One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• an alkyl halide. Earlier, we used butyl bromide for anion 3 trapping and obtained 4-butyl-4'-cyanobiphenyl (5aa) in 56% yield (Table 1, entry 1) [23]. In order to expand the scope of the synthetic utilization of the cross-coupling reaction under investigation, as well as to work out a short and

• , stirring the reaction mixture for ca. 1.5 h, which is necessary for cross-coupling, and final quenching by the addition of an excess of alkyl halide 6. The reaction proceeds under evaporating ammonia at −33 °C, and it does not need an additional source of inert atmosphere for the overall reaction time

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• derivative with 1,2-dibromoethane. In order to avoid the presence of halide ions as inhibitory ligands for copper(I) [2][41], bisthiazolium hexafluorophosphate 1b was obtained by a salt metathesis from bromide salt 1a with aqueous hexafluorophosphoric acid (Figure 1). The final step is the reaction with

• ). Disfavored mononuclear pathway and favored dinuclear pathway in the CuAAC click reaction, according to the mechanistic proposal of reference [37]. R, R’ = alkyl, aryl, silyl, carbonyl groups; L = NHC; L’ = NHC or solvent; L’’ = solvent, acetylide, carboxylate, halide. Synthesis of dinuclear copper complex 2

Flow carbonylation of sterically hindered ortho-substituted iodoarenes

• Carl J. Mallia,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147

• aryl halide, an associative mechanism for the complexation of carbon monoxide on the d8 square planar intermediate would occur prior to the key migratory insertion step. In the complex, the aryl group would be oriented perpendicularly to the plane to minimise steric interactions thus placing the ortho

NeoPHOX – a structurally tunable ligand system for asymmetric catalysis

• Jaroslav Padevět,
• Marcus G. Schrems,
• Robin Scheil and
• Andreas Pfaltz

Beilstein J. Org. Chem. 2016, 12, 1185–1195, doi:10.3762/bjoc.12.114

• difficult, literature precedence indicated that the introduction of the phosphine group might be possible by the reaction of a diarylphosphide anion with chloroalkyloxazoline 2. Ashby et al. [20] investigated the reactivity of neopentyl halide systems with various metal diphenylphosphides and found that the

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

• bond [27][28][29][30], single electron transfer (SET) to a α-halo anilides followed by halide elimination [31][32], and the formation of an aryl radical followed by a 1,5-hydrogen atom translocation [33][34]. Out of these strategies, the initial two require specifically functionalized precursors such

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• 7TJ, UK 10.3762/bjoc.12.103 Abstract Here we report the chemoselective synthesis of several important, climate relevant isoprene nitrates using silver nitrate to mediate a ’halide for nitrate’ substitution. Employing readily available starting materials, reagents and Horner–Wadsworth–Emmons chemistry

• studied their ability to undergo an ‘allylic halide for allylic nitrate’ substitution reaction which we demonstrate generates (E)- and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate, and (E)- and (Z)-2-methyl-4-hydroxybut-2-enyl nitrates (‘isoprene nitrates’) in 66–80% overall yields. Using NOESY experiments

• the elucidation of the carbon–carbon double bond configuration within the purified isoprene nitrates has been established. Further exemplifying our ‘halide for nitrate’ substitution chemistry we outline the straightforward transformation of (1R,2S)-(−)-myrtenol bromide into the previously unknown

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• complexes are commercially available, they may also be generated in situ via a variety of routes (Scheme 2), including: (a) reaction of a palladium complex with a non-coordinating anion source, usually an acid or metal salt; (b) reaction of Pd(II) halide complexes and silver salts [143][144][145]; (c

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• corresponding halide in the presence of sodium hydride, giving thus access to thioether derivatives of type 68, which can also be converted into γ-lactams such as 69. On the other hand, experiments carried out with pyridyl and quinoylthiazolone substrates reveal that in these cases selectivity is higher than

A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

• Vladislav Vasilenko,
• Torsten Roth,
• Clemens K. Blasius,
• Sebastian N. Intorp,
• Hubert Wadepohl and
• Lutz H. Gade

Beilstein J. Org. Chem. 2016, 12, 846–853, doi:10.3762/bjoc.12.83

• similarities. Bond lengths and bond angles of the chelate ring agree well, underlining that halide abstraction is effectively compensated by the bridging chlorides (Table 3). Significant structural deviations are only observed for the Pd–Cl bonds, where significantly longer bonds were found for the cationic

Creating molecular macrocycles for anion recognition

• Amar H. Flood

Beilstein J. Org. Chem. 2016, 12, 611–627, doi:10.3762/bjoc.12.60

• , the question of how all these donors perform so well inside the triazolophane defined a research agenda that continues to this day. Ideas such as the macrocycle’s rigid shape-persistence must also play a role. Testing structure–property relationships for triazolophanes: electronics, halide selectivity

Studies on the synthesis of peptides containing dehydrovaline and dehydroisoleucine based on copper-mediated enamide formation

• Franziska Gille and
• Andreas Kirschning

Beilstein J. Org. Chem. 2016, 12, 564–570, doi:10.3762/bjoc.12.55

• conjugated alkene. Principally, enamides can also be prepared by the copper-mediated C–N coupling between a vinyl halide 6 and an amide 5 as reported by Ogawa and co-workers in 1991 [6]. Later, the group of Porco showed that copper(I) thiophencarboxylate is a suitable catalyst to promote this reaction in the

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• considered satisfactory because of the ready availability of starting materials and the modest reaction time of 4 hours. Since the starting materials in the Suzuki–Miyaura cross-coupling tolerate a wide variety of functional groups, facile and versatile combination of different dihydroxybenzyl halide

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• proved to be viable substrates, smoothly providing 1,2-oxyamino products 4a–g. Carboxylic acids containing a nitro group (4b), a halide group (4d), or an allyl group (4f) were tolerated, demonstrating the broad functional group compatibility of the reaction conditions. It is notable that higher

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• chelating ligands and thus compete with the chiral ligand for binding with the copper salts. Therefore the authors used a mono-aryl halide-substituted malonamide in the presence of a chiral CuI/1,2-diamine catalyst system and obtained the desired products in good yields and moderate enantioselectivities [48

Comparison of the catalytic activity for the Suzuki–Miyaura reaction of (η⁵-Cp)Pd(IPr)Cl with (η³-cinnamyl)Pd(IPr)(Cl) and (η³-1-t-Bu-indenyl)Pd(IPr)(Cl)

• Patrick R. Melvin,
• Nilay Hazari,
• Hannah M. C. Lant,
• Ian L. Peczak and
• Hemali P. Shah

Beilstein J. Org. Chem. 2015, 11, 2476–2486, doi:10.3762/bjoc.11.269

• the olefin ligand from C generates the active monoligated Pd(0) species, which in catalysis undergoes oxidative addition with the aryl halide, but in the case of our activation experiments is trapped by dvds. The considerably faster rate of activation for Cp compared to Cin, suggests that Cp should be

Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

• Bijay Shrestha and
• Ramesh Giri

Beilstein J. Org. Chem. 2015, 11, 2400–2407, doi:10.3762/bjoc.11.261

• ). Alkyl halide (1.0 mmol), CuI (1.9 mg, 0.010 mmol, for alkyl iodides; 19.0 mg, 0.10 mmol, for alkyl bromides) and NN-1 (1.6 mg, 0.010 mmol, for alkyl iodides; 16.4 mg, 0.10 mmol, for alkyl bromides) were then added to the solution of the triarylaluminum reagent. The reaction mixture was then tightly

Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines with aryl iodides

• Svetlana P. Panchenko,
• Alexei D. Averin,
• Maksim V. Anokhin,
• Olga A. Maloshitskaya and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2015, 11, 2297–2305, doi:10.3762/bjoc.11.250

• , it has been found that to obtain a good result, the reaction conditions (ligand, solvent, temperature) should be adjusted for a certain aryl halide/polyamine pair. In the present study we decided to undertake a thorough investigation of the Cu(I)-catalyzed N,N’-diarylation of natural diamines and

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• recent examples from this emergent area, including copper-catalyzed alkylation reactions of nitroalkanes, alkenes and alkynes. Results and Discussion Additions to nitronate anions The selective C-alkylation of nitroalkanes with alkyl halide electrophiles is a long-standing challenge in organic synthesis

• such as TEMPO. Radical clock experiments provided ring-opened products, suggesting the presence of intermediate radicals. We propose that this reaction proceeds via a thermal redox process. We hypothesize that the alkyl radical is formed by transfer of a bromine atom from the alkyl halide to the copper

• catalyst. The resultant stabilized alkyl radical then undergoes coupling with a nitronate anion, forging the C–C bond. Single electron transfer from the resultant radical anion to the Cu(II) halide results in the observed product while simultaneously reducing the metal center to regenerate the catalyst. In

Evidencing an inner-sphere mechanism for NHC-Au(I)-catalyzed carbene-transfer reactions from ethyl diazoacetate

• Manuel R. Fructos,
• Juan Urbano,
• M. Mar Díaz-Requejo and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2015, 11, 2254–2260, doi:10.3762/bjoc.11.245

• )phenyl)borate) as a halide scavenger, induced the incorporation of the :CHCO2Et group from N2CHCO2Et to styrene (Scheme 2a) or methanol (Scheme 2b), among others. With the former, in addition to the formation of the expected cyclopropanes, a second type of product was observed, derived from the

• precursors were dissolved in the neat substrate (5 mL) and stirred for 30 min to ensure halide abstraction prior to EDA addition. The experiments have been carried out using a flask connected to a pressure gauge that provides the variation in the increase of the internal pressure (see Experimental). Figure 1

• that the addition of 5 equiv of NaBArF4 did not induce any change in the reaction rate compared with that of one equiv, assessing that the halide-free catalytically-active gold species is available in the latter case. Also, the fact that the same behavior regarding the “dilution effect” shown in Figure

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• since low selectivity between monochlorinated products 2 and dichlorinated products 7 was suffered (Scheme 3). Two years later, the same group developed a modified approach for this kind of C–H chlorination by employing lithium halide (LiCl or LiBr) as the source of halogen to react with 2-arylpyridine

• ] devised a practical copper-catalyzed halogenation of anilines 8 containing an easily removable N-(2-pyridyl)sulfonyl auxiliary. In the presence of copper(II) halide catalyst and NXS (X = Cl or Br), a class of o-chloro/bromoanilines 9 were efficiently provided under aerobic atmosphere (Scheme 6). The N-(2

• biological functions of halogenated heteroarenes [57], the synthesis of haloheteroarenes via the corresponding arene C–H halogenations also gained extensive attention. In 2009, Pike and co-workers [58] reported the synthesis of halogenated 1,3-thiazoles using copper(II) halide as a catalyst. As shown in

Nitro-Grela-type complexes containing iodides – robust and selective catalysts for olefin metathesis under challenging conditions

• Andrzej Tracz,
• Mateusz Matczak,
• Katarzyna Urbaniak and
• Krzysztof Skowerski

Beilstein J. Org. Chem. 2015, 11, 1823–1832, doi:10.3762/bjoc.11.198

• - analogues of HII, but no improvement was noted [13][14][15]. Moreover, the presence of iodide ligands reduced initiation rates for Hoveyda second generation complex bearing iodides (HII-I2) in ring-closing metathesis (RCM). Similarly, Schrodi and colleagues did not find any advantages for halide exchanged

A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

• Albert Poater and
• Luigi Cavallo

Beilstein J. Org. Chem. 2015, 11, 1767–1780, doi:10.3762/bjoc.11.192

• pyridine is roughly 20 kcal/mol, with a small effect of the ligand bulkiness, which only changes for system 8 bearing more sterically demanding isopropyl groups, displaying a value of 15.0 kcal/mol. The pseudo-halide systems, instead, show a remarkably different behavior. The pyridine is quite weakly bound

• coordinated in 11 and 12. Considering the pseudo-halide family, our results are in qualitative agreement with the experimental finding of Fogg and co-workers that systems 11 and 12 have to be thermally activated [19], while system 10 is even more active than the prototype 2nd generation system 7. Finally, the

• the Cl atom cis to the SIMes ligand. Moving to the pseudo-halide systems with a chelating ligand, the most striking difference is in the absolute C2H4 coordination energy, roughly 30 kcal/mol, which is about 15 kcal/mol better than in the non-chelating ligands. The chelating ligand has a minor effect

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• the original substrates 1 by swapping the locations of the radical precursor (halide) and the radical acceptor (ene-sulfonamide). The expected products of these reactions, imines like 19, could possibly be used to make spirocyclic oxindole natural products like coerulescine [18], horsfiline [19][20

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• , entry 12). This supports the hypothesis that complexes 1 and 2 are bifunctional catalysts in which both the aluminium centre and the ammonium halide play important catalytic roles. After finding the optimal reaction conditions for each catalyst, both complexes 1 and 2 were tested with a range of

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• halide ions, 3 formed the C60 complex 5, in which C60 was bound within the bowl-like cup of the TTF-calix[4]pyrrole core in a ball-and-socket binding mode [43]. Recently, the C3-symmetric compounds 6a,b incorporating three TTF residues were reported by Amabilino, Avarvari, and co-workers (Figure 3) [21