[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

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• of diselenides as starting reagents, under an oxygen atmosphere and using PEG 200 as the solvent. This procedure involves the in situ generation of dialkyl diselenides through a K3PO4-assisted reaction of an alkyl selenocyanate obtained by a nucleophilic substitution reaction between KSeCN and alkyl

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• being excited with visible light, the PS – while reverting to the ground state – transfers the energy of its lowest excited triplet state to nearby molecular oxygen. This leads to an in situ generation of singlet oxygen (1O2), which is the main responsible species for cytotoxic reactions in cells [6

Contribution of microreactor technology and flow chemistry to the development of green and sustainable synthesis

• Flavio Fanelli,
• Giovanna Parisi,
• Leonardo Degennaro and
• Renzo Luisi

Beilstein J. Org. Chem. 2017, 13, 520–542, doi:10.3762/bjoc.13.51

• highly energetic reagents [79][80]. For this reason, the in situ generation of such reagents has been investigated under flow conditions. Moody and co-workers reported a new method for the in situ generation of diazo compounds as precursors of highly reactive metal carbenes (Scheme 16) [81]. As reported

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• diaryl thiocarbonyl S-methanides 1. The in situ generation of phenyl selenophen-2-yl S-methanide (8) and its competitive reactions: 1,3-ring closure, head-to-head dimerization, and macroheterocycle 9 formation via an intermediate diradical species 8B–D. Supporting Information Supporting Information File

Stabilization of nanosized titanium dioxide by cyclodextrin polymers and its photocatalytic effect on the degradation of wastewater pollutants

• Tamás Zoltán Agócs,
• István Puskás,
• Erzsébet Varga,
• Mónika Molnár and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2016, 12, 2873–2882, doi:10.3762/bjoc.12.286

• cyclodextrin polymer (CDP) using KMnO4 [19]. Advanced oxidation processes (AOPs) based on in situ generation of highly reactive species can mineralize organic contaminants into relatively harmless compounds. Research activities have been recently focused on photocatalysis belonging to these AOP techniques [20

Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

• Vladimir A. Stepchenko,
• Anatoly I. Miroshnikov,
• Frank Seela and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2016, 12, 2588–2601, doi:10.3762/bjoc.12.254

• , 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases

Sydnone C-4 heteroarylation with an indolizine ring via Chichibabin indolizine synthesis

• Florin Albota,
• Mino R. Caira,
• Constantin Draghici,
• Florea Dumitrascu and
• Denisa E. Dumitrescu

Beilstein J. Org. Chem. 2016, 12, 2503–2510, doi:10.3762/bjoc.12.245

• pyridinium salts used in the synthesis of sydnone-indolizine hybrids could be transformed into sydnone-indolizines connected via a keto group. The transformation was achieved by a one-pot procedure implying the in situ generation of sydnone-pyridinium N-ylides followed by 1,3-dipolar cycloaddition reaction

The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors

• Faith M. Akwi and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 1987–2004, doi:10.3762/bjoc.12.186

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• led to the development of a catalytic version of this cycloaddition. In principle, there are two conceptually different approaches for the catalytic hetero-Diels–Alder reaction reported in the literature [135], which will be exemplified below. a) The first approach is based on the in situ generation

• are able to complex a nitroso derivative with chiral ligands (Scheme 37). Approach based on the in situ generation and trapping of an intermediate acylnitroso dienophile: This approach is exemplified by the results of the Iwasa group from 2008. They performed asymmetric hetero-Diels–Alder reactions of

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• experiment for the in situ generation of [Rh(13CO)2Cl(dipyrido[1,2-c;2',1'-e]imidazolin-6-ylidene)] (13C2a). A medium wall NMR tube was charged with a yellow solution of 6.0 mg (15 μmol) [RhCl(COD)(dipiy)] (1a) in 0.4 mL CD2Cl2 and pressurized with 6 bar of 13CO upon which a yellow precipitate formed that

• -thaw cycles: δ 183.2 (dd, 1JRhC = 72.8 Hz, 2JCC = 6.1 Hz, cis-13CO), 186.3 (dd, 1JRhC = 54.5 Hz, 2JCC = 6.1 Hz, trans-13CO). NMR experiment for the in situ generation of [Rh(13CO)2Cl(2,10-di-tert-butyldipyrido[1,2-c;2',1'-e]imidazolin-6-ylidene)] (13C2b). A medium-wall NMR tube was charged with a

Synthesis of the C8’-epimeric thymine pyranosyl amino acid core of amipurimycin

• Pramod R. Markad,
• Navanath Kumbhar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2016, 12, 1765–1771, doi:10.3762/bjoc.12.165

• -dioxabicyclo[3.2.1]octane A could be glycosylated stereoselectively with the requisite nucleobase to give β-nucleoside pyranosyl skeleton 2. The bridged bicyclic system A was visualized from the azido diol B. Thus, hydrolysis of the 1,2-acetonide functionality in B will lead to in situ generation of

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

• Jakub Saadi,
• Christoph Bentz,
• Kai Redies,
• Dieter Lentz,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

• of organometallics such as lithium, magnesium or zinc organic compounds to carbonyl groups leading to alcohols is an important standard operation in organic synthesis providing high stereoselectivities in many cases. The in situ generation of the nucleophilic species from the corresponding organic

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• derivative 2-PyCOBt [25][26]. During an attempt to prepare β-ketoenamide 3a by in situ generation of picolinic acid chloride with thionyl chloride under heating and by amide formation of the resulting product with 2a we isolated not only the expected compound 3a but as major component the meta-chlorinated

• (see Supporting Information File 1). The in situ generation of the acid chloride with thionyl chloride was possible without the undesired chlorination with the more electron-deficient 6-methoxycarbonyl-substituted 2-pyridine carboxylic acid delivering with 2a the desired β-ketoenamide 3g with excellent

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• increase in the yield of 3a. In our opinion, this effect of the solvent or base on the yield of 2a may be explained by the formation of 2a through a heterocyclization of 2-azidobenzoate anions. Therefore, the role of the base in the reaction is the in situ generation of the 2-azidobenzoate anion and the

Iron complexes of tetramine ligands catalyse allylic hydroxyamination via a nitroso–ene mechanism

• David Porter,
• Belinda M.-L. Poon and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2015, 11, 2549–2556, doi:10.3762/bjoc.11.275

• ][24][25][26]. Several new developments in the related hetero-Diels–Alder reaction of acylnitroso species have also been reported recently [27][28][29][30]. These methodologies generally involve in situ generation of the acylnitroso species, achieved using a variety of oxidants including vanadium- [28