DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• as the requirement of high temperatures or use of strong oxidants (H2O2, oxone, K2S2O8, TBHP, PIDA, NHPI etc.) that are not much compatible with functionality, precluding late-stage functionalization. Moreover, the scope of substitution on the pyridine ring is limited which in turn hampers the

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

• transfer (HAT) to the alkene substrate, followed by interception of the resulting alkyl radical intermediate with a SOMOphile. In addition, we report the first reductive couplings of unactivated alkenes and aryldiazonium salts by an HAT pathway. The simplicity and generality of the Co(acac)2–TBHP–Et3SiH

• 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

• %) was obtained using PhI(OAc)2 (Table 1, entry 2). Other iodine-based oxidants, such as PhI(OCOCF3)2 (Table 1, entry 10, yield 31%), IBX (Table 1, entries 11 and 12, yield 32–54%), DMP (Table 1, entries 13–14, yield 52%), showed less efficacy in this process. Peroxide oxidants, such as TBHP, TBAI/TBHP

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• containing an alkyne moiety and sulfonylhydrazides 73 undergo intermolecular spirocyclization in presence of I2O5/TBHP oxidative system to give the sulfonated spirolactams 75 in high yields (Scheme 25). This oxidative system found to be more efficient and could sustain the presence of diverse functional

• diphenylacetylene (70) to spirolactam 71. Synthesis of spiroxyindole 75 using I2O5/TBHP oxidative system. Iodine(III)-catalyzed spirolactonization of functionalized amides 76 to spirolactones 77 using iodotoluene 33 as a precatalyst and mCPBA as an oxidant. Intramolecular cyclization of alkenes 78 to spirolactams

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

• 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

• mechanism adumbrated in Scheme 29 [66]. The thiyl radical resulting from the initial reaction of TBHP and thiophenol selectively adds to the terminal end of the C=C bond of 80 to form intermediate radical 82. Oxidation with O2 leads to the formation of peroxy radical 83, which abstracts a hydrogen radical

Functionalization of N-arylglycine esters: electrocatalytic access to C–C bonds mediated by n-Bu₄NI

• Mi-Hai Luo,
• Yang-Ye Jiang,
• Kun Xu,
• Yong-Guo Liu,
• Bao-Guo Sun and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2018, 14, 499–505, doi:10.3762/bjoc.14.35

• ]. Later on, arylation, vinylation and alkynylation of glycine derivatives were also accomplished by the same group (Scheme 1) [13]. Using the Cu(OAc)2/pyrrolidine dual catalysts system, Huang developed the oxidative cross coupling of glycine derivatives with acetone in the presence of TBHP or DDQ as

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

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

• ’ reagent, 1h, Scheme 22), which can generate trifluoromethyl radicals at room temperature in the presence of ambient air and moisture when combined with TBHP. Electron-neutral and -rich boronic acids proceeded smoothly to give the corresponding products in excellent yields. An addition of NaHCO3 was

• trifluoromethyl radical was generated from CF3SO2Na in the presence of TBHP at room temperature using a mixture of water and DCM as solvent. Arylboronic acids with electron-donating substituents proceeded smoothly to give the corresponding products in good yields. Common hydroxy protecting groups (Bn and TBS

• revealed that a radical mechanism was involved in this transformation. Recently, the group of Qing [48] accomplished a Sandmeyer trifluoromethylation of aryldiazonium derivatives with NaSO2CF3 in the presence of TBHP (Scheme 28). The yield was improved by adding the tridentate ligand 2,2′,6′,2″-terpyridine

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

• transfer on TBHP, which homolytically decomposes to generate a hydroxyl radical and a tert-butoxyl radical. Both species are able to abstract a hydrogen atom from the α-position of the ether. The obtained carbon-centred radical can further react with the nucleophilic disulfide to form the respective

• 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

• published the same reaction under slightly different conditions [46]. They used a combination CF3SO2Na/TBHP in the presence of catalytic amounts of copper chloride and triphenylphosphine. Trisubstituted alkenes (R3 and R4 ≠ H) were employed as substrates and diastereoisomers were obtained. The tert-butoxyl

• radical was generated from TBHP and Cu(n) via a SET process, which then, it reacted with CF3SO2Na to liberate CF3•. The subsequent addition of CF3• to the β-position of the C=C bond of the acrylamide gave the intermediate 48, which underwent an intramolecular radical annulation to produce the aryl radical

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

• , Maoming 525000, P. R. China. Fax: +86-668-2923575; Tel: +86-668-2923956 10.3762/bjoc.13.200 Abstract We developed a direct vicinal difunctionalization of alkenes with iodine and TBHP at room temperature. This iodination and peroxidation in a one-pot synthesis produces 1-(tert-butylperoxy)-2-iodoethanes

• applications and allow further chemical modifications, enabling the preparation of synthetically valuable molecules. Keywords: difunctionalization of alkenesiodine; iodination–peroxidation reaction; TBHP; Introduction Alkenes have attracted considerable interest in recent years as abundant, simple chemical

• 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

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• . Mal and co-workers reported a metal free, solvent-free and room temperature synthesis of amide bonds at 62–75% yield under ball-milling (21 Hz) from aromatic aldehydes and N-chloramine in presence of 20 mol % of tetrabutylammonium iodide (TBAI) and 2.0 equiv of TBHP (Scheme 16) [79]. Aromatic

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• catalytic amount of potassium iodide (0.2 mmol) and 0.25 mL of tert-butylhydroperoxide (TBHP, 70 wt %) in water (4 equiv) to afford the dihydroisoquinazoline 34a, which got oxidized to the quinazolium intermediate 34b. Hydroxylation of 34b afforded 34c, which was further reacted with nitroalkanes at 50 °C

• intermediate R´ which undergoes aromatization to provide the desired 86 (Scheme 31). Yamamoto et al. demonstrated a mild oxidative dehydrogenation of dihydropyrimidinones 88 and dihydropyrimidines 89 via catalytic copper salts and K2CO3 as base along with TBHP as the terminal oxidant (Scheme 32). The desired

• compounds 90 and 91 were obtained in excellent yields (Scheme 32) [92]. Two mechanisms were proposed for this conversion. In one the tert-butyl peroxy radicals were generated by the interaction of Cu salts with TBHP. This radical abstracts the C4 hydrogen of the dihydropyrimidine to generate P, which would

α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones

• Liquan Tan,
• Cui Chen and
• Weibing Liu

Beilstein J. Org. Chem. 2017, 13, 1079–1084, doi:10.3762/bjoc.13.107

• self-intermolecular oxidative coupling of aryl ketones using I2−tert-butyl hydroperoxide (TBHP). Under the optimum conditions, various aryl ketones gave the corresponding products in moderate to excellent yields. A series of control experiments were performed; the results suggest the involvement of

• radical pathways. Multiple radical intermediates were generated in situ and the overall process involved several different reactions, which proceeded self-sequentially in a single reactor. A labeling experiment using 18O-labeled H2O confirmed that the oxygen in the product was derived from TBHP, not from

• H2O in the TBHP solvent. Keywords: aryl ketones; iodine; self-intermolecular oxidative coupling; self-sequential assembly; TBHP; Introduction In recent years, α-acetoxyaryl ketones have attracted considerable interest because this structural motif is found in a variety of biologically active natural

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• at other positions. In 2015, Sun and co-workers developed a Pd(OAc)2 catalyzed ortho-hydroxylation of 2-arylpyridines using tert-butyl hydroperoxide (TBHP) as oxidant [62]. The reaction was carried out at 115 °C in 1,2-dichloroethane (DCE), affording the corresponding phenols in moderate to good

• yields (Scheme 33). The reaction yield were lowered by adding a radical-trapping reagent, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), indicating that radical HO·, which was generated from TBHP, may participate in the oxidation of the palladium complex from Pd(II) to Pd(IV). In 2016, Guin and co-workers

• directing groups: In 2016, the Zhang and Fan group described the first phenolic moiety directed hydroxylation. Pd(OAc)2 catalyzed hydroxylation of [1,1’-biphenyl]-2-ols using TBHP as oxidant in acetonitrile (Scheme 45) [74]. The reaction predominantly afforded biphenols as product, rather than dibenzofurans

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• developed the first direct sp3 C–H arylation of THIQ with arylboronic acids using a copper catalyst (Scheme 1) [30]. Oxygen gas and tert-butyl hydroperoxide (TBHP) were used as external oxidants, which gave moderate to good isolated yields (up to 75%). In addition, we demonstrated the first enantioselective

• temperature in the reaction with copper(I) bromide caused a significant drop in yield. During optimisation of the reaction system, TBHP was found to be the best external oxidant for this reaction over many others [31]. To accelerate the reaction at lower temperature, we reasoned that a light-mediated

• photoredox system might help, which indeed has improved the reaction yield and enantioselectivity. Different iridium and ruthenium photoredox catalysts were evaluated and [Ir(ppy)2(dtbbpy)]PF6 was found to be the most efficient [32]. With this iridium photoredox catalyst, TBHP, and copper(I) bromide co

Experimental and theoretical investigations into the stability of cyclic aminals

• Edgar Sawatzky,
• Antonios Drakopoulos,
• Martin Rölz,
• Christoph Sotriffer,
• Bernd Engels and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 2280–2292, doi:10.3762/bjoc.12.221

• with KMnO4 or a mixture of potassium iodide and tert-butyl hydroperoxide (TBHP) give access to quinazolinones and have been reported for the synthesis of the naturally occurring alkaloids deoxyvasicinone, mackinazolinone or rutaecarpine [22][28] (Scheme 2). Besides total oxidation of the aminal core

TBHP-mediated highly efficient dehydrogenative cross-oxidative coupling of methylarenes with acetanilides

• Cui Chen,
• Weibing Liu and
• Peng Zhou

Beilstein J. Org. Chem. 2016, 12, 2250–2255, doi:10.3762/bjoc.12.217

• Cui Chen Weibing Liu Peng Zhou College of Chemical Engineering, Guangdong University of Petrochemical Technology, 2 Guandu Road, Maoming 525000, P. R. China. Fax: +86-668-2923575; Tel: +86-668-2923444 10.3762/bjoc.12.217 Abstract A TBHP-mediated dehydrogenative cross-oxidative-coupling approach

• C–N bonds. Besides, this conversion is an important complement to the conventional C–N forming strategies. Keywords: dehydrogenative cross oxidative coupling; methyl arenes; N-arylbenzamides; TBHP; Introduction Recently, amides have attracted more and more attention due to their extensive

• are rather limited, and which would be an important complement to the conventional C–N forming strategies. Herein, we disclose a dehydrogenative C–N cross-oxidative-coupling reaction of methylarenes with acetanilides, using TBHP as an oxidant to afford N-arylamides in moderate to good yields (Scheme 1

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• -methylallyl)benzamide (4a) and cyclohexane (2a) as model compounds (Table 1). As shown in Table 1, we found that the reactions did not happen or gave only a trace amount of the desired product with K2S2O8, AIBN, BPO and TBHP as oxidants (Table 1, entries 1, 3–5). PhI(OAc)2 and DCP could be used as oxidants

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• ] reported the copper-catalyzed, tert-butyl hydroperoxide (TBHP)-assisted C–H amidation of tertiary amines 1. By heating at 80 °C, the C–H bond in dimethylaniline underwent direct amidation to provide products 3 in the presence of amides 2. On the other hand, the dephenylation transformation via C–C bond

• ) via the intramolecular amidation of N-methyl-o-formylbenzamide (59) (Scheme 16). More recently, Lan et al. [66] realized the C–H amidation of N,N-dialkylformamides 61 using pyridine-2-yl-functionalized amides 62 or 63. Under catalytic conditions consist of CuBr and TBHP, imides 64 and 65 were afforded

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• epoxidation of 5 with tert-butylhydroperoxide (TBHP) in toluene gave 6 ([α]D +34.2° (c 1.3, CHCl3)) in 95% yield [9][22]. Then, the diol 7 was obtained in 85% yield from the reduction of epoxide 6 with LiAlH4 in THF at 0 °C. The diol 7 was easily purified by crystallization (85% yield, n-hexane at −50 °C up

• conditions: (a) (i) t-BuOK, BuLi, hexane, −10 °C/rt; 2 h; (ii) BrCH2CH=C(CH3)2; −10°C/rt, 1 h; (b) TBHP, cat. VO(acac)2, toluene, rt, 13 h; (c) LiAlH4, THF, 0 °C, 5 h; (d) DMP, CH2Cl2, 0 °C/rt, 14 h; (e) TMSCl, CH2Cl2/pyridine (2:1), rt, 13 h; (f) LDA, TMSCl or TESCl, −78 °C/rt, THF; (g) see Table 2; (h

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

P(O)R₂-directed Pd-catalyzed C–H functionalization of biaryl derivatives to synthesize chiral phosphorous ligands

• Rong-Bin Hu,
• Hong-Li Wang,
• Hong-Yu Zhang,
• Heng Zhang,
• Yan-Na Ma and
• Shang-dong Yang

Beilstein J. Org. Chem. 2014, 10, 2071–2076, doi:10.3762/bjoc.10.215

• (20 mol %), AgOAc (1.5 mmol), TFE (3.0 mL), 100 °C, 24 h, air atmosphere; bSubstrate (0.3 mmol), PhI(OAc)2 (0.9 mmol), Pd(OAc)2 (10 mol %), TFE (3.0 mL), 100 °C, 24 h, air atmosphere; cSubstrate (0.3 mmol), TBHP (1.2 mmol), benzyl alcohol (0.75 mmol), Pd(TFA)2 (10 mol %), DCE (3.0 mL), 60 °C, air