Continuous flow nitration in miniaturized devices

• Amol A. Kulkarni

Beilstein J. Org. Chem. 2014, 10, 405–424, doi:10.3762/bjoc.10.38

Intermediates in monensin biosynthesis: A late step in biosynthesis of the polyether ionophore monensin is crucial for the integrity of cation binding

• Wolfgang Hüttel,
• Jonathan B. Spencer and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 361–368, doi:10.3762/bjoc.10.34

• mm−1, F(000) = 1532. LC–MS-analysis of purified monensin-related metabolites. Monensin B derivatives (peaks marked with B) were identified as minor components of the product mixture. The triple peak for dehydroxydemethylmonensin A (3) is due to an enrichment of disodium-species at the start and the

SF002-96-1, a new drimane sesquiterpene lactone from an Aspergillus species, inhibits survivin expression

• Silke Felix,
• Louis P. Sandjo,
• Till Opatz and
• Gerhard Erkel

Beilstein J. Org. Chem. 2013, 9, 2866–2876, doi:10.3762/bjoc.9.323

• immunoprecipitation (input) was subjected to quantitative real-time PCR using primers specific for Stat3 and p65 binding sites in the survivin promoter or control primers flanking the gapdh promoter. Values are expressed as fold enrichment of transcription factor binding relative to IgG as negative control. Data are

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• diastereoisomers of a versatile fluorinated C4 building block at high enantiomeric-enrichment. The (DHQ)2AQN and (DHQD)2AQN ligands described by Sharpless were the most effective. The development and optimisation of a new and facile method for the determination of ee is also described; 19F{1H} spectra recorded in

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• reactions run in toluene was the ternary adduct 12a,b in which one molecule each of β-nitrostyrene, diene, and toluene was incorporated. This material was isolated in 10% yield as an inseparable 70:30 mixture in which the p-isomer predominated. Some partial enrichment of the p-isomer was possible through

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

• investigated without any modification of the illustrated setup. Despite the advantage of an enrichment of the in-line sample concentration by the cryogenic CO2 setup, reactions can be studied in greater detail. Individual reaction steps can be slowed down by cooling only locally at different positions of a

Isotopically labeled sulfur compounds and synthetic selenium and tellurium analogues to study sulfur metabolism in marine bacteria

• Nelson L. Brock,
• Christian A. Citron,
• Claudia Zell,
• Martine Berger,
• Irene Wagner-Döbler,
• Jörn Petersen,
• Thorsten Brinkhoff,
• Meinhard Simon and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 942–950, doi:10.3762/bjoc.9.108

• or sulfate, sodium sulfate deficient half-strength marine broth agar medium was amended after autoclavation with 2.9 mmol/l Na234SSO3 (50% 34S-enrichment) or 5.7 mmol/l NaH34SO4 (25% 34S-enrichment). For the feeding experiments with [methyl-2H3]methionine, selenate, and selenite, half-strength marine

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• of the aldol product was observed. Subsequently, Bolm and co-workers also reported an enantio-enrichment of a scalemic aldol product 3b by iterative retro-aldol/aldol reactions of anti-aldol product in the presence of an achiral or racemic catalyst, i.e., pyrrolidine, by magnetically stirring a

• solution of the anti-aldol product (800 rpm) in DMSO, with ZrO2 beads as the grinding medium [32]. The enantioselectivity of the aldol product increases from an initial 70% ee to 92% ee after one day. Subsequently, after two and eleven days, a slow enantio-enrichment (95% ee and 96% ee, respectively) was

Automated three-component synthesis of a library of γ-lactams

• Erik Fenster,
• David Hill,
• Oliver Reiser and
• Jeffrey Aubé

Beilstein J. Org. Chem. 2012, 8, 1804–1813, doi:10.3762/bjoc.8.206

• with the modest enantiomeric enrichment in hand. Combination of three discrete steps into a single-pot process We next turned our attention to combining the initial Michael addition step with the remaining reductive amination/lactamization and epimerization steps. In the original procedure, the

Asymmetric one-pot sequential Friedel–Crafts-type alkylation and α-oxyamination catalyzed by a peptide and an enzyme

• Kengo Akagawa,
• Ryota Umezawa and
• Kazuaki Kudo

Beilstein J. Org. Chem. 2012, 8, 1333–1337, doi:10.3762/bjoc.8.152

• diastereomer was 96% (Table 1, entry 1). It is noteworthy that the ee of the major diastereomer was higher than that of each single reaction [33][37]. Such enantio-enrichment is generally caused in consecutive catalytic asymmetric reactions through the formation of diastereomeric pairs [17][41]. From the

Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119

• enrichment of the trans isomer (63%). The study of the photoisomerization process of 13 revealed that the configurational change of the azobenzene unit causes a sequence of molecular motions of the units connected to it. The ferrocene unit rapidly responds by turning, which in turn induces an opening motion

Carbamate-directed benzylic lithiation for the diastereo- and enantioselective synthesis of diaryl ether atropisomers

• Abigail Page and
• Jonathan Clayden

Beilstein J. Org. Chem. 2011, 7, 1327–1333, doi:10.3762/bjoc.7.156

• enantiomeric enrichment in the product 5 [22]. In this paper we report parallel studies on the attempted asymmetric synthesis of atropisomeric diaryl ethers in diastereomerically and/or enantiomerically enriched form by the directed deprotonation and electrophilic quench of benzylic positions ortho to a

Directed ortho,ortho'-dimetalation of hydrobenzoin: Rapid access to hydrobenzoin derivatives useful for asymmetric synthesis

• Inhee Cho,
• Labros Meimetis,
• Lee Belding,
• Michael J. Katz,
• Travis Dudding and
• Robert Britton

Beilstein J. Org. Chem. 2011, 7, 1315–1322, doi:10.3762/bjoc.7.154

• associated with their optical enrichment [6], and the necessary determination of optical purity for each derivative, all complicate the rapid preparation of congeneric libraries. To address these issues, we recently reported a new process for the direct functionalization of (R,R)-hydrobenzoin (3) [23

Synthesis of enantiomerically enriched (R)-¹³C-labelled 2-aminoisobutyric acid (Aib) by conformational memory in the alkylation of a derivative of L-alanine

• Stephen P. Fletcher,
• Jordi Solà,
• Dean Holt,
• Robert A. Brown and
• Jonathan Clayden

Beilstein J. Org. Chem. 2011, 7, 1304–1309, doi:10.3762/bjoc.7.152

• required a reliable source of 2-aminoisobutyric acid (Aib) 1 (Figure 1) bearing an isotopically labelled methyl group in enantiomerically enriched form, i.e., (R)- or (S)-1* or its derivatives. Specifically for our purposes, a high degree of enantiomeric enrichment was not necessary, since we were aiming

Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

• Paul W. Davies,
• Nicolas Martin and
• Neil Spencer

Beilstein J. Org. Chem. 2011, 7, 839–846, doi:10.3762/bjoc.7.96

• subjecting 11 to the conditions for skeletal rearrangement (Scheme 7), three enhanced resonances were seen in the 13C NMR spectra of the pyrrole products (Supporting Information File 1). One of the enhanced resonances was associated with the minor 2,5-disubstituted isomer 16 showing 13C enrichment at the

• enhancements were therefore assigned to the unexpected formation of two separate isotopomers of 17. 13C-enrichment at C-5 (117.7 ppm) corresponds to the isotopomer 17a anticipated from the proposed 1,2-aryl shift mechanism. Isotopomer 17b was identified by enrichment at the quaternary C-4 position (127.0 ppm

• conditions: Only a single isotopomer of the 2,4-disubstituted pyrrole 19 was formed with 13C-enrichment at the C-5 position, alongside the 2,5-disubstituted isomer 18 (Scheme 9). The observed inconsistency between the reactions of 11 and 14 was investigated using alkyl substituted alkynyl aziridine 15

Functionalized copolyimide membranes for the separation of gaseous and liquid mixtures

• Nadine Schmeling,
• Roman Konietzny,
• Daniel Sieffert,
• Patrick Rölling and
• Claudia Staudt

Beilstein J. Org. Chem. 2010, 6, 789–800, doi:10.3762/bjoc.6.86

• market currently has a steady growth of approximately 10–15% each year [3]. Membrane based separations of gaseous mixtures have been well established for natural gas treatments (removal of carbon dioxide), for hydrogen removal (e.g. in cracking processes) for oxygen enrichment from air (medical devices

• ) and for nitrogen enrichment from air (used as an inert atmosphere for oxygen sensitive compounds). Other areas with fast growing market relevance are vapor recovery systems [4], monomer recovery units, e.g. ethylene/nitrogen or propylene/nitrogen [5][6], the dehydration of organic solvents and the

RAFT polymers for protein recognition

• Alan F. Tominey,
• Julia Liese,
• Sun Wei,
• Klaus Kowski,
• Thomas Schrader and
• Arno Kraft

Beilstein J. Org. Chem. 2010, 6, No. 66, doi:10.3762/bjoc.6.66

• protein enrichment and purification, sensing and diagnostics applications, as well as therapeutic uses involving interference with critical protein–protein interactions. Multivalency represents the key to generate high-affinity materials for biomacromolecules with a sufficient number of binding sites for

Synthesis and properties of calix[4]arene telluropodant ethers as Ag⁺ selective sensors and Ag⁺, Hg²⁺ extractants

• Yang Lu,
• Yuanyuan Li,
• Song He,
• Yan Lu,
• Changying Liu,
• Xianshun Zeng and
• Langxing Chen

Beilstein J. Org. Chem. 2009, 5, No. 59, doi:10.3762/bjoc.5.59

• their potential receptor properties for cations, anions and neutral molecules, calixarenes have enjoyed widespread use in various areas of science and technology. One of their successful applications as sensors is in analytical chemistry. They are useful for separations, enrichment, and analyses of

Diastereoselective and enantioselective reduction of tetralin- 1,4-dione

• E. Peter Kündig and
• Alvaro Enriquez-Garcia

Beilstein J. Org. Chem. 2008, 4, No. 37, doi:10.3762/bjoc.4.37

• efficient highly diastereoselective one-step reduction of both carbonyl functions in 2 have not been realized, enrichment of one or the other diastereoisomer by choice of reducing agent is feasible and acceptable yields of pure diastereoisomers can be obtained. Enantioselective bis-reduction of 2 Asymmetric