One-pot synthesis of block-copolyrotaxanes through controlled rotaxa-polymerization

• Jessica Hilschmann,
• Gerhard Wenz and
• Gergely Kali

Beilstein J. Org. Chem. 2017, 13, 1310–1315, doi:10.3762/bjoc.13.127

• Jessica Hilschmann Gerhard Wenz Gergely Kali Organic Macromolecular Chemistry, Saarland University, Campus C4.2, 66123 Saarbrücken, Germany 10.3762/bjoc.13.127 Abstract The aqueous reversible addition fragmentation chain-transfer (RAFT) copolymerization of isoprene and bulky comonomers, an

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• , the sulfonamide group was reduced to a sulfinamide in the course of the reaction, and one of the former alkynyl carbons was oxidised to a ketone. The presence of the sulfinamide can be deduced from the fragmentation pattern in the mass spectrum where the loss of SO can be seen which is further

Towards open-ended evolution in self-replicating molecular systems

• Herman Duim and
• Sijbren Otto

Beilstein J. Org. Chem. 2017, 13, 1189–1203, doi:10.3762/bjoc.13.118

• of the fibers and it is therefore not surprising that the reaction rate is strongly dependent on the amount of fibers present in the mixture. As soon as a fiber reaches a critical length it can fragment when mechanically agitated. When fragmentation occurs, the number of available fiber ends is

Glyco-gold nanoparticles: synthesis and applications

• Federica Compostella,
• Olimpia Pitirollo,
• Alessandro Silvestri and
• Laura Polito

Beilstein J. Org. Chem. 2017, 13, 1008–1021, doi:10.3762/bjoc.13.100

• [45][56][57][58]. Prosperi and co-workers coated dodecanthiol AuNPs with manno-calixarenes exploiting hydrophobic interactions, obtaining an efficient targeting against cancer cells [56]. Similarly, a reversible addition−fragmentation chain transfer (RAFT) polymerization approach has been exploited

Cyclodextrins tethered with oligolactides – green synthesis and structural assessment

• Cristian Peptu,
• Mihaela Balan-Porcarasu,
• Alena Šišková,
• Ľudovít Škultéty and
• Jaroslav Mosnáček

Beilstein J. Org. Chem. 2017, 13, 779–792, doi:10.3762/bjoc.13.77

• spectroscopy. Liquid chromatography and tandem MS fragmentation studies [21][22][23] are also important additions in deeper structural characterization of CD-oligoester conjugates. The L-LA was reacted with α-, β- and γ-CD (Scheme 1) in bulk at 110 °C in order to ensure a good dispersion of reactants. The

Solid-phase enrichment and analysis of electrophilic natural products

• Frank Wesche,
• Yue He and
• Helge B. Bode

Beilstein J. Org. Chem. 2017, 13, 405–409, doi:10.3762/bjoc.13.43

• product could be directly detected in the base-peak chromatogram (BPC) showing the characteristic fragmentation pattern of the CARR adducts (Supporting Information File 1, Figure S3) [15]. Additionally, the detection limit of the model epoxide was investigated in a complex environment. For this, defined

• was incubated with 2, the disulfide bond was cleaved and the filtrate subsequently analyzed by HPLC–MS. To our surprise, the BPC showed one distinct peak at 8.1 min with a characteristic MS2 fragmentation pattern of a derivatized azide and a mass of m/z 567.2 [M + H]+. This mass corresponds to the

• species. Upon a detailed look at the chromatograms, different masses with the characteristic fragmentation pattern of derivatized azides could be found (Table 1 and Supporting Information File 1, Figures S7–S9). The molecular formula obtained from HRMS data indicates that three glidobactin derivatives

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• case the two-step protocol is followed by a lactamization and the one-pot reduction of ester and lactam groups of 18. The authors proposed a reductive anionic chain mechanism described in Scheme 10. The exposure of 14a to BH3 generates a borane–amine complex 20 whose fragmentation could be promoted by

• nitrile carbon to form the nitrogen centered radical 77. β-Fragmentation leads to NHC-boryl nitrile 74 and a carbon centered radical. A hydrogen atom transfer reaction between the electrophilic α-cyano radical and the nucleophile NHC-borane achieves the chain propagation (Scheme 24). The isolation of the

Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9

• and reversible addition fragmentation chain transfer (RAFT) polymerisation, amongst others [21], has been studied extensively by extrusion to produce, for example, branched polypropylene, polyethylene and polylactide polymers. The process involves the production of a free radical at the end of an

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• the Supporting Information File 1 for details). This is most probably a triethylammonium salt resulting from the use of triethylamine as a base during the preparation of the material. The ESI-MSn fragmentation pathway of 3 is shown in Figure 3 and starts with cleavage of the amide, followed by loss of

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

• Markus Menke,
• Pardha Saradhi Peram,
• Iris Starnberger,
• Walter Hödl,
• Gregory F.M. Jongsma,
• David C. Blackburn,
• Mark-Oliver Rödel,
• Miguel Vences and
• Stefan Schulz

Beilstein J. Org. Chem. 2016, 12, 2731–2738, doi:10.3762/bjoc.12.269

• basis of its EI mass spectrum. The occurrence of characteristic ions can be explained by the fragmentation pathway proposed in the article. In contrast, the localization of a double bond in many aliphatic open-chain compounds like alkenes, alcohols or acetates, important structural classes of pheromones

• present in 1 is shifted to m/z 182 in 2. These ions can be used to assign the location of the double bond in the macrocyclic ring. A possible fragmentation pathway leading to these ions is shown in Figure 5. One can speculate that after ionization of the double bond in 1 an allylic cleavage occurs

• formation along pathway b can be explained by homoallylic cleavage of 18 into 21 and further fragmentation into 22. The formation of the ions of this series is obviously determined by the position of the double bond in the chain. Therefore, ion m/z 182 of 2 arises by the same mechanism, indicating the

Synthesis of polyhydroxylated decalins via two consecutive one-pot reactions: 1,4-addition/aldol reaction followed by RCM/syn-dihydroxylation

• Michał Malik and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2016, 12, 2602–2608, doi:10.3762/bjoc.12.255

• -decalins and trans-hydrindanes (Scheme 1) [22][23][24][25]. It relies on the use of sugar-derived allyltin (such as 5) followed by ZnCl2-induced fragmentation into dienoaldehyde 6, subsequent Horner–Wadsworth–Emmons olefination, and intramolecular Diels–Alder reaction. In this paper, we explore the

• initiated from known iododerivatives 13 and 14, prepared from suitably protected carbohydrates (Scheme 3) [45][46][47]. Each of these compounds was subjected to the zinc-mediated fragmentation, followed by the Jones oxidation. The resulting acid (not purified) was transformed into a Weinreb amide. As a

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• recognition site is introduced to a reversible addition–fragmentation chain transfer (RAFT) polymerization system [65][66][67][68][69]. We have synthesized a chain transfer agent (CTA) bearing the CD moiety (CD-CTA) and have investigated this agent’s polymerization behavior. The polymerization rate constant

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

• the corresponding numbers are three, six, and one, where the number of each type of fragmentation is reduced by half. In general, rings that contain internal planes of symmetry have significantly fewer possible ring fragmentation patterns for a given partition type. This observation will figure

• byproduct of that route is methane, which is produced in the fragmentation of acetone [140]. It should be emphasized that the given conjectured routes are a subset of a full spectrum of possible solutions to the problem of making bond connections between nucleophilic and electrophilic centres in the

Methylenelactide: vinyl polymerization and spatial reactivity effects

• Judita Britner and
• Helmut Ritter

Beilstein J. Org. Chem. 2016, 12, 2378–2389, doi:10.3762/bjoc.12.232

• as methyl methacrylate were determined. To predict the copolymerization behavior with other classes of monomers, Q and e values were calculated. Further, reversible addition fragmentation chain transfer (RAFT)-controlled homopolymerization of methylenelactide and copolymerization with N,N

• -dimethylacrylamide was performed at 70 °C in 1,4-dioxane using AIBN as initiator and 2-(((ethylthio)carbonothioyl)thio)-2-methylpropanoic acid as a transfer agent. Keywords: copolymerization; kinetic study of the radical homopolymerization; push–pull monomer; reversible addition fragmentation chain transfer (RAFT

• -Michael additions on MLA were reported [11][12]. In this paper, we wish to present a kinetic study of free radical and controlled/living radical polymerization of MLA. The latter reactions were conducted via a reversible addition fragmentation chain transfer (RAFT) mechanism. We also investigated the

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines

• David R. Chisholm,
• Garr-Layy Zhou,
• Ehmke Pohl,
• Roy Valentine and
• Andrew Whiting

Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174

• addition of DIBAL on the product distribution. Increased NMR yields of DHQ 22 relative to THQ 21 were recorded (as shown in Table 1), as the temperature of the 20a solution was increased prior to DIBAL addition. This trend indicates that 22 may be formed from in situ fragmentation of the intermediate DIBAL

• reaction was conducted with a variety of quinolin-2-ones bearing differing alkyl substituents in order to ascertain whether steric effects promote collapse of the intermediate aluminium complex via fragmentation/elimination, and to assess the generality of this approach. Table 2 highlights the effect of

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• oxidative fragmentation at the bridgehead position of adamantanes 157a,b. The reaction employed the trifluoroperacetic acid (TFPAA)/trifluoroacetic acid (TFAA) system and afforded compounds 158a,b in high yields (Scheme 46) [300]. This method for the insertion of an oxygen atom was applied to the oxidation

• involves the formation of solvolytically generated cyclobutyl hydroperoxides 177 followed by the rearrangement of the latter into oxa-bridged, hydroperoxyhemiketals 176 (Scheme 53). The fragmentation of hydroperoxy acetals 178a–e in the presence of Ca(OCl)2 or t-BuOCl as the catalysts in CH3CN generating

• esters 179a–e proceeds through the Hock-like rearrangement mechanism (Table 12) [322]. The fragmentation of hydroperoxy acetals 178 to esters 179 involves the formation and heterolytic fragmentation of intermediate secondary chloroperoxides 180. The possible mechanism of the process is presented in

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• ionization and the peak of the molecular ion, the base peak and characteristic fragmentation peaks with their relative intensities are reported. Syntheses 3,3'-(Ethane-1,2-diyl)bis(4,5-dimethylthiazolium) dibromide (1a) A Schlenk flask was charged with 3.00 equiv 4,5-dimethylthiazole (1.00 g, 8.84 mmol) and

The EIMS fragmentation mechanisms of the sesquiterpenes corvol ethers A and B, epi-cubebol and isodauc-8-en-11-ol

• Patrick Rabe and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2016, 12, 1380–1394, doi:10.3762/bjoc.12.132

• EIMS fragmentation mechanisms of the two sesquiterpene ethers corvol ethers A and B, and the sesquiterpene alcohols epi-cubebol and isodauc-8-en-11-ol. Keywords: bacteria; isotopic labelling; mass spectrometry; reaction mechanisms; terpenes; Introduction Gas chromatography coupled to electron impact

• difficult. The profound knowledge about EIMS fragmentation reactions can be used to identify certain structural motifs, e.g., the mass spectra of acyclic carbonyl compounds are often dominated by fragment ions formed via McLafferty rearrangement [4], while cyclohexene derivatives often show major fragment

• , Ryhage and Stenhagen presented detailed studies on the EI mass spectra of deuterated and methyl-branched fatty acid methyl esters that revealed their fragmentation mechanisms [7][8]. Based on this work, we have recently identified various volatile fatty acid methyl esters (FAMEs) in headspace extracts of

Cyclisation mechanisms in the biosynthesis of ribosomally synthesised and post-translationally modified peptides

• Andrew W. Truman

Beilstein J. Org. Chem. 2016, 12, 1250–1268, doi:10.3762/bjoc.12.120

• -trivial due to the variety of unusual post-translational modifications that could take place. This means that product masses and fragmentation patterns are very difficult to predict, especially when peptides are cyclised [161]. Despite these issues, significant progress has been made to develop methods to

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• major fragmentation pathway is due to the loss of 64 Da (SO2) leading to an ion at an even value (m/z 374). The sequential loss of sulfur dioxide plus ammonia gives a fragment ion with m/z 357, indicating an even number of nitrogen atoms. Further loss of a camphor moiety (C10H15NSO2) displays an ion at

• m/z 227 supporting a species having an even number of nitrogen atoms (see Supporting Information File 1, Figure S7 showing a scheme with the fragmentation mechanism of 2). The formulation of 2 was corroborated by accurate mass measurements using QqTOF-MS which led to the following results (M

• . Supporting Information Supporting Information File 81: Experimental spectra for compound 2: FTIR, NMR (1H, 13C, DEPT, HMBC, HSQC, NOESY), ESIMS and the proposed fragmentation mechanism for 2 and 12. Supporting Information File 82: Calculations of the NMR chemical shifts for the assignment of the configuration

Tandem processes promoted by a hydrogen shift in 6-arylfulvenes bearing acetalic units at ortho position: a combined experimental and computational study

• Mateo Alajarin,
• Marta Marin-Luna,
• Pilar Sanchez-Andrada and
• Angel Vidal

Beilstein J. Org. Chem. 2016, 12, 260–270, doi:10.3762/bjoc.12.28

• several mechanistic paths are conceivable, each one involving additional H shifts and a fragmentation step, the opening of the dioxolane ring by a formal β-elimination reaction. A number of additional mechanistic alternatives arise by considering that the experimentally observed transformations of 3 are

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• out to be a three-year research experience. My initial goal was to identify six isomeric fragmentation products that were first observed by former student Dave Thomas (Figure 1). Once identified, I was tasked with elucidating the mechanism(s) that led to those products. What drew me into the lab was

Thermal and oxidative stability of Atlantic salmon oil (Salmo salar L.) and complexation with β-cyclodextrin

• Daniel I. Hădărugă,
• Mustafa Ünlüsayin,
• Alexandra T. Gruia,
• Cristina Birău (Mitroi),
• Gerlinde Rusu and
• Nicoleta G. Hădărugă

Beilstein J. Org. Chem. 2016, 12, 179–191, doi:10.3762/bjoc.12.20

• intermediates resulting from the oxidation of FAs are monohydroperoxides, hydroperoxy-epidioxides, as well as peroxy-, alkoxy-, and alkyl radicals [16]. Further thermal degradation or fragmentation of these intermediates leads to odor-active carbonyl compounds such as aldehydes, ketones, alcohols and esters

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• reactive in CM [35]. In the case of metathetic fragmentation of β-carotene, the use of 9 instead of 1 or 2 improved the regioselectivity. The product of the central C15–C15’ double bond scission was formed preferably. The activity of 9 was comparable to that of 1, albeit lower than 2 (Scheme 4). Regio- and

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• synthesis of these targets presently accessible through controlled and living polymerization techniques including controlled radical polymerizations (CRP) such as atom transfer radical polymerization (ATRP), nitroxide-mediated polymerization (NMP) and reversible addition–fragmentation chain transfer (RAFT