Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• oxygen of air (Scheme 36) [126]. The peroxide initially formed in the reaction was reduced by treatment with a saturated Na2S2O4 solution. The formation of peroxide was confirmed by a control experiment in which the hydroperoxide 113b’ was isolated when the treatment of the reaction mixture with sodium

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• superoxide radical anion by a reductive quenching and the rearrangement of the hydroperoxide intermediate [41]. The heterogeneous protocol using MOF porphyrins was significantly faster than the corresponding homogeneous photocatalysis, which was attributed to higher photostability of the porphyrins as MOF

• -α-hydroxy-β-keto esters in 81–93% yields and 39–75% ee (Scheme 41). The mechanism of this reaction involves the attack of the enolate paired with the chiral counter ion PTC to the singlet oxygen electrophile to give the hydroperoxide intermediate, which is converted to α-hydroxy-β-keto esters

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

• excellent yields, with the hydroperoxide functional group acting as a precursor of an alkoxy radical to control site-selective carbon-centered radical formation. Allylic fluorination: In 2011, the group of Nguyen [92] developed the nucleophilic fluorination of allylic trichloroacetimidates, as shown in

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• -iodo-4-nitrobenzene (3) [68]. The TEMPO moiety was introduced at the benzylic position of 5a and 5b using the copper-catalyzed radical reaction in the presence of tert-butyl hydroperoxide (TBHP) to afford 2a and 2b in 38% and 52% yield, respectively [69]. The caged TEMPOs 2a and 2b were thermally

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• reported on the reactivity of oxenoids [74][75][76][77], indicating that the reaction of a nucleophile with oxenoid proceeds through an SN2 process [74]. Following the carbocupration of cyclopropene 3 into cyclopropylcopper species, the subsequent oxidation with the amphiphilic lithiated hydroperoxide t

• stirred until TLC shows complete consumption of the starting material (eluent hexane/EtOAc 9:1, ca. 30 min). The oxenoid was prepared in a different flask by slowly adding n-BuLi (1.2 equiv) to a solution of tert-butyl hydroperoxide (2 equiv) in THF (5 mL/2 mmol) at −80 °C. After 30 min at −80 °C, the

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• by Ishii and co-workers on the aerobic oxidation of cumene in acetic acid using catalytic NHPI and cobalt(II), resulted in a mixture of 2-phenyl-2-propanol, acetophenone, and phenol [60][61]. This lack of selectivity in the product was related in part to the propensity of the cumene hydroperoxide

Synthesis and biological investigation of (+)-3-hydroxymethylartemisinin

• Toni Smeilus,
• Farnoush Mousavizadeh,
• Johannes Krieger,
• Xingzhao Tu,
• Marcel Kaiser and
• Athanassios Giannis

Beilstein J. Org. Chem. 2019, 15, 567–570, doi:10.3762/bjoc.15.51

• containing methylene blue as photosensitizer was exposed to sunlight and oxygen. The treatment of the resulting intermediate hydroperoxide with a small amount of trifluoroacetic acid as previously described [17][18], afforded in the frame of a Hock cleavage (+)-3-hydroxymethyl-9-desmethylartemisinin (16) in

6’-Fluoro[4.3.0]bicyclo nucleic acid: synthesis, biophysical properties and molecular dynamics simulations

• Sibylle Frei,
• Andrei Istrate and
• Christian J. Leumann

Beilstein J. Org. Chem. 2018, 14, 3088–3097, doi:10.3762/bjoc.14.288

• phosphoramidite building blocks into oligonucleotides was achieved with tert-butyl hydroperoxide as oxidation agent. Thermal melting experiments of the modified duplexes disclosed a destabilizing effect versus DNA and RNA complements, but with a lesser degree of destabilization versus complementary DNA (ΔTm/mod

• -butyl hydroperoxide (TBHP), which previously has been successfully applied for the synthesis of iso-tricyclo-T (iso-tc-T) or bcen-T containing oligonucleotides [61]. Indeed, under these conditions high coupling yields (>98%) of ON3–7 were obtained and the absence of the 5’-phosphorylated fragment was

• cyclopropane ring opening which proceeded in high yields. The two phosphoramidite building blocks were successfully incorporated into oligonucleotides by automated solid-phase DNA synthesis with tert-butyl hydroperoxide as the oxidation agent. The CD spectra of the 6’F-bc4,3-T or -C-modified oligonucleotides

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• suitable reagent, a “chemical trigger” [69]. In the case of the RCM/allylic oxidation sequence tert-butyl hydroperoxide is added after completion of the metathesis reaction, which most likely induces a conversion of the metathesis active Ru–carbene species to a Ru(IV)–oxo species. The latter are known to

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• hydroperoxide in dichloromethane at room temperature for 2 h, the respective diazo aromatic compound 6 could be obtained in 50% yield (Scheme 5). As can be seen, the reaction proceeded smoothly allowing formation of the new N=N bond without cleavage of the C–Se bond under the oxidant media and the presence of

Synthesis of aryl sulfides via radical–radical cross coupling of electron-rich arenes using visible light photoredox catalysis

• Amrita Das,
• Mitasree Maity,
• Simon Malcherek,
• Burkhard König and
• Julia Rehbein

Beilstein J. Org. Chem. 2018, 14, 2520–2528, doi:10.3762/bjoc.14.228

• very slow when air was used as an oxidant, also it led to various oxidation products of the sulfur and the degradation of the photocatalyst was observed upon irradiation. Therefore, (NH4)2S2O8 was used as terminal oxidant. The addition of tert-butyl hydroperoxide (TBHP) as an oxidant led to degradation

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

• Xiaoshen Ma and
• Seth B. Herzon

Beilstein J. Org. Chem. 2018, 14, 2259–2265, doi:10.3762/bjoc.14.201

• -butyl hydroperoxide (TBHP), and triethylsilane (Et3SiH) constitute an inexpensive, general, and practical reagent combination to initiate a broad range of Markovnikov-selective alkene hydrofunctionalization reactions. These transformations are believed to proceed by cobalt-mediated hydrogen atom

• ligand architectures [21], and often need to be prepared by multistep sequences. Here we report a uniform set of reaction conditions to achieve a broad range of HAT hydrofunctionalization reactions using the simple reagents cobalt acetoacetonate [Co(acac)2], tert-butyl hydroperoxide (TBHP), and

Hypervalent iodine compounds for anti-Markovnikov-type iodo-oxyimidation of vinylarenes

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Mikhail A. Syroeshkin,
• Alexander A. Korlyukov,
• Pavel V. Dorovatovskii,
• Yan V. Zubavichus,
• Gennady I. Nikishin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2018, 14, 2146–2155, doi:10.3762/bjoc.14.188

• the reactions of styrenes with imide-N-oxyl radicals, in which the latter add to the terminal position of the double C=C bond with the formation of stabilized benzyl radicals, which undergo the subsequent functionalization. In the presence of oxygen or tert-butyl hydroperoxide, oxidation proceeds to

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• of the reactions proceed in good yields. The use of tert-butyl hydroperoxide as the oxidant likely prohibits the use of oxidation-sensitive functional groups, such as alkenes or aldehydes. Use of a milder oxidant, e.g., oxygen – seen many times in this review, could help broaden the functional group

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

• single thiol was employed. In a subsequent one pot procedure, addition of tert-butyl hydroperoxide to the reaction mixture afforded β-hydroxy sulfoxide 32 in good yields. In a similar fashion, Su et al. reported first the Ga(OTf)3 catalyzed regio- and stereoselective ring opening of epoxides 23 with

• effect the reaction since in its absence, the addition of hydrogen and –SR across the double bond ensues, yielding the undesired ArCH2CH2SAr according to Markovnikov's rule. 3.2.3 The use of tert-butyl hydroperoxide. Zhou et al. reported the hydrosulfurization of alkenes with thiols for the direct

• synthesis of β-hydroxy sulfides, with a catalytic amount of tert-butyl hydroperoxide (TBHP) as an initiator (Scheme 28) [66]. Even styrenes bearing powerful electron withdrawing groups such as nitriles (CN), trifluoromethyl (CF3) and ester groups (COOCH3) gave the corresponding β-hydroxy sulfides, albeit in

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• % was observed for the 5-fluorinated isatin imine (R = F). Comparable reaction conditions were applied to the addition of cumene hydroperoxide 58 to N-Boc-isatin imines 3 providing the corresponding chiral oxindoles 59 in even higher yields (99%) and enantioselectivities (88–94% ee), as shown in Scheme

• and cumene hydroperoxide to N-Boc-isatin imines. Palladium-catalyzed addition of arylboronic acids to N-tert-butylsulfonylisatin imines.

Volatiles from three genome sequenced fungi from the genus Aspergillus

• Jeroen S. Dickschat,
• Ersin Celik and
• Nelson L. Brock

Beilstein J. Org. Chem. 2018, 14, 900–910, doi:10.3762/bjoc.14.77

• biosynthetic pathway from linoleic acid via its hydroperoxide has been suggested [24][25][26], and if the same biosynthetic steps would proceed from linolenic acid, this would result in the assigned structure of 2 (Scheme 1B). The other compounds identified in the headspace extracts of A. fischeri were all

Mannich base-connected syntheses mediated by ortho-quinone methides

• Petra Barta,
• Ferenc Fülöp and
• István Szatmári

Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43

• )indoles 52. Then, through C-2 cyclization of the indole ring using I2 as catalyst and tert-butyl hydroperoxide as oxidant, chromeno[2,3-b]indoles were isolated in 71–98% yields. In a different reaction pathway, starting from 3-(aminoalkyl)indoles 53 and phenols or naphthols, 3-(α,α-diarylmethyl)indoles 52

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• transformation (Scheme 37). Firstly, the trifluoromethyl radical was generated in situ by the reaction of tert-butyl hydroperoxide with CF3SO2Na in the presence of catalytic amounts of CuI. Next, the addition of the CF3 radical to the electron-rich α-position of the substrates formed the radical species B

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• , trifluoromethyl groups and halides, but iodides led to polymer formation. Li and Wang developed a method for the α-C(sp3)–H thiolation of ethers, using Acridine Red as photosensitizer and tert-butyl hydroperoxide (TBHP) as oxidant (Scheme 38) [73]. They reported that photoexcited Acridine Red performs an energy

• reduction of tert-butyl hydroperoxide (TBHP) to form a reactive tert-butoxyl radical. After hydrogen abstraction from the sulfinic acid and subsequent radical addition to the alkyne derivative, consecutive steps for rearomatization lead to the cyclic coumarin adduct. The authors used various electron

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

•  69) [20], Langlois and co-workers demonstrated that enol acetates 1a–c were converted into the corresponding α-trifluoromethyl ketones upon treatment with CF3SO2Na with tert-butyl hydroperoxide (TBHP) and a catalytic amount of copper(II) triflate (Scheme 1) [21]. The scope was rather narrow and

• aryl and heteroaryl ketones featuring a single enolizable position (Scheme 2) [22]. Notably, it was found that Cu(II) and Cu(I) salts gave similar yields. A radical trifluoromethylation was suggested for this transformation. The CF3•, which was generated by reaction of tert-butyl hydroperoxide with

• -workers reported a metal-free protocol for the trifluoromethylation of styrenes with CF3SO2Na, tert-butyl hydroperoxide and benzoquinone (BQ) as oxidant. The reactions were run at 80 °C for 16 h to give mixtures of α-trifluoromethyl ketones 12 and the corresponding alcohols 13 (Scheme 6) [25]. The scope

Difunctionalization of alkenes with iodine and tert-butyl hydroperoxide (TBHP) at room temperature for the synthesis of 1-(tert-butylperoxy)-2-iodoethanes

• Hao Wang,
• Cui Chen,
• Weibing Liu and
• Zhibo Zhu

Beilstein J. Org. Chem. 2017, 13, 2023–2027, doi:10.3762/bjoc.13.200

• alkenes with iodine and tert-butyl hydroperoxide (TBHP) at room temperature to synthesize 1-(tert-butylperoxy)-2-iodoethanes that are inaccessible via conventional synthetic routes (Scheme 1). To the best of our knowledge, β-iodoalkyl tert-butyl peroxides are important organic compounds due to their

Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines

• Somaia Kamouka and
• Wesley J. Moran

Beilstein J. Org. Chem. 2017, 13, 1823–1827, doi:10.3762/bjoc.13.177

• [32][33][34][35][36]. Gao and co-workers described the I2-catalyzed cyclization of β-acylaminoketones using tert-butyl hydroperoxide as the oxidant; notably, adding DBU led to oxazole formation whereas adding K2CO3 generated oxazolines [37][38]. Our proposed new approaches to oxazoline formation

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• -transfer catalysis [110]. In this seminal investigation, they succeeded in carrying out the direct α-hydroxylation of simple ketones 15 by using O2 in combination with triethylphosphite, which leads to the in situ formation of a reactive hydroperoxide derivative. When using the easily accessible cinchona

• out the α-hydroxylation of substrates 1 by using cumyl hydroperoxide (22) as an easily available oxidizing agent, which worked well to access a series of differently substituted products 21 in high yields and with high enantioselectivities when using the carefully optimized sterically demanding PTC A2