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

• . Dichloromethane and acetonitrile were dried over calcium hydride. Acetonitrile was degassed using three freeze–thaw cycles when it was to be used in an atmosphere of argon. Methanol (MeOH) was dried over magnesium methoxide. Alkenes used in allylic amination reactions were passed through a micro-column of neutral

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• prepared by regioselective reduction of the carbonyl group, silylation of the resulting alcohol and further reduction of the enone moiety. An ensuing transetherification of alcohol 59 with ethyl vinyl ether gave an allyl vinyl ether, which underwent a magnesium perchlorate-promoted [1,3]-sigmatropic

• oxolane bridge between C1 and C7. Hajos–Parrish diketone (107) [39] served as the starting material for the preparation of key intermediate 112. Selective reduction of the ketone and silylation of the resulting alcohol furnished enone 108. α-Carboxylation of the enone with magnesium methyl carbonate and a

• ) led to opening of the oxolane ring and afforded tricycle 113 which features the carbon framework of structurally related umbellacetal (114). Gratifyingly, when magnesium bromide and ethanethiol were used as a mild alternative for the cleavage of the MOM ether, the xenibellol core could be obtained

Efficient synthetic protocols for the preparation of common N-heterocyclic carbene precursors

• Morgan Hans,
• Jan Lorkowski,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2015, 11, 2318–2325, doi:10.3762/bjoc.11.252

• this condensation in dichloromethane containing formic acid as a catalyst and anhydrous magnesium sulfate as a dehydrating agent. We found this procedure difficult to reproduce. Moreover, a rather tedious work-up was required to separate and to purify the product. Inspired by a report from Cole and co

Synthesis of constrained analogues of tryptophan

• Elisabetta Rossi,
• Valentina Pirovano,
• Marco Negrato,
• Giorgio Abbiati and
• Monica Dell’Acqua

Beilstein J. Org. Chem. 2015, 11, 1997–2006, doi:10.3762/bjoc.11.216

• results are summarized in Table 1. The reaction was ineffective under thermal conditions (Table 1, entry 1). As a consequence we tested simple Lewis acids as potential promoters for the transformation. Magnesium perchlorate, scandium and copper triflate and boron trifluoride failed to give the desired

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

Development of variously functionalized nitrile oxides

• Haruyasu Asahara,
• Keita Arikiyo and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2015, 11, 1241–1245, doi:10.3762/bjoc.11.138

• of the solvent, the residue was dissolved into diethyl ether (5 mL), washed with water (5 mL), and the aqueous layer was extracted with diethyl ether (2 × 5 mL). The combined organic layer was dried over magnesium sulfate, and concentrated, and the residue was subjected to column chromatography on

TTFs nonsymmetrically fused with alkylthiophenic moieties

• Rafaela A. L. Silva,
• Bruno J. C. Vieira,
• Marta M. Andrade,
• Isabel C. Santos,
• Sandra Rabaça,
• Dulce Belo and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 628–637, doi:10.3762/bjoc.11.71

• was poured into ice water, neutralized with sodium hydrogen carbonate and extracted with dichloromethane. After drying with magnesium sulfate, the solvent was evaporated. The crude product was purified by column chromatography using n-hexane/ethyl acetate (10:1) as eluent and further recrystallized

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• -addition of the carbonyl group is always a concern. In this case, the 1,2-addition product was not observed. The authors concluded that the 1,2-addition reaction did not occur because the magnesium salts that were present in the solution would be chelated strongly by the oxygen in the chiral auxiliary and

• the oxygen of the resulting enolate of the CA reaction. This chelation to the magnesium would retard the 1,2-addition reaction from occurring. Since the Mukaiyama publication, there have been many chiral auxiliaries studied in DCA reactions of α,β-unsaturated amides [35]. Figure 2 highlights a few of

• copper in CA reactions will preferentially form the 1,4-addition product [1]. Since then, copper has been the most commonly used metal in DCA and ECA reactions. In terms of the nucleophiles that are used, mainly alkyl organometallic reagents derived from zinc, aluminium, lithium and magnesium are used [1

Cathodic reductive coupling of methyl cinnamate on boron-doped diamond electrodes and synthesis of new neolignan-type products

• Taiki Kojima,
• Rika Obata,
• Tsuyoshi Saito,
• Yasuaki Einaga and
• Shigeru Nishiyama

Beilstein J. Org. Chem. 2015, 11, 200–203, doi:10.3762/bjoc.11.21

• magnesium (Mg), were examined as cathodes under the optimized electrolytic conditions (Table 1, entry 11). Hydrogen evolution at the electrode was recognized when Pt and Mg electrodes were used, and the educt 1a was recovered in high yield. The GC electrode provided the coupling product 2 (34%, racemate

Formation of nanoparticles by cooperative inclusion between (S)-camptothecin-modified dextrans and β-cyclodextrin polymers

• Thorbjørn Terndrup Nielsen,
• Catherine Amiel,
• Laurent Duroux,
• Kim Lambertsen Larsen,
• Lars Wagner Städe,
• Reinhard Wimmer and
• Véronique Wintgens

Beilstein J. Org. Chem. 2015, 11, 147–154, doi:10.3762/bjoc.11.14

• EDC (982 mg, 5.02 mmol) were added and the solution was stirred at rt overnight. TLC showed complete conversion of the CPT and the solution was washed with water (3 × 100 mL), brine (100 mL) and dried over magnesium sulfate. The solution was filtered, concentrated to approx. 10 mL in vacuo and

One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates

• Joshua P. Barham,
• Matthew P. John and
• John A. Murphy

Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316

• BrCCl3 and its byproduct CHCl3 [22] were responsible for poor organometallic reaction profiles. Generation of radical intermediates or carbenes upon reacting Grignard reagents or magnesium salts with BrCCl3 or CHCl3 are evidenced in the literature [38][39]. Initially, we took advantage of the

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• complete clearing of the oil. The aqueous phase was removed and the yellow oil was dissolved in a saturated aq NaHCO3 solution, the medium was acidified with 5% aq H2SO4 and heated. The dense yellow oil was extracted with ethyl acetate, dried over anhydrous magnesium sulfate, filtered and evaporated under

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• clear further in this review. An overview of different possible setups for obtaining carboxylic acids is given in Scheme 6. Electrocarboxylation reactions can either be conducted with a sacrificial anode, like magnesium or aluminum, or with an inert anode, like platinum or carbon. Most research has been

• done using a setup with a sacrificial magnesium or aluminum anode. The general mechanism of alkyne electrocarboxylation to a 1,4-dicarboxylated product is shown in Scheme 9. It is highly similar to the mechanism for electrocarboxylation of olefins. In these reactions a high selectivity for

• were conducted in a divided cell, giving only moderate yields [114][115]. A drastic increase in efficiency was obtained by employing sacrificial anodes [116], especially magnesium anodes [117][118]. The cathode material is again of great importance, with silver and platinum giving the highest

Autonomous assembly of synthetic oligonucleotides built from an expanded DNA alphabet. Total synthesis of a gene encoding kanamycin resistance

• Kristen K. Merritt,
• Kevin M. Bradley,
• Daniel Hutter,
• Mariko F. Matsuura,
• Diane J. Rowold and
• Steven A. Benner

Beilstein J. Org. Chem. 2014, 10, 2348–2360, doi:10.3762/bjoc.10.245

• nucleotide overlap with melting temperatures predicted to lie in a narrow range (44–56 °C; calculated without magnesium). OligArch also designed the sequences to have no-off target hybrids having a melting temperature greater than 25 °C, a full 20 °C below that predicted for the desired annealing pairs. Two

• magnesium; using the nearest neighbor formula from http://www.clinchem.org/content/45/12/2094.long; melting temperatures in 10 mM MgCl2 are expected to be ~10 °C higher) The S:B pair was assumed to contribute to duplex stability the same as the C:G pair. Enthalpy and entropy values for nucleotide pairs in

Molecular recognition of AT-DNA sequences by the induced CD pattern of dibenzotetraaza[14]annulene (DBTAA)–adenine derivatives

• Marijana Radić Stojković,
• Marko Škugor,
• Łukasz Dudek,
• Jarosław Grolik,
• Julita Eilmes and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2175–2185, doi:10.3762/bjoc.10.225

• , washed with water (2 × 100 mL), dried over anhydrous magnesium sulfate, concentrated to a small volume, and chromatographed on a column of silica gel with dichloromethane/methanol (20:0.5 to 20:1 v/v) as an eluent. The main orange fraction was collected and evaporated to dryness. A residue was dissolved

• was separated and washed thoroughly with water (5 × 30 mL), dried over anhydrous magnesium sulfate, concentrated to a small volume, and chromatographed on a column of silica gel with dichloromethane/methanol (10:0.6 v/v) as an eluent. The second fraction was collected from the two orange ones which

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• . The organic extracts were washed with water and dried over magnesium sulfate. The DCM solution was concentrated by rotary evaporation and precipitated in hexane to remove free TMS-β-CD. The yellow polymer sample was filtered. After drying the solid was purified by Soxhlet extraction with methanol for

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• corresponding to the photoproduct(s). At the end of the photolysis, the solution contained an orange-colored precipitate. The organic soluble components were extracted with ethyl acetate, and the organic extract was washed with water, dried over magnesium sulfate, and the solvent removed under reduced pressure

Influence of cyclodextrin on the UCST- and LCST-behavior of poly(2-methacrylamido-caprolactam)-co-(N,N-dimethylacrylamide)

• Alexander Burkhart and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1951–1958, doi:10.3762/bjoc.10.203

• mixture is washed with brine and water. The organic phase is dried over magnesium sulfate, filtered and the solvent is evaporated under reduced pressure. A colorless solid is obtained. Mp = 125 °C; Yield: 4.7 g (23.9 mmol, 61%); FTIR (diamond), ν (cm−1): 3252 (br. NH), 2923 (s, CH), 2857 (m, CH), 1650 (s

Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

• Maroš Bella,
• Bohumil Steiner,
• Vratislav Langer and
• Miroslav Koóš

Beilstein J. Org. Chem. 2014, 10, 1942–1950, doi:10.3762/bjoc.10.202

• unambiguously confirmed by single-crystal X-ray analysis. The formation of o-tolyl isomers 4 and 5 can be explained by the possible reaction sequence (path 1) depicted in Scheme 2. The first step involves an addition of the Grignard reagent to the saccharide aldehyde, producing a trienic magnesium alkoxide

• intermediate A (magnesium salt of 2-R-hydroxymethyl-1-methylene-1,2-dihydrobenzene, where R is the saccharide moiety) which, upon quenching with aqueous NH4Cl, affords (via an intermediate B) the corresponding o-tolyl isomer (a mixture of diastereomeric alcohols 4 and 5). A similar mechanism was proposed [24

• ][25] for the reaction of 1-naphthylmethylmagnesium chloride (10) with some aldehydes and ketones (Scheme 3). However, in this case, a trienic magnesium alkoxide intermediate E (magnesium salt of 2-hydroxymethyl-1-methylene-1,2-dihydronaphthalene, an analogue of intermediate A in Scheme 2, path 1

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

• magnesium chloride solution, 20 g/L agar only for plates) at 28 °C for 3 days. SM-agar plates were then inoculated with 300 µL of the preculture and cultivated for 6 days at 28 °C. Then the culture was analyzed by closed-loop stripping analysis at room temperature [7]. In this system, air is continuously

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 procedure by Fringuelli et al. [39] nerol (2) was treated with magnesium monoperoxyphthalate (MPPA) in the presence of NaOH to give 2,3-epoxynerol (6) in 77% yield together with 20% of reisolated starting material 2 (see Supporting Information File 1). According to a method by McMurry [24

• hindrance were selected. Terpene substrates (grey background) and their oxidised derivatives. a) Ac2O, pyridine, room temperature, 24 h; b) SeO2, t-BuOOH, CH2Cl2, 0 °C, 5 h; c) K2CO3, MeOH, room temperature, 2.5 h; d) MPPA, NaOH, H2O, room temperature, 5 h (MPPA = magnesium monoperoxyphthalate). a) SeO2, t

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• Abstract A new, efficient and mild method for the direct oxidation of selenides to selenones using magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) has been developed. Noteworthy this transformation proceeds at room temperature, employs a cheap and safety oxidant and has a broad functional group

• investigated the use of magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) as a new oxidant for the straightforward conversion of selenides 1 to selenones 2 under mild experimental conditions. Magnesium bis(monoperoxyphthalate) hexahydrate is a cheap commercially available, relatively stable and easy to use

• corresponding selenone in 68% yield. It is noteworthy that the reaction byproduct magnesium phthalate is water soluble and easy to separate during work-up; acidification of the water phase and extraction with dichloromethane allows to recover the pure phthalic acid in excellent yield. This protocol was then

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• derivative with limited stability, which was immediately converted into alcohol 4 by diastereoselective Felkin–Anh type Grignard addition with isopropyl magnesium chloride (50% yield over 2 steps from 3, dr > 95:5). However, we could not confirm that the use of diethyl ether as co-solvent in the Grignard

• acyclic D-serinal derivatives for the addition of nucleophiles to amino acid-derived aldehydes [33][34]. However, Zhu and co-workers have pointed out that Garner’s aldehyde surprisingly furnishes the syn diastereomer as the major product from its reaction with isopropyl magnesium chloride [32], thus

• formation of 8 in moderate to good yields (Table 1, entries 4–6). Finally, when 2,2-DiMP was used as solvent with catalytic amounts of CSA in the presence of magnesium sulfate, 8 could be isolated in a very good yield of 93% (Table 1, entry 7). After TBAF-mediated cleavage of the silyl ether, the resultant

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

A new building block for DNA network formation by self-assembly and polymerase chain reaction

• Holger Bußkamp,
• Sascha Keller,
• Marta Robotta,
• Malte Drescher and
• Andreas Marx

Beilstein J. Org. Chem. 2014, 10, 1037–1046, doi:10.3762/bjoc.10.104

• denaturation studies (cf. Figure 2). The self-complementary oligonucleotides (5 μM) were annealed in 10 mM triethylammonium acetate buffer at pH 7 in the presence of sodium chloride (150 mM), sodium chloride and magnesium chloride (150 mM and 100 mM, respectively) or in the absence of salts. The solutions were

• melting in all buffers tested (data not shown). In magnesium ion-containing buffer the CG 2-mer (ODN-sc-I) shows a higher melting temperature (37.6 °C) as the ODN-sc-II 4-mer (24.3 °C). The GC-rich 4-mer ODN-sc-III shows high melting temperatures even in the presence of only sodium chloride (58.0 °C) and

• an even higher melting temperature in the presence of additional magnesium (73.0 °C). The melting temperature in presence of sodium chloride and magnesium is even higher than the respective melting temperature of the 6-mer ODN-sc-IV (50.7 °C). All in all, one can conclude that the self-assembly of GC