Biosynthesis of rare hexoses using microorganisms and related enzymes

• Zijie Li,
• Yahui Gao,
• Hideki Nakanishi,
• Xiaodong Gao and
• Li Cai

Beilstein J. Org. Chem. 2013, 9, 2434–2445, doi:10.3762/bjoc.9.281

• sanctum seeds) and investigated their synthetic application for L-glucose production from D-sorbitol (Scheme 13) [83][84]. Catalase could degrade the hydrogen peroxide byproduct and increase the conversion by removing the inhibition effect of hydrogen peroxide toward galactose oxidase and regenerating

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• -step sequence yielded azetidine 107. After oxidation with hydrogen peroxide, the resulting N-oxide cleanly underwent a [1,2]-Meisenheimer rearrangement upon heating in tetrahydrofuran. The so-formed azocine 108 was converted to amine 109 by hydrogenolysis of the N–O bond. Amide formation with acid

Integrating reaction and analysis: investigation of higher-order reactions by cryogenic trapping

• Skrollan Stockinger and
• Oliver Trapp

Beilstein J. Org. Chem. 2013, 9, 1837–1842, doi:10.3762/bjoc.9.214

• reactions, so that the reaction kinetics can be investigated under comparable reaction conditions. So far, we investigated only first-order or pseudo-first-order reactions, where, for example, one reactant is used as a carrier gas, i.e., hydrogen in hydrogenation reactions or hydrogen peroxide as oxidant

A practical synthesis of long-chain iso-fatty acids (iso-C₁₂–C₁₉) and related natural products

• Mark B. Richardson and
• Spencer J. Williams

Beilstein J. Org. Chem. 2013, 9, 1807–1812, doi:10.3762/bjoc.9.210

• triethylsilane and BF3·Et2O [53], affording 11. Oxidative cleavage of 11 with KMnO4/Bu4NBr [54] afforded iso-C12 acid 1. Alternatively, anti-Markovnikov hydration of 11, using I2/NaBH4 then hydrogen peroxide [55], afforded the alcohol 12, and oxidation of 12 with KMnO4/Bu4NBr afforded iso-C13 acid 2

The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow

• Kimberley A. Roper,
• Malcolm B. Berry and
• Steven V. Ley

Beilstein J. Org. Chem. 2013, 9, 1781–1790, doi:10.3762/bjoc.9.207

• , dibenzoyl peroxide (9) was then added and the temperature maintained at 50 °C until this had completely dissolved. The mixture was then transferred to a glass column, the ends sealed with custom-made PTFE end pieces and heated to 92 °C for 48 hours using a Vapourtec R4 heating unit. This protocol can be

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• cycloalkanes were prepared based on a radical substitution of cyclohydrocarbon units to (E)-β-nitrostyrenes by using the radical initiator benzoyl peroxide [59]. Recently, the Liu group developed a copper-catalyzed decarboxylative coupling of vinylic carboxylic acids with simple alcohols and ethers in high

• ) in the presence of iron(II) chloride tetrahydrate (20 mol %) and 2.0 equiv of di-tert-butyl peroxide (DTBP) as the oxidant at 120 °C under nitrogen, which provided the expected (E)-(2-cyclohexylvinyl)benzene (3a), but in a moderate 54% yield (Table 1, entry 1). The use of aqueous TBHP as oxidant

• ) under a nitrogen atmosphere. Cycloalkane (2.0 mL, 15–25 mmol) and DTBP (di-tert-butyl peroxide, 0.6 mmol, 113 μL) were added under a nitrogen atmosphere and the resulting reaction mixture was stirred at 120 °C for 24 h. After cooling to room temperature and removal of volatiles, the products were

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

• Yuta Nishina,
• Bunsho Ohtani and
• Kotaro Kikushima

Beilstein J. Org. Chem. 2013, 9, 1663–1667, doi:10.3762/bjoc.9.190

• azobisisobutyronitrile or benzoyl peroxide as radical initiators are typical conditions for Wohl–Ziegler bromination [9][10][11][12] and are widely used for the bromination of benzylic and allylic positions, despite the need for heating and the generation of equimolar amounts of waste. To avoid these drawbacks, several

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• hydrogels become soluble by reduction of disulfide to mercaptanes by use of dithiothreitol (DTT), tris(2-carboxyethyl)phosphine (TCEP) or cysteamine, respectively. The soluble polymeric system can be cross-linked again by using oxygen or hydrogen peroxide under basic conditions. The redox-responsive polymer

Re₂O₇-catalyzed reaction of hemiacetals and aldehydes with O-, S-, and C-nucleophiles

• Wantanee Sittiwong,
• Michael W. Richardson,
• Charles E. Schiaffo,
• Thomas J. Fisher and
• Patrick H. Dussault

Beilstein J. Org. Chem. 2013, 9, 1526–1532, doi:10.3762/bjoc.9.174

• peroxide or hydroperoxides [11][12], intramolecular displacements of reversibly formed hemiacetals and allylic alcohols [8][13], displacement of resonance-activated alcohols with electron-poor nitrogen nucleophiles [14], and a synthesis of homoallylated amines from condensation of carbonyl groups with an

• moderate yield of a new hydroperoxyacetal. The exchange reaction was observed in several solvents (e.g., CH2Cl2, 1,2-dichloroethane) but was most efficient in acetonitrile. The alkoxide exchange was accompanied by much slower exchange of the peroxide; for example, prolonged reaction (>24 h) of acetal 26 in

• hydroperoxide (which would presumably lead to heterolytic fragmentation) and activation of the peroxide C–O was clearly disfavored relative to activation of the alkoxide C–O bond. Rapid alkoxide metathesis was also observed in the presence of a strong Brønsted acid. Our observations suggest that the seeming

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

• role of these initiators in promoting the formation of PINO, performing several selective transformations under aerobic or anaerobic conditions. The combination of NHPI with tiny amounts of dibenzoyl peroxide (BPO) under an atmosphere of argon led to the hydroacylation of simple alkenes by addition of

Homolytic substitution at phosphorus for C–P bond formation in organic synthesis

• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 1269–1277, doi:10.3762/bjoc.9.143

•  15) [42]. Photolysis of the esters in the presence of white phosphorus followed by oxidation with hydrogen peroxide yields alkylphosphonic acid. The efficient phosphination would stem from the highly strained structure and the weak P–P bonds of white phosphorus. After 13 years of silence, radical

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

• molecular O2 to give peroxy radical III. Probably further reaction of III with Cu(I) species gives Cu(II)-peroxide IV, which undergoes fragmentation to give aldehyde V [16][17][18], which in turn cyclizes to afford hemiacetal 2a. Protonation of Cu(II)-peroxide IV followed by the reduction of the resulting

Selective copper(II) acetate and potassium iodide catalyzed oxidation of aminals to dihydroquinazoline and quinazolinone alkaloids

• Matthew T. Richers,
• Chenfei Zhao and
• Daniel Seidel

Beilstein J. Org. Chem. 2013, 9, 1194–1201, doi:10.3762/bjoc.9.135

• was heated under reflux in an oxygen atmosphere and in the presence of 20 mol % of CuCl2, 2 was only observed in trace amounts; deoxyvasicinone (4) and peroxide 8 were also formed as products. Switching the catalyst to Cu(OAc)2 led to a 15% yield of the desired product 2, but the process was still

• promote the full oxidation of aminal 21 to deoxyvasicinone (4) were met with disappointment, with yields of 4 for these conditions reaching a maximum of around 40% (Table 3). In most cases, peroxide 8 was observed as a major side product. The Cu/TEMPO/DABCO catalyst system employed by Han et al. [35] for

• Reddy’s conditions, in which piperidine was added directly to the solution after 36 hours instead of the removal of solvent from the intermediate peroxide beforehand, resulted in identical yields. Using the optimized conditions, a range of different quinazolinones were synthesized (Table 4). In general

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• have studied flow reactions, including the decomposition of hydrogen peroxide, oxidation of organic dyes, carbon–carbon coupling, and conversion of formic acid to hydrogen (H2) and carbon dioxide (CO2), using catalytic tubular reactors [10][11][12][13]. p-Aminophenol is an important intermediate

• acid (HNO3, 60%) and hydrogen peroxide (H2O2, 30%) were purchased from Wako Pure Chemical Industries Ltd. and were used without further purification. Fabrication of tubular reactors A double-layered tube (o.d. 1.6 mm, i.d. 0.5 mm, length 100 cm) composed of Inconel 625 and titanium (Ti) inner layer

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• reaction of PhCCl3 and (EtO)3P at 120–140 °C produced 1,2-diphenyl-1,1,2,2-tetrachloroethane [13]. The early work reported that the trisphosphonate PhC(PO3Et2)3 was formed from triethyl phosphite and dibenzoyl peroxide when reagents were boiled under reflux in chloroform, but proof of the trisphosphonate

• intermediate with hydrogen peroxide in tetrahydrofuran [26]. Mixed ethyl/isopropyl trisphosphonate ester 9 has been prepared by treatment of the bisphosphonate 7 with diethyl chlorophosphite and sodium hexamethyldisilazane, and subsequent oxidation of the phosphinate intermediate 8 with iodine in pyridine–THF

• treatment of trisphosphonate salt 38 with a mixture of hydrogen peroxide in trifluoroacetic acid (Scheme 22). An alternative and more efficient synthesis of methylidynetrisphosphonic acid uses a transsilylation of hexaalkyl trisphosphonate 9 followed by hydrolysis [27]. Synthesis of

NHC-catalysed highly selective aerobic oxidation of nonactivated aldehydes

• Lennart Möhlmann,
• Stefan Ludwig and
• Siegfried Blechert

Beilstein J. Org. Chem. 2013, 9, 602–607, doi:10.3762/bjoc.9.65

• H2O2 as the terminal oxidation agent instead of O2 under nitrogen atmosphere was carried out for the NHC-catalysed oxidation of 4-nitrobenzaldehyde to 4-nitrobenzoic acid. It revealed that the peroxide was capable of effecting the oxidation as well providing comparable conversion. Conclusion In summary

Complete σ* intramolecular aromatic hydroxylation mechanism through O₂ activation by a Schiff base macrocyclic dicopper(I) complex

• Albert Poater and
• Miquel Solà

Beilstein J. Org. Chem. 2013, 9, 585–593, doi:10.3762/bjoc.9.63

• pathway for the overall intramolecular aromatic hydroxylation, i.e., from the initial O2 reaction with the dicopper(I) species to first form a CuICuII-superoxo species, the subsequent reaction with the second CuI center to form a μ-η2:η2-peroxo-CuII2 intermediate, the concerted peroxide O–O bond cleavage

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• formation of the amidyl radical in this case calls for a different precursor and does not involve a stannane reagent. The sequence is triggered by the attack of undecyl radicals on thiosemicarbazone 12. Undecyl radicals arise from the thermal homolysis of lauroyl peroxide and decarboxylation. The lauroyl

• peroxide must be used in stoichiometric amounts, for it is required to oxidise the intermediate cyclohexadienyl radical 13 into its corresponding cation and thence into intermediate 14 by rapid loss of a proton. A faster access to complexity is obtained when intermolecular steps are also involved. This

• well as simple addition product 40 are thus obtained in good combined yield (Scheme 9). The latter may be converted into the same mixture of 41a and 41b by further treatment with peroxide. In practice, however, it is more convenient to subject adduct 40 separately to a reductive double cyclisation to

New enzymatically polymerized copolymers from 4-tert-butylphenol and 4-ferrocenylphenol and their modification and inclusion complexes with β-cyclodextrin

• Adam Mondrzyk,
• Beate Mondrzik,
• Sabrina Gingter and
• Helmut Ritter

Beilstein J. Org. Chem. 2012, 8, 2118–2123, doi:10.3762/bjoc.8.238

• phenols in water/organic-solvent systems in the presence of hydrogen peroxide. In recent studies it was demonstrated that several para-substituted phenols, i.e., 4-tert-butylphenol, can be polymerized with HRP in high yield and relatively high molecular weights [13]. Also several polyphenols with further

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• placed into a reaction flask containing the chromophoric substrate. This flask is usually standard Pyrex glassware. The solution is normally degassed to remove oxygen in order to diminish the possibility of quenching and other reactions, such as peroxide formation (conveniently achieved with a long

• employed in the synthesis of a range of compounds of commercial interest including fragrances and pharmaceuticals. One major disadvantage of using this reaction on a large scale is the potential for fires or detonation of accumulating peroxide products. Other disadvantages include inefficient irradiation

• peroxide product present at any one time, and this can be reduced immediately upon leaving the reactor. The smaller reactor volumes involved in flow chemistry also mean that irradiation is efficient and hence that the singlet oxygen generated can react within its short lifetime. Falling-film microreactors

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• at the 3-indolyl position, yielding products 1. Conversely, the use of dioxane with the addition of acetic acid as a polar coordinating co-solvent in the presence of tert-butyl benzoyl peroxide, directs the selectivity in favor of the C-2 substituted indoles 2. It should be noted that the same

Enantioselective total synthesis of (R)-(−)-complanine

• Krystal A. D. Kamanos and
• Jonathan M. Withey

Beilstein J. Org. Chem. 2012, 8, 1695–1699, doi:10.3762/bjoc.8.192

• ). Although a number of acyloxylations have been reported, the direct catalytic asymmetric acyloxylation of aldehydes has only been recently realized [6][7]. Thus, the asymmetric benzoylation of aldehydes, according to the method of Tomkinson [7], was attempted. Utilizing benzoyl peroxide in the presence of

Reactions of nitroxides XIII: Synthesis of the Morita–Baylis–Hillman adducts bearing a nitroxyl moiety using 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl as a starting compound, and DABCO and quinuclidine as catalysts

• Jerzy Zakrzewski

Beilstein J. Org. Chem. 2012, 8, 1515–1522, doi:10.3762/bjoc.8.171

• of 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (3) on the reaction course was observed. Experimental General: 2,2,6,6-Tetramethyl-4-hydroxypiperidin-1-oxyl (1) was synthesized by the oxidation of 2,2,6,6-tetramethyl-4-piperidinol with 30% hydrogen peroxide (76.5% yield, mp 71–73 °C), according

Synthesis of compounds related to the anti-migraine drug eletriptan hydrobromide

• Suri Babu Madasu,
• Nagaji Ambabhai Vekariya,
• M. N. V. D. Hari Kiran,
• Badarinadh Gupta,
• Aminul Islam,
• Paul S. Douglas and
• Korupolu Raghu Babu

Beilstein J. Org. Chem. 2012, 8, 1400–1405, doi:10.3762/bjoc.8.162

• deacetylation reaction. Eletriptan N-oxide isomers 3 and 4 are possible contaminants that can be formed by oxidation in air. These compounds were prepared by oxidation of eletriptan (14) with aqueous hydrogen peroxide (~50%, w/w) in the presence of catalytic amounts of ammonium molybdate. The isomers 3 and 4

• were separated by preparative HPLC and confirmed by 1H NMR spectroscopy [13][14] (Scheme 3). The combined contamination by 3 and 4 was 0.05–0.25% in eletriptan hydrobromide. Formation of this impurity can be controlled by using peroxide-free solvents during the final stage of synthesis. Impurity 5 is

• (80–85 °C) in the presence of peroxide in aqueous acetonitrile. It was also observed that only 4.5% of this impurity was formed when 10% (w/w) hydrogen peroxide was used. However, this impurity was formed at 40–60%, when 30% (w/w) hydrogen peroxide used. This impurity was identified by LC–MS and