Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• -hexyne (67%, 1) compared to 1-heptyne (ca. 90%, 2) under analogous conditions (30% conversion, room temperature, 1 bar H2, hydrocarbon solvent), hydrogenation experiments were carried out using different catalysts, namely 1% Pd@Al2O3 for 1 [121] and 2% Pd@Al2O3 for 2 [126], and reactor setups. Therefore

Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

• Loïc Pantaine,
• Vincent Humblot,
• Vincent Coeffard and
• Anne Vallée

Beilstein J. Org. Chem. 2017, 13, 648–658, doi:10.3762/bjoc.13.64

• developed on gold surfaces. One of the main reasons could be explained by the necessity to work under mild conditions; it is well known that the energy of interaction between sulfur and gold is in order of 45–50 kcal/mol and the desorption of the thiols can occur at about 70 °C in hydrocarbon solvent [53

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

• Lukas J. Patalag and
• Daniel B. Werz

Beilstein J. Org. Chem. 2016, 12, 2739–2747, doi:10.3762/bjoc.12.270

• chain [15]. Their slim shape mimics the natural geometry of a saturated hydrocarbon chain and should therefore only lead to minimal disturbances [16]. Nevertheless, we found that their stability with respect to both, oxygen and strong laser beams, is relatively low. The design of novel fluorescent fatty

• proved to be the method of choice to access the desired structures, which vary only in the grade of unsaturation while the length of their hydrocarbon chain is maintained. The absorption properties were thus modulated by the number of double bonds ranging from λAmax = 374 nm (one double bond) to λAmax

A direct method for the N-tetraalkylation of azamacrocycles

• Andrew J. Counsell,
• Angus T. Jones,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239

• reasonable (71% for the tetra n-propyl derivative, 50% for tetra-n-dodecyl), but the scope was not explored beyond these two examples [33]. Fricke et al. have generated cyclen derivatives N-tetraalkylated with long hydrocarbon chains (unbranched C8, C12 and C18 alkyl chains), using n-BuLi to irreversibly

• N-tetraalkylate cyclam efficiently with small hydrocarbon chains (C2–C4) and also prepare the tetramethoxyethyl and -ethoxyethyl derivatives, all in excellent yields (83–90%) [39]. We sought a simple route to cyclam and cyclen derivatives N-tetraalkylated with propargyl (CH2C≡CH) and aromatic groups

A new paradigm for designing ring construction strategies for green organic synthesis: implications for the discovery of multicomponent reactions to build molecules containing a single ring

• John Andraos

Beilstein J. Org. Chem. 2016, 12, 2420–2442, doi:10.3762/bjoc.12.236

• for a given molecular formula of a hydrocarbon [127][128], and parameterizing chemical properties with topological indices [129][130][131]. However, none of these integer applications involves partitioning of those integers. In this work we apply the concept of integer partitioning to retrosynthetic

• each partition type. Hence, the construction of hydrocarbon skeletons, containing no pivoting nucleophilic or electrophilic atoms, yields the highest range of possible assemblies and hence the greatest opportunities for creativity and novelty in synthesis design. This explains why such target compounds

A detailed view on 1,8-cineol biosynthesis by Streptomyces clavuligerus

• Jan Rinkel,
• Patrick Rabe,
• Laura zur Horst and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 2317–2324, doi:10.3762/bjoc.12.225

• a RY dimer [9]. The substrate is ionised by diphosphate abstraction and the resulting allyl cation undergoes a domino reaction via a series of cationic intermediates and a final deprotonation or attack of water to yield a terpene hydrocarbon or alcohol. This reaction cascade proceeds in a

Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction

• Ángel Cantín,
• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208

• converted into a variety of liquid hydrocarbon fuels and fuel additives [11][12]. Catalysis is considered as one of the foundational pillars of green chemistry. Catalysis often reduces the energy requirements, permits the use of renewable feedstocks and less toxic reagents. Moreover, in most cases yields

Mechanistic investigations on six bacterial terpene cyclases

• Patrick Rabe,
• Thomas Schmitz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1839–1850, doi:10.3762/bjoc.12.173

• relative (94% identical sites). Another terpene synthase from Chitinophaga pinensis DSM 2588 (accession number WP_012792334) converted FPP into a terpene hydrocarbon 5, identified as γ-cadinene by GC–MS [32], besides traces of α- and δ-cadinene (Figure S1, Supporting Information File 1), while no reaction

• incubated with FPP to yield a sesquiterpene hydrocarbon as single product (Figure S1, Supporting Information File 1) whose NMR data (Table 3) matched those reported for (E)-β-caryophyllene (6) [50]. The optical rotary power was determined as [α]D24 = −14.0 (c 0.13, CH2Cl2), pointing to the same absolute

Mutagenic activity of quaternary ammonium salt derivatives of carbohydrates

• Barbara Dmochowska,
• Karol Sikora,
• Anna Woziwodzka,
• Jacek Piosik and
• Beata Podgórska

Beilstein J. Org. Chem. 2016, 12, 1434–1439, doi:10.3762/bjoc.12.138

• ammonium salt (QAS) derivatives of glucopyranosides with an elongated hydrophobic hydrocarbon chain. The new N-[6-(β-D-glucopyranosyloxy)hexyl]ammonium bromides and their O-acetyl derivatives were analyzed via 1H and 13C NMR spectroscopy. The mutagenic activity of the newly synthesized QAS was investigated

• to previously described derivatives with two carbon atom spacers dividing the sugar moiety and the ammonium group [22]. Here, we synthesized compounds with a long hydrocarbon chain (containing six carbon atoms), which will enable us to analyze the influence of the distance between QASs and the sugar

• containing a carbohydrate moiety with a two-carbon atom linker in the Vibrio harveyi bioluminescence assay. Here, we provide evidence for the mutagenic potential of corresponding QAS–carbohydrate derivatives with a longer, six-carbon atom linker. This suggests that the introduction of a longer hydrocarbon

Unusual traits of cis and trans-2,3-dibromo-1,1-dimethylindane on the way from 1,1-dimethylindene to 2-bromo-, 3-bromo-, and 2,3-dibromo-1,1-dimethylindene

• Rudolf Knorr,
• David S. Stephenson,
• Ernst Lattke,
• Petra Böhrer and
• Jakob Ruhdorfer

Beilstein J. Org. Chem. 2016, 12, 1178–1184, doi:10.3762/bjoc.12.113

• interchange reaction of 7 in hexane as the solvent with n-butyllithium (n-BuLi) ocurred predominantly at the 3-position of 7 with formation of 2-bromo-3-lithio-1,1-dimethylindene (10, Scheme 3). In the absence of cycloalkanes or benzene from the hydrocarbon solvent, rather concentrated mixtures of 7 and n

• . 2-Bromo-1,1-dimethylindene (4). A sample of contaminated 2,3-dibromo-1,1-dimethylindene (7, 8.43 g, 27.7 mmol) in pentane (5.0 mL) was treated with n-BuLi (ca. 40 mmol) in hexane (35 mL) at −70 °C under argon gas cover. Since this reaction was run in an acyclic, saturated hydrocarbon as the solvent

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

• “ [12]. Organic nitrates are important in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. It is generally accepted that transport models should include representation of organic aerosols derived from the reaction of monoterpenes with nitrate radicals. With this in mind

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

• rhodium complex (S)-23 with good to excellent enantioselective control (Scheme 5) [41]. The best results were observed when the reaction was carried out at room temperature. A wide range of substituent groups were evaluated at para position of the aryldiazoacetate aromatic ring. The cyclic hydrocarbon

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

• , “slab of hydrocarbon”. Hence this example of selective, remote functionalization of the steroid framework was captivating. This captivation was itself pivotal to my career path, and it is a constant reminder to me (and hopefully young practitioners I’ve told this story to) how important it is to keep

• more specifically, the subset of this class of enzymes that play an important role in steroidogenesis. How does the body synthesize all those steroid hormones? How does Nature carry out remote functionalization on these slabs of hydrocarbon? The answer of course involves a heme-cofactor and an

• state. If (for fun) this guest is treated as an ideal gas, then the pressure within the capsule can be calculated to be roughly 100 atmospheres. Other hydrocarbon gases could be encapsulated. For example, methane and ethane formed 1:1 host–guest complexes, and propane formed a 2:2 complex. Interestingly

Biosynthesis of α-pyrones

• Till F. Schäberle

Beilstein J. Org. Chem. 2016, 12, 571–588, doi:10.3762/bjoc.12.56

• and by inducing the so-called aryl hydrocarbon receptor, apoptosis is mediated by inducing cytochrome P450 1A1 [25]. For alternariol 9-methyl ether (19) and the graphislactone A (21) cytotoxic effects against the human cancer cell line SW1116 with IC50 values between 8.5 and 21 μg/mL were reported [26

Dynamic behavior of rearranging carbocations – implications for terpene biosynthesis

• Stephanie R. Hare and
• Dean J. Tantillo

Beilstein J. Org. Chem. 2016, 12, 377–390, doi:10.3762/bjoc.12.41

• a striking range of molecular architectures, varying in size and complexity (Figure 1) [1][2][3][4][5]. Some terpenes sport multiple stereogenic centers and multiple carbocyclic rings. These complex hydrocarbon frameworks are derived, however, from simple precursors lacking stereogenic centers and

Regioselective palladium-catalyzed ring-opening reactions of C1-substituted oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylates

• Michael Edmunds,
• Mohammed Abdul Raheem,
• Rebecca Boutin,
• Katrina Tait and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 239–244, doi:10.3762/bjoc.12.25

• bridgehead carbon appears to impact the reactions’ outcome by hindering access to the site of carbo-palladation. SiMe3 gave a moderate yield of 64% (Table 3, entry 4). The silicon–carbon bond is longer than carbon–carbon bonds, making TMS less bulky than its hydrocarbon counterparts. Both of the electron

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

• of steroids, to determining hydrocarbon pKa values using electrochemistry. The lesson learned, and one I tried to put into practice in my independent career (see below), is that it is very much possible to run a research group focused in quite different areas of chemistry. With an NSF-NATO

Facile synthesis of 4H-chromene derivatives via base-mediated annulation of ortho-hydroxychalcones and 2-bromoallyl sulfones

• Srinivas Thadkapally,
• Athira C. Kunjachan and
• Rajeev S. Menon

Beilstein J. Org. Chem. 2016, 12, 16–21, doi:10.3762/bjoc.12.3

• . Polycyclic aromatic hydrocarbon frameworks (naphthalene and anthracene rings) as well as a representative heterocyclic ring (furan) may be incorporated into the 4H-chromene skeleton product by using chalcones (7c, 7d, and 7e, respectively) functionalized with these moieties. Disappointingly, attempts to

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• ·TM-βCD in water. As can be seen from Table 3, quite similar values were obtained in diiodomethane for the reference 3 and 3·TM-γCD polyrotaxane. These results are typical of surfaces covered with a close packing of hydrocarbon chains [55]. In contrast, a lower θ value is observed for 3·TM-βCD. Such

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

• ) are established catalysts of C–O bond formation, oxidising hydrocarbon substrates via hydroxylation, epoxidation and dihydroxylation pathways. Herein we report the capacity of these catalysts to promote C–N bond formation, via allylic amination of alkenes. The combination of N-Boc-hydroxylamine with

• iron-catalysed hydrocarbon oxidation using systems inspired by the non-heme iron-dependent enzyme family [42][43][44][45][46][47], we have investigated the capacity of iron complexes of simple tetramine ligands to promote the reaction between an alkene and N-Boc-hydroxylamine. Herein we report that

• intermediate. Conclusion FeTPA (4) and FeBPMEN (5) are established catalysts for the hydroxylation, dihydroxylation and epoxidation of hydrocarbon substrates [48][58][59][60]. In this study we have shown that they can also catalyse the allylic hydroxyamination of alkenes with N-Boc-hydroxylamine. Mechanistic

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

• low cost starting materials [1]. One of the most attractive reagents in terms of cost and environmental impact for hydrocarbon oxidation is oxygen in the presence of a catalyst. In this context enzymatic oxidations are attractive, in particular cytochrome P450 monooxygenases (P450s or CYPs) due to

Antioxidant potential of curcumin-related compounds studied by chemiluminescence kinetics, chain-breaking efficiencies, scavenging activity (ORAC) and DFT calculations

• Adriana K. Slavova-Kazakova,
• Silvia E. Angelova,
• Timur L. Veprintsev,
• Petko Denev,
• Davide Fabbri,
• Maria Antonietta Dettori,
• Maria Kratchanova,
• Vladimir V. Naumov,
• Aleksei V. Trofimov,
• Rostislav F. Vasil’ev,
• Giovanna Delogu and
• Vessela D. Kancheva

Beilstein J. Org. Chem. 2015, 11, 1398–1411, doi:10.3762/bjoc.11.151

• ), zingerone (3), (2Z,5E)-ethyl 2-hydroxy-6-(4-hydroxy-3-methoxyphenyl)-4-oxohexa-2,5-dienoate (4), ferulic acid (5) and their corresponding C2-symmetric dimers 6–9. Four models were applied: model 1 – chemiluminescence (CL) of a hydrocarbon substrate used for determination of the rate constants (kA) of the

• were applied: model 1 – chemiluminescence of a hydrocarbon substrate used for determination of the rate constants (kA) of the reactions of the antioxidants with peroxyl radicals (RO2•); model 2 – lipid autoxidation used for assessing the chain-breaking antioxidant efficiency and reactivity; model 3

• = 15.6 Hz, 2H); 13C NMR δ 14.04, 55.96, 62.44, 100.58, 109.76, 115.11, 120.59, 123.88, 126.94, 143.74, 146.99, 148.80, 162.22, 172.98, 185.95; Anal. calcd for C30H30O12: C, 61.85; H, 5.19; found: C, 61.99; H, 5.28. Model 1: Chemiluminescence with model hydrocarbon ethylbenzene The chemiluminescence time

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• Lebensmittelsicherheit (BVL), Messeweg 11/12, D-38104 Braunschweig, Germany 10.3762/bjoc.11.139 Abstract The chemical behavior of various oligoenes 2 has been studied. The catalytic hydrogenation of diene 3 yielded monoene 4. Triene 7 was hydrogenated to diene 8, monoene 9 and saturated hydrocarbon 10. Bromine addition

• extend the packing, again by translation, to layers parallel to the bc plane at z ≈ ¼ and z ≈ ¾. The hydrogenation mixture yielded no evidence for the formation of a 1,2-adduct (5) or of the fully saturated hydrocarbon 6. In fact, the primary adduct 4 was inert towards hydrogen even under very harsh

• . Even under mild conditions (Pd/C, EtOH/hexane, room temp.) it is readily reduced (Scheme 3). After 5 minutes of hydrogenation, three products were detected: the 1,6-adduct 8, a diene (main product); the mono olefin 9; and the fully saturated hydrocarbon 10. When the reaction time was increased, the

The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 437–445, doi:10.3762/bjoc.11.50

• start with the parent hydrocarbon [2.2]paracyclophane (12), convert this to the dibromide 13, metalate it to the corresponding dilithio derivative, from which 14 is finally obtained by a CO2 quench [25][26]. On treatment of 14 with oxalyl chloride in anhydrous dichloromethane in the presence of

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• reaction, it dimerized to the bis-indene derivative 17, rather than providing the tetramethyl derivative of 4, the hydrocarbon 14. In a second approach, indan-1-one (18) was dimerized to the conjugated enedione 21 through the bis-1-indene dimer 19. All attempts to methylenate 21 failed, however. When 19

• direct conjugation, whereby a third such system is excluded from interaction [3]. Typical examples are 2-vinyl-buta-1,3-diene ([3]dendralene, 3-methylene-penta-1,4-diene), benzophenone or urea. Whereas the hydrocarbon parent systems, the [n]dendralenes, have long been a neglected class of oligoenes [4

• . Results and Discussion Our first attempt to prepare hydrocarbon 4 started from indene (6, Scheme 2). Epoxidation with m-chloroperbenzoic acid (MCPBA) according to a literature method [15] yielded the epoxide 7 in meager yields (Scheme 2). The methylation of 7 to 8 was achieved by the treatment with