Metal-free mechanochemical oxidations in Ertalyte^® jars

• Andrea Porcheddu,
• Francesco Delogu,
• Lidia De Luca,
• Claudia Fattuoni and
• Evelina Colacino

Beilstein J. Org. Chem. 2019, 15, 1786–1794, doi:10.3762/bjoc.15.172

• a catalytic amount of KBr promotes the in situ generation of HOBr, which is a stronger oxidant than HOCl [57]. The results improved remarkably by using as oxidant a 6% aqueous solution of NaOCl (1.14 mL, 1.1 mmol) adsorbed on NaHCO3 (6.5 g) in the presence of a catalytic amount of TEMPO (5.0 mol

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• reaction mechanism comprises of an in situ generation of the imine from the aldehyde and 2-AP. Further, the addition of alkyne and activation by CuO(II)/Cu2O(I) yielded the A3-coupled propargyl amine [40]. Tautomerization/5-exo-dig cyclization led to the formation of the final product. The reaction enjoyed

A three-component, Zn(OTf)₂-mediated entry into trisubstituted 2-aminoimidazoles

• Alexei Lukin,
• Anna Bakholdina,
• Anna Kryukova,
• Alexander Sapegin and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2019, 15, 1061–1064, doi:10.3762/bjoc.15.103

• .15.103 Abstract A three-component reaction involving in situ generation of propargylureas and subsequent Zn(OTf)2-mediated cyclocondensation with a primary amine yielded trisubstituted 2-aminoimidazoles. These findings are in contrast to the previously reported base-promoted unimolecular cyclization of

Synthesis of the aglycon of scorzodihydrostilbenes B and D

• Katja Weimann and
• Manfred Braun

Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56

• . Here, a modified version based upon an in situ generation of the ruthenium complex described by Genet and Darses [16] was applied. Thus, O-protected 2,5-dihydroxyacetophenones 6 were submitted to a hydroarylation reaction with two equivalents of styrenes 7 in the presence of [Ru(p-cymene)Cl2]2 and P(4

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• . Deprotonation of the latter with triethylamine in the presence of elemental sulfur allows the in situ generation of the corresponding imidazol-2-ylidene, which traps elemental sulfur yielding a 1,3-dihydro-2H-imidazole-2-thione as the final product. Keywords: alkoxyamines; imidazole N-oxides; imidazolium salts

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• results in the in situ generation of pyridinium hydroxide, resulting in further NR+ hydrolysis. This unfavorable reactivity of the C-1′ position was briefly addressed in the earlier sections of this review, as evidenced by the needs of anhydrous conditions and low temperatures in the deprotection steps to

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• regioselective hydroformylation of aromatic olefins [84]. Interestingly, if transition metals can initiate an ionic hydroformylation reaction of aryl olefins, a free radical pathway could be promoted by use of diethoxyacetic acid and 4CzIPN, inducing the in situ generation of an equivalent of a formyl radical

A tutorial review of stereoretentive olefin metathesis based on ruthenium dithiolate catalysts

• Daniel S. Müller,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2018, 14, 2999–3010, doi:10.3762/bjoc.14.279

• render this class of catalyst available to every practicing chemist [25]. A very practical and operationally simple protocol for the in situ generation of Ru-dithiolate catalysts was reported. First, the commercially available dithiol 48 is deprotonated with Et2Zn to provide Zn-dithiolate 49 (Scheme 8

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes

• Muhammad Israr,
• Changqing Ye,
• Munira Taj Muhammad,
• Yajun Li and
• Hongli Bao

Beilstein J. Org. Chem. 2018, 14, 2916–2922, doi:10.3762/bjoc.14.270

• are considered to be unstable moieties that can decompose spontaneously, with which the reactions are difficult or dangerous to handle [16]. Thus, a one-pot two-step process for the in situ generation of organic azides is highly required. A frequently used method to in situ generate organic azides is

Unprecedented nucleophile-promoted 1,7-S or Se shift reactions under Pummerer reaction conditions of 4-alkenyl-3-sulfinylmethylpyrroles

• Takashi Go,
• Akane Morimatsu,
• Hiroaki Wasada,
• Genzoh Tanabe,
• Osamu Muraoka,
• Yoshiharu Sawada and
• Mitsuhiro Yoshimatsu

Beilstein J. Org. Chem. 2018, 14, 2722–2729, doi:10.3762/bjoc.14.250

• (diols). Seleno-Pummerer reactions of 3-selanylmethylpyrroles also proceeded via in situ generation of selenoxides, followed by a treatment with TBAH. Keywords: hydroamination; Pummerer reaction; pyrrole; pyrroloazepine; 1,7-sulfur shift; Introduction Pyrrolo- and indoloazepine skeletons are chemical

One-pot synthesis of epoxides from benzyl alcohols and aldehydes

• Edwin Alfonzo,
• Jesse W. L. Mendoza and
• Aaron B. Beeler

Beilstein J. Org. Chem. 2018, 14, 2308–2312, doi:10.3762/bjoc.14.205

• through in situ generation of sulfonium salts from benzyl alcohols and their subsequent deprotonation for use in Corey–Chaykovsky epoxidation of aldehydes. The generality of the method is exemplified by the synthesis of 34 epoxides that were made from an array of electronically and sterically varied

A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines

• Katherine E. Jolley,
• Michael R. Chapman and
• A. John Blacker

Beilstein J. Org. Chem. 2018, 14, 2220–2228, doi:10.3762/bjoc.14.196

• (Figure 2). Using a 5-stage variant, various unsymmetrical N-chloramines were produced with unprecedented productivities (Table 1). The rapid nature of this chlorination step makes in situ generation and consumption feasible in flow mode. Comparing Table 1, entries 1 and 3, the 5-stage CSTR, with one

Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant

• Irina A. Mironova,
• Pavel S. Postnikov,
• Rosa Y. Yusubova,
• Akira Yoshimura,
• Thomas Wirth,
• Viktor V. Zhdankin,
• Victor N. Nemykin and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159

• towards some substrates. Moreover, these reagents are generally not suitable as active species in catalytic reactions due to the low reactivity and harsh conditions required for their in situ generation. In 2009, Ishihara and co-workers have reported an extremely active catalytic system for oxidation of

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• products. In addition, inorganic oxidants and peracetic acids can be used as oxidants as well. In 2005, the Ochiai and Kita groups demonstrated that m-chloroperbenzoic acid (mCPBA) was a better choice for the in situ generation of hypervalent iodine reagents through oxidation of iodoarenes [37][38]. Based

• under mild conditions [78]. The authors proposed a radical pathway involving the in situ generation of Br2, which opens the avenue for a reliable, ecologically benign, and safe dibromination method. Conclusion In the last two decades, great progress was made in hypervalent iodine(III) catalytic systems

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• following the discovery of practical procedures for the in situ generation of iminoiodinanes, a synthesis which is known to be troublesome [91][92][93]. According to these protocols and following the design of dirhodium(II) complexes, highly efficient catalytic nitrene transfers have been reported from

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• -bistriflates) with two different dipoles from which one was 3-phenyl-4-(4-methoxyphenyl)sydnone (Scheme 14). The reason for the much better regioselectivity probably lies in the steric hindrance between the bulky t-BuMe2Si and 4-MeO-Ph groups. The in situ generation of arynes or six-membered cycloalkynes from

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• , the intact 2-iodoaryl group is transferred via presumed transition state TS1, which leads to a good AE (50% for 22a) and allows the further transformation of the α-arylation product 22 via cross coupling reactions. In addition, the in situ generation of the PIFA reagent proved viable, in order to

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• a high level of enantioselectivity. Naphthol derivatives 31 were converted to spirocyclic lactones 32 in the presence of m-CPBA as co-oxidant for the in situ generation of the I(III) catalyst. Secondary n–π* and/or hydrogen-bonding interactions of the catalyst ensured remarkable enantioselectivities

Fluorocyclisation via I(I)/I(III) catalysis: a concise route to fluorinated oxazolines

• Felix Scheidt,
• Christian Thiehoff,
• Gülay Yilmaz,
• Stephanie Meyer,
• Constantin G. Daniliuc,
• Gerald Kehr and
• Ryan Gilmour

Beilstein J. Org. Chem. 2018, 14, 1021–1027, doi:10.3762/bjoc.14.88

• methods. To contribute to the current catalysis ordnance for the preparation of 2-oxazolines, and provide a direct route to 5-fluoromethyl derivatives from simple unactivated alkenes, the fluorocyclisation of N-allylcarboxamides facilitated by the in situ generation of p-TolIF2 was envisaged [8][9][10][11

A stereoselective and flexible synthesis to access both enantiomers of N-acetylgalactosamine and peracetylated N-acetylidosamine

• Bettina Riedl and
• Walther Schmid

Beilstein J. Org. Chem. 2018, 14, 856–860, doi:10.3762/bjoc.14.71

• improvement can be explained by a protonation of TMSN3 causing the in situ generation of highly reactive HN3 (Scheme 3). Additionally, no acidic work-up, as described by Miyashita et al., was necessary to gain the free alcohol on C5, which corroborates the proposed mechanism. The protecting groups were

One-pot synthesis of diaryliodonium salts from arenes and aryl iodides with Oxone–sulfuric acid

• Natalia Soldatova,
• Pavel Postnikov,
• Olga Kukurina,
• Viktor V. Zhdankin,
• Akira Yoshimura,
• Thomas Wirth and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 849–855, doi:10.3762/bjoc.14.70

• hypervalent iodine(III) species can be used as stable reagents or can be generated in situ [21][22][23][24][25]. In particular, Olofsson and co-workers reported procedures based on the in situ generation of reactive λ3-iodane species directly from arenes, which was a significant achievement in this field [26

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

• photoredox catalysis. Photoredox-catalysed trifluoromethylation/cyclisation of an o-azidoarylalkynes. Regio- and stereoselective chlorotrifluoromethylation of alkynes. PMe3-mediated trifluoromethylsulfenylation by in situ generation of CF3SCl. (EtO)2P(O)H-mediated trifluoromethylsulfenylation of (hetero

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

• ) addition of TEMPO suppressed the reaction; (ii) an induction period was observed followed by acceleration with consumption of styrene; (iii) vinyl triflone was detected indicating the formation of CF3SO2•; (iv) formation of CF3SO3– via oxidation of CF3SO2• (Scheme 16). A metal-free approach with in situ

• generation of the peroxide from the combination of NMP and O2 as the radical initiator was proposed by Lei and co-workers [36]. This method was based on a previous work by Maiti (see Scheme 5) [24] but did not require a metal to generate the CF3 radical. Tertiary β-trifluoromethyl alcohols 36 were obtained

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

• allylamine structure exists in numerous natural products [60]. Moreover, allylamines are widely used in the synthesis of compounds such as β-aminohydroxylamines, β- and γ-amino acids, pseudopeptides, spermidine derivatives or five- and six-membered heterocyclic systems [56]. 2.3.2. In situ generation of α,β

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• in situ generation of iodotrimethylsilane that result from a halogen exchange reaction [169]. This method (ClSiMe3 + NaI in acetonitrile) is currently less employed likely due to the need to remove NaI from the final phosphonic acid after the step of hydrolysis or methanolysis. It is worth noticing