosa. One of the key steps involved 6-O-deoxygenation of either partially or fully acylated 4,6-O-benzylidene-1-thiomannopyranoside by radical-mediated redox rearrangement in high yields and regioselectivity. The D-rhamno-thioglycosides so obtained

• -rhamno-trisaccharide. The application of the reported regioselective radical-mediated deoxygenation on 4,6-O-benzylidene D-manno thioglycoside (hitherto unexplored) has potential for ramification in the field of synthesis of oligosaccharides based on 6-deoxy hexoses. Keywords: A-band polysaccharide; D

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

• Nathan J. Gesmundo and
• David A. Nicewicz

Beilstein J. Org. Chem. 2014, 10, 1272–1281, doi:10.3762/bjoc.10.128

• triarylpyrylium salts, as they have excited state reduction potentials in excess of +1.7 V vs SCE (Scheme 2) [20]. In addition, prior work demonstrates that these catalysts are productive in cation radical mediated [4 + 2], [2 + 2], oxygenation, and rearrangement chemistry [21][22]. We also sought to delineate

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• of sustainable radical-mediated chemical processes under very soft irradiation conditions (e.g., household fluorescence or LED bulbs, halogen lamps, sunlight, Xe lamp), e.g., enantioselective alkylation, cycloaddition, etc. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Ruthenium- and iridium-based

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• materials, the chemical mechanism of polymer degradation is by far not fully understood. It has generally been assumed that polymer degradation involves a radical-mediated autoxidation mechanism, which propagates through hydrogen abstraction by an intermediate peroxyl radical ROO•. Although this

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

• Roy T. McBurney and
• John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

• research initiated spiralling interest by synthetic chemists in iminyl radical-mediated preparations. Recently iminyls have been generated from quite a variety of precursors [10][11][12][13][14][15], and their cyclisations onto arenes [16][17][18][19][20][21] and heteroarenes [22][23][24] have attracted

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

• –Hubert condensation [9], radical-mediated reactions [10][11][12][13], metal-catalyzed cross-couplings [14][15][16][17][18], cycloadditions [19], and others [20][21][22]. More recently, methods based on the metal-catalyzed functionalization of carbon–hydrogen (C–H) bonds have also emerged as viable

Bioactive selaginellins from Selaginella tamariscina (Beauv.) Spring

• Chao Yang,
• Yutian Shao,
• Kang Li and
• Wujiong Xia

Beilstein J. Org. Chem. 2012, 8, 1884–1889, doi:10.3762/bjoc.8.217

• selaginellin M (2) and selaginellin (3), with IC50 equal to 28.5 and 33.1 μM, respectively. Over the past few decades, considerable biochemical, physiological and pharmacological evidence has accumulated to support the hypothesis that free-radical-mediated oxidative processes are implicated in various human

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• alcohol 41 opens up a route to quinolizidine alkaloids containing C-1 methyl substituents (provided, of course, that we can find a better method for deoxygenation, probably by radical-mediated reaction). In addition, alkyl homologues at C-1 should be accessible; one could, for example, replace the alcohol