Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• ]. One of the most prominent examples are the palladium catalyzed cross-coupling reactions [2], but in addition palladium complexes recently received much attention also in the field of selective CH oxidations [3][4][5][6]. The catalytic conversion of alkanes and especially of methane into a value-added

From N-vinylpyrrolidone anions to modified paraffin-like oligomers via double alkylation with 1,8-dibromooctane: access to covalent networks and oligomeric amines for dye attachment

• Daniela Obels,
• Melanie Lievenbrück and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 1395–1400, doi:10.3762/bjoc.12.133

• term paraffin means parum affinis or poor reactivity and comprises acyclic alkanes. They are obtained as byproducts in petroleum industry [28][29]. Technical derivatives are chloro- and chlorosulfonated paraffins which are used, e.g., as surfactants [30][31][32][33]. In the current paper we wish to

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

• , α-farnesene, β-gurjunene, β-muurolene and allo-aromadendrene, as well as simple alkanes, alkenes, alcohols, esters, aldehydes, ketones and carboxylic acids [3]. The quantities of BVOCs released far exceed non-methane hydrocarbon emissions derived from anthropogenic activity (~90 Tg C yr−1 where 1 Tg

Enantioselective carbenoid insertion into C(sp³)–H bonds

• J. V. Santiago and
• A. H. L. Machado

Beilstein J. Org. Chem. 2016, 12, 882–902, doi:10.3762/bjoc.12.87

• for enantioselective carbenoid insertion into C(sp3)–H bonds [70]. The reaction with acyclic alkanes showed regioselectivity in favor of the formation of the insertion product into primary carbons in modest stereoselectivity (Scheme 23). The preference for the reaction in less hindered carbon was

• attributed to high steric demand required by the chiral ligand in the transition state of the carbenoid insertion step in the C(sp3)–H bond. Cyclic alkanes were also tested with yields ranging from 64–80% and enantioselectivities between 88 and 92% ee. The reaction with cyclohexane was conducted on a gram

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• development of intermolecular C–H insertion in the application of C(sp3)–H bond functionalizations, especially for light alkanes, is reviewed. The challenging problem of regioselectivity in C–H bond insertions has been tackled by the use of sterically bulky metal catalysts, such as metal porphyrins and silver

• (I) complexes. In some cases, high regioselectivity and enantioselectivity have been achieved in the C–H bond insertion of small alkanes. This review highlights the most recent accomplishments in this field. Keywords: alkane; diazo compounds; C–H bond functionalization; C–H bond insertion; metal

• development of various directing groups for controlling the site-selectivity of the reaction. Regardless of the great efforts devoted to the field, the intermolecular C(sp3)–H bond activation of simple alkanes still remains a formidable challenge, obviously attributed to the inertness and ubiquitous nature of

From steroids to aqueous supramolecular chemistry: an autobiographical career review

• Bruce C. Gibb

Beilstein J. Org. Chem. 2016, 12, 684–701, doi:10.3762/bjoc.12.69

• two caveats to this statement. First, very small guests such as methane form 1:1 complexes; the cut-off for simple alkanes is between ethane and propane; the former forms a 1:1 complex whilst the latter forms a kinetically stable 2:2 capsular complex. Second, if guest binding generates a rather

• its overall affinity for the capsule and hence will affect any application that these types of complex are applied to. One straightforward approach to examining how flexible guests pack within these capsules is to consider the n-alkanes, the homologous series of which is available in pure form all the

• undergo compression [48]. For alkanes such as C14H30 the guest adopts a helical form; one that is of high energy in solution because of the gauche interactions down the length of the chain, but within the capsule maximizes non-covalent contacts between host and guest. With larger species such as C18H38

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

• cross-dehydrogenative coupling (CDC) reactions of alkanes, which were reported by Li and other groups [11][12][13][14][15]. Recently, several types of reactions with alkanes as substrates have been developed, such as the Minisci reaction with heteroarenes [16][17], radical addition to unsaturated bonds

• -initiated cyclization [30][31] and other radical reactions [32][33][34]. Due to their low polarity and high bond-dissociation energy, the functionalization of unactivated sp3 C–H bonds in simple alkanes remains as a challenging task. The direct cascade, 1,2-alkyarylation of alkenes to construct multi

• alkanes resulting in alkyl-substituted oxindoles (Scheme 1a) [43]. However, cyclization of N-allylbenzamides initiated by the functionalization of sp3 C–H bonds of simple alkanes remains unexplored. Very recently, our group developed a metal-free hydroxyalkylation-initiated radical six-membered

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• , aldehydic acids, alkanes and alkenes [17]. In the case of fish oil, the main odoriferous compounds resulting from oxidation are propanal, pent-1-en-3-one, hex-3-enal, and pent-1-en-3-ol [18][19][20]. The stabilization of fish oils can be simply performed by using antioxidants. Natural or synthetic

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• homologous series of alkanes, not an analysis of a host–guest system. All these values suggest that freezing out a single bond rotation is not terribly costly but association constants can drop significantly if too much flexibility exists; freezing five single bonds within a complex would lower its stability

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

• ). While most known literature methods in the copper-catalyzed alkane amidation focused on the transformation of either benzylic, allylic C–H bonds or C–H bonds adjacent to nitrogen or oxygen atoms, the amidation of unactivated C–H bonds in simple linear or cyclic alkanes remained as a challenge. Recently

• , Hartwig and co-workers [50] successfully realized the amidation, sulfonamidation and imidation reactions of purely non-activated cyclic and linear alkanes via the catalysis of copper(I) iodide by employing 4,7-dimethoxyphenanthroline ((OMe)2Phen) as the ligand and t-BuOOt-Bu as an oxidant. Heating the

• sulfonamidation of C–H bonds adjacent to oxygen. Copper-catalyzed amidation and sulfonamidation of inactivated alkyl C–H bonds. Copper-catalyzed amidation and sulfonamidation of inactivated alkanes. Copper-catalyzed intramolecular C–H amidation for lactam synthesis. Copper-catalyzed intramolecular C–H amidation

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

• fluorination of alkanes. Copper-catalyzed or mediated C–H halogenations of active C(sp3)-bonds. Acknowledgements The authors thank the financial support from Natural Science Foundation of China (21562024, 21202064) and Natural Science Foundation of Jiangxi Province (20142BAB213007).

Stereochemistry of ring-opening/cross metathesis reactions of exo- and endo-7-oxabicyclo[2.2.1]hept-5-ene-2-carbonitriles with allyl alcohol and allyl acetate

• Piotr Wałejko,
• Michał Dąbrowski,
• Lech Szczepaniak,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 1893–1901, doi:10.3762/bjoc.11.204

• obtained at 70 eV of ionization energy. The MS detector was set to scan 40–600 a.m.u. After integration, the fraction of each component in the total ion current was calculated. Retention indices (RI) were calculated according to the formula proposed by van Den Dool and Kratz [25] with n-alkanes as

Active site diversification of P450cam with indole generates catalysts for benzylic oxidation reactions

• Paul P. Kelly,
• Anja Eichler,
• Susanne Herter,
• David C. Kranz,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2015, 11, 1713–1720, doi:10.3762/bjoc.11.186

• –alkyl compounds [3], olefins [4], polycyclic aromatic hydrocarbons [5], terpenes [6][7][8] and alkanes as small as ethane [9]. Over the years a number of active site mutants of P450cam have been generated by rational re-design, but the active site has not been explored in a comprehensive and systematic

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• compounds. Notably, Bard and co-workers investigated the photo-Kolbé reaction, in which simple carboxylic acids RCO2H were decarboxylatively reduced to the corresponding alkanes RH on irradiation with platinized TiO2 in CH3CN under anaerobic conditions [35][36][37]. Only adamantane, from adamantane-1

• -bis(arylethylthio)alkanes 48 in good yields (Scheme 10). Initial reductive processes with acceptor precursors Photoexcited TiO2 is only weakly reducing (−0.3 eV) and consequently less attention has been given to its role in preparative SCPC with acceptor molecules. In order to carry out such reductive

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• key building block for the synthesis of calix[4]arene. Here, α,ω-bis(p-methoxyphenyl)alkanes 264 were used as starting materials. Compound 264 was treated with acetic anhydride and AlCl3 in nitrobenzene and 1,1,2,2-tetrachloroethane to generate diketone 265 in 58–93% yield. Diketone 265 was then

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

• inert CH-reagents, cycloalkanes, to form a product, which can be subjected to higher oxidation under the conditions of oxidative coupling (Scheme 38). Related oxidative C–O coupling reactions of alkanes with methylarenes and carboxylic acids are discussed in sections 4.1 and 6, respectively. Different

Supercritical carbon dioxide: a solvent like no other

• Jocelyn Peach and
• Julian Eastoe

Beilstein J. Org. Chem. 2014, 10, 1878–1895, doi:10.3762/bjoc.10.196

• solvophilicity in carbon dioxide in comparison to linear alkanes. This in turn led to the formation of w/c microemulsions with increased stability. It is thought that this is due to weaker interactions between surfactant tails as well as lower surfactant affinity to water thus leading to an improved partition

• spherical reverse micellar structures to form rod-like and ellipsoid microemulsions in alkanes, and also interestingly scCO2 systems [40][94][104]. Extensive work by Hatzopoulos et al. has been carried out to investigate further the impacts of hydrotropic salt structure and water level (w) on AOT surfactant

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• series of n-alkanes (C8–C32). Compounds were identified by comparison of mass spectra to database spectra (Wiley 7, NIST 08 and our own created from synthesized reference compounds), by comparison of the retention index data to standards (own database and NIST Chemistry WebBook (2013) [14]) and by

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• a selectivity of 97% [27]. In a subsequent study, the effect of the two hotspot positions on regioselectivity towards cyclic and acyclic alkanes was investigated [28]. Among others, the double mutant F87V/A328F hydroxylated n-octane to 2-octanol with higher regioselectivity (92%) than the wild type

[²H₂₆]-1-epi-Cubenol, a completely deuterated natural product from Streptomyces griseus

• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2841–2845, doi:10.3762/bjoc.9.319

• splitless (60 s valve time) and the carrier gas was He at 1.2 mL min−1. The GC was programmed as follows: 5 min at 50 °C increasing with 5 °C min−1 to 320 °C. Retention indices (I) were determined from a homologous series of n-alkanes (C8–C38). Terpenoids from Streptomyces griseus. Total ion chromatograms

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• the carrier gas was He at 1.2 mL min−1. The GC was programmed as follows: 5 min at 50 °C increasing with 5 °C min−1 to 320 °C. Retention indices (I) were determined from a homologous series of n-alkanes (C8–C38). The mass spectra of the natural compounds X and Y are shown in Figure 2. For comparison

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

• Åsmund Kaupang and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157

• substituted ethylenes, in a case where only C–H insertion is viable, a highly stabilised dirhodium(II) carbenoid shows increased selectivity among the possible C–H insertion partners. For alkanes, the following order of preference is observed: R3CH > R2CH2 > RCH3 [2][74][75][76]. The order of reactivity of

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• experiments support the reversibility of these “rollover” reactions. The highly unsaturated species 55 is still reactive and can coordinate and decompose XMe2 molecules (X = S [128] and O [129]) and dehydrogenate alkanes [130]. Finally

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• reported the efficient air-assisted nitration of alkanes [24] and alkyl side-chain aromatic compounds [25] by nitrogen dioxide and nitric acid, under NHPI catalysis (Scheme 8). Both HNO3 and NO2 are able to promote the formation of PINO according to path (a) and (b) reported in Scheme 9. These initiation

• zeolite, for the oxygenation of a wider range of hydrocarbons [34]. Moreover, the electronic effect of substituents on quinones and on the aromatic ring of NHPI was also investigated. Quinones bearing halogen groups were used in the selective oxidation of alkylarenes, alkenes and alkanes [35], revealing

• hydroxamic acid and O2. NHPI-catalyzed reaction of adamantane under NO atmosphere. Nitration of alkanes and alkyl side-chains of aromatics. Radical mechanism for the nitration of alkanes catalyzed by NHPI. Benzyl alcohols from alkylbenzenes. Catalytic cycle of laccase-NHDs mediator oxidizing system. DADCAQ

Copper-catalyzed aerobic aliphatic C–H oxygenation with hydroperoxides

• Pei Chui Too,
• Ya Lin Tnay and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2013, 9, 1217–1225, doi:10.3762/bjoc.9.138

• (for Table 3, entries 1 and 2) and fragmented ketones 7 (for Table 3, entries 1–4) were observed as minor products. Our next challenge was to develop direct aerobic dioxygenation of alkanes using the present radical strategy. The generation of C-radicals from alkanes at C–H bonds bearing relatively

• could be envisioned that this aerobic C–H bond oxygenation could be combined with the present remote C–H oxygenation with hydroperoxides, presumably resulting in direct formation of 1,4-dioxygenated compounds from nonoxygenated alkanes (Scheme 6). With this hypothesis, alkane 10 bearing a dibenzylic

• direct 1,4-dioxygenation of alkane 10 was demonstrated by using the present method. Further studies will be carried out to develop more robust and efficient catalytic aerobic radical transformations for polyol synthesis from rather simple alkanes. Aliphatic C–H oxidation with amidines and ketimines by