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

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

• Maurizio Fagnoni,
• Stefano Protti,
• Davide Ravelli and
• Angelo Albini

Beilstein J. Org. Chem. 2013, 9, 800–808, doi:10.3762/bjoc.9.91

• ], aliphatic acetals and ketals [16], ethers [17], organostannanes [18][19], organosilanes [20][21][22], aromatics [10][23][24], and even alkanes [25][26][27]. BET (path a') could ensue, thus leading to no chemical change. However, when the D–X•+ intermediate contained a good electrofugal group (such as a

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• ][29][30][31][32][33]. The resulting organomagnesium and organozinc intermediates have versatile reactivity toward various electrophiles to provide multisubstituted alkenes and alkanes. Thus, carbomagnesiation and carbozincation reactions are highly important in organic synthesis. Although

• surely provide powerful routes for functionalized multisubstituted alkenes and alkanes from simple alkynes and alkenes with high regio-, stereo-, and ultimately enantioselectivity. Variation of substrates for carbomagnesiation and carbozincation in this article. Copper-catalyzed arylmagnesiation and

Alternaric acid: formal synthesis and related studies

• Michael C. Slade and
• Jeffrey S. Johnson

Beilstein J. Org. Chem. 2013, 9, 166–172, doi:10.3762/bjoc.9.19

• and the wealth of precedents for single-step desulfurization to alkanes [36][37][38][39][40]. The racemic synthesis of the requisite aldehyde proved straightforward (see Supporting Information File 1). Most importantly, in initial three-component coupling reactions with vinyl nucleophile 4 and silyl

Algicidal lactones from the marine Roseobacter clade bacterium Ruegeria pomeroyi

• Ramona Riclea,
• Julia Gleitzmann,
• Hilke Bruns,
• Corina Junker,
• Barbara Schulz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2012, 8, 941–950, doi:10.3762/bjoc.8.106

• determined from a homologous series of n-alkanes (C8–C32). For compound identification commercially available mass-spectrum libraries were used [26][27]. General synthetic methods: The syntheses of the reference compounds 7/8 and 9/10 were performed by using the same route. In the following paragraphs

Regio- and stereoselective oxidation of unactivated C–H bonds with Rhodococcus rhodochrous

• Elaine O’Reilly,
• Suzanne J. Aitken,
• Gideon Grogan,
• Paul P. Kelly,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2012, 8, 496–500, doi:10.3762/bjoc.8.56

• hydrocarbons, including n-alkanes and isoalkanes, and has been reported to catalyse the terminal hydroxylation of chloroalkanes and long-chain alkenes [13]. It has been suggested that this strain contains an alkane-inducible NADH-dependent hydroxylase that catalyses the oxidation of n-octane to 1-octanol [13

Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium

• Michael Dobmeier,
• Josef M. Herrmann,
• Dieter Lenoir and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 330–336, doi:10.3762/bjoc.8.36

• classic Kiliani protocol and is more applicable to organic synthesis. Results and Discussion Initial investigations focused on simple benzylic alcohols (Table 1, entries 1–3), which were converted in high to quantitative yields into the corresponding alkanes. Carbonyl groups or amides in a benzylic

• . Benzylic alcohols were converted in good to high yields to alkanes with increasing reactivity in the order primary (2 h) < secondary (0.5–1 h) < tertiary alcohol (15–30 min); carbonyl groups and ethers were tolerated. Diethyl tartrate was converted into diethyl succinate under the reaction conditions given

• . Alcohols other than those that were benzylic or α to carbonyl groups were not converted into the corresponding alkanes, and the reaction stopped at the iodoalkanes (Table 3). The reactivity follows the order of primary < secondary < tertiary alcohols, as expected for an SN1 reaction. The reduction

The volatiles of pathogenic and nonpathogenic mycobacteria and related bacteria

• Thorben Nawrath,
• Georgies F. Mgode,
• Bart Weetjens,
• Stefan H. E. Kaufmann and
• Stefan Schulz

Beilstein J. Org. Chem. 2012, 8, 290–299, doi:10.3762/bjoc.8.31

• mL min–1 (HP-6890) or 1.2 mL min−1 (Agilent 7890A). Retention indices (I) were determined from a homologous series of n-alkanes (C8–C35) [19]. Identification of compounds was performed by comparison of mass spectra to the Wiley-6 Library, NIST 07, and the Essential Oils Library (Massfinder) and gas

Biocatalytic hydroxylation of n-butane with in situ cofactor regeneration at low temperature and under normal pressure

• Svenja Staudt,
• Christina A. Müller,
• Jan Marienhagen,
• Christian Böing,
• Stefan Buchholz,
• Ulrich Schwaneberg and
• Harald Gröger

Beilstein J. Org. Chem. 2012, 8, 186–191, doi:10.3762/bjoc.8.20

• n-alkanes, which proceeds in the presence of a P450-monooxygenase advantageously at temperatures significantly below room temperature, is described. In addition, an enzymatic hydroxylation of the “liquid gas” n-butane with in situ cofactor regeneration, which does not require high-pressure

• nonfunctionalized alkanes represents one of the most challenging types of reactions that organic chemists currently face [1][2][3]. A particular challenge in this field is the functionalization of volatile n-alkanes, which are present as gases under ambient conditions. A short n-alkane molecule that fulfils these

• within the following 16 h. In one experiment at 0 °C the work-up was directly carried out without a warm-up of the reaction mixture. As a P450-monooxygenase, the 19A12-mutant of the BM-3 enzyme was used, since this enzyme was reproted to be suitable for short-chain n-alkanes [8]. Once again, a glucose

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• alkanes with acetyl cation (CH3CO+) salts in HF·BF3. These studies showed that acetyl cation (CH3CO+) salts were capable of abstracting hydride from the isoalkanes when the reactions were performed in superacdic media. Studies by Olah and coworkers had shown [7] that acetyl cation salts do not react with

• nucleophiles, such as arenes and alkanes. This has led to the development of several new synthetic transformations leading to the functionalization of alkanes. Moreover, superelectrophiles have been used to prepare a wide variety of functionalized arenes. Many types of Friedel–Crafts type reactions have been

• this study, protolysis steps with alkanes often leads to β-scission reactions (cleavage of the alkane-based carbocations). This reaction path is not observed with superelectrophiles 70, 71, or 73, because these types of cleavage reactions would generate dicationic species with the cationic charges in

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, C_nH_n and closo-boranes [B_xH_x]²⁻

• Michael J. McGlinchey and
• Henning Hopf

Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30

• structure). Now, every deltahedron has a reciprocal polyhedron in which each triangular face has become a vertex linked to three neighbors; this is precisely the criterion that has to be satisfied by alkanes of the CnHn type. To illustrate this inverse polyhedral relationship between closo-boranes, [BxHx]2

• contributions to this area [33]. Currently unknown polyhedranes, CnHn, n = 12, 14, 16, 18 After this short overview of the successful syntheses of several polycyclic alkanes, CnHn, where n = 4, 6, 8, 10 and 20, we now turn to the remaining unknown polyhedranes for which n = 12 (octahedrane, 12), n = 14

Expanding the gelation properties of valine-based 3,5-diaminobenzoate organogelators with N-alkylurea functionalities

• Hak-Fun Chow and
• Chin-Ho Cheng

Beilstein J. Org. Chem. 2010, 6, 1015–1021, doi:10.3762/bjoc.6.114

• gelating power in aromatic solvents. However, they are poor organogelators in non-aromatic solvents such as alkanes, alcohols, acetone, acetonitrile and DMSO. In order to further expand their gelating power in other solvents, we decided to further modify the appending Cbz groups with other functionalities

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• ) polyhalogenofluoro alkanes as partial fluorinated alkylating agents generates the corresponding sulfides which are appropriate precursors for subsequent conversion to perfluoroalkyl thioethers. For example, α,α-difluoro polyhalogenoalkyl sulfides and α,α-dichlorotrifluoroethyl sulfide can be obtained by reaction of

The C–F bond as a conformational tool in organic and biological chemistry

• Luke Hunter

Beilstein J. Org. Chem. 2010, 6, No. 38, doi:10.3762/bjoc.6.38

• fluoroalkane” (e.g. 54, Figure 12), which is conceptually intermediate between alkanes and perfluoroalkanes [37]. Multi-vicinal fluoroalkanes are interesting systems for studying stereoelectronic effects such as the gauche effect and they also have potential applications in materials science, for example, as