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

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

• occurs before the TS in both cases. In contrast to these concerted reaction mechanisms, the decarboxylation of the zwitterions 5 and 6 appears to have a very low or near to zero activation barrier and is likely to dominate the reaction pattern. We therefore looked more closely to the products of the

Diradical reaction mechanisms in [3 + 2]-cycloadditions of hetaryl thioketones with alkyl- or trimethylsilyl-substituted diazomethanes

• Grzegorz Mlostoń,
• Paulina Pipiak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2016, 12, 716–724, doi:10.3762/bjoc.12.71

• . Remarkably, in no single case, the ‘head-to-head dimerization’ of aryl/hetaryl and dihetaryl substituted thiocarbonyl ylides was observed. Keywords: [3 + 2]-cycloadditions; diazoalkanes; diradicals; 1,3-dithiolanes; reaction mechanisms; thioketones; Introduction Cycloaddition reactions belong to the most

Dynamic behavior of rearranging carbocations – implications for terpene biosynthesis

• Stephanie R. Hare and
• Dean J. Tantillo

Beilstein J. Org. Chem. 2016, 12, 377–390, doi:10.3762/bjoc.12.41

• these aspects of reaction mechanisms. Unique potential energy surface topologies associated with these rearrangements have been discovered in recent years that are not only of fundamental interest, but also provide insight into the way Nature manipulates chemical space to accomplish specific chemical

• available today), this study paved the way for future dynamics studies and correctly predicted that “similar findings will arise for many other reactions … and interpretation of reaction mechanisms ought to consider the effects of dynamics explicitly” [46]. In light of more recent studies (e.g., see below

• product following an ambimodal TSS due to dynamic matching. Right: an intermediate that is rapidly passed through or bypassed as a result of dynamic matching. The tetramethylbromonium ion system [14]. The reaction mechanisms of interest in the PES and dynamics studies of Dupuis and co-workers (R = CH3

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• milling conditions favours SN2 reactions; however it is also true that a solventless environment does not necessarily mean that there is a lack of solution in a liquid phase. Some reaction mixture components can often be liquid, while solvent effects or mixed SN2 and SN1-type reaction mechanisms cannot be

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• wonderful mistake that led to my learning an enormous amount of exciting synthetic chemistry. Indeed, in going to Columbia University for graduate school I had every intention of working for Professor Gilbert Stork or W. Clark Still. But Professor Ronald Breslow’s enzyme reaction mechanisms course, my first

Copper-catalysed asymmetric allylic alkylation of alkylzirconocenes to racemic 3,6-dihydro-2H-pyrans

• Emeline Rideau and
• Stephen P. Fletcher

Beilstein J. Org. Chem. 2015, 11, 2435–2443, doi:10.3762/bjoc.11.264

• assistance of a design of experiments statistical approach (83% ee, 12% yield). 1H NMR spectroscopy was used to gain insight into the reaction mechanisms. Keywords: allylic alkylation; asymmetric catalysis; copper; design of experiments; dynamic kinetic asymmetric transformation; heterocycles; Schwartz

Computational study of productive and non-productive cycles in fluoroalkene metathesis

• Markéta Rybáčková,
• Jan Hošek,
• Ondřej Šimůnek,
• Viola Kolaříková and
• Jaroslav Kvíčala

Beilstein J. Org. Chem. 2015, 11, 2150–2157, doi:10.3762/bjoc.11.232

• valuable in the study of reaction mechanisms. In particular, the use of time-efficient DFT methods for the theoretical study of alkene metathesis has been extensively reviewed [9][10][11] and computational results have been found to agree well with recent experimental mechanistic studies based on easily

A convenient four-component one-pot strategy toward the synthesis of pyrazolo[3,4-d]pyrimidines

• Mingxing Liu,
• Jiarong Li,
• Hongxin Chai,
• Kai Zhang,
• Deli Yang,
• Qi Zhang and
• Daxin Shi

Beilstein J. Org. Chem. 2015, 11, 2125–2131, doi:10.3762/bjoc.11.229

• results in hand, two possible reaction mechanisms were proposed and shown in Scheme 3. 5-Aminopyrazole-4-carbonitrile 6 was obtained from the reaction of hydrazine 1 and methylenemalononitrile 2 through nucleophilic addition, cyclization and aromatization. The nucleophilic attack of the amino group of 6

• pyrazolo[3,4-d]pyrimidines. Synthesis of 5a from different intermediates. Possible reaction mechanisms for the formation of pyrazolo[3,4-d]pyrimidiine. Optimization of the reaction conditionsa. Supporting Information Supporting Information File 544: Experimental section and copies of 1H and 13C NMR

Copper-catalyzed aerobic radical C–C bond cleavage of N–H ketimines

• Ya Lin Tnay,
• Gim Yean Ang and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2015, 11, 1933–1943, doi:10.3762/bjoc.11.209

• . Copper-catalyzed aerobic C–C bond cleavage reactions of N–H ketimines. Proposed reaction mechanisms for the formation of 3a, 4a and 5a, and the reaction of hydroperoxide 6. Formation of bromoketone 6e. Electrophilic cyanation of Grignard reagents with pivalonitrile (1f). Electrophilic cyanation with

A novel and widespread class of ketosynthase is responsible for the head-to-head condensation of two acyl moieties in bacterial pyrone biosynthesis

• Darko Kresovic,
• Florence Schempp,
• Zakaria Cheikh-Ali and
• Helge B. Bode

Beilstein J. Org. Chem. 2015, 11, 1412–1417, doi:10.3762/bjoc.11.152

• KS is distinct from PpyS but also its evolutionary relationship, even if they produce a similar class of compound. Thus, the phylogenetic analysis is also useful to distinguish between reaction mechanisms of different KS. In order to prove that the identified PpyS homologues are indeed involved in

Novel carbocationic rearrangements of 1-styrylpropargyl alcohols

• Christine Basmadjian,
• Fan Zhang and
• Laurent Désaubry

Beilstein J. Org. Chem. 2015, 11, 1017–1022, doi:10.3762/bjoc.11.114

• reaction mechanisms, we explored different reaction conditions starting from alcohol 21 (Table 2). 1,2-Dichloroethane and dichloromethane (entries 1 and 2, Table 2) gave better yields (27–31% for 22 and 10–16% for 23) compared to THF (entry 3, Table 2). In an effort to understand the role of Re2O7, the

Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions – synthesis of halohydrins and epoxides

• Akihiro Shimizu,
• Ryutaro Hayashi,
• Yosuke Ashikari,
• Toshiki Nokami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2015, 11, 242–248, doi:10.3762/bjoc.11.27

• halohydrins and epoxides from alkenes. The method is also useful for synthesizing 18O-labeled epoxides. Synthesis of halohydrins and epoxides through β-haloalkoxysulfonium ions generated by the reaction of alkenes with DMSO-stabilized halogen cations. Proposed reaction mechanisms for the syntheses of

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• for an extremely broad variety of substances [2], but has also been recognized as a valuable tool for studying reaction mechanisms by transferring species of a reacting solution directly into the gas phase of a mass spectrometer [3][4][5][6][7]. The technique allows glimpses into the reacting solution

Theoretical studies on the intramolecular cyclization of 2,4,6-t-Bu₃C₆H₂P=C: and effects of conjugation between the P=C and aromatic moieties

• Masaaki Yoshifuji and
• Shigekazu Ito

Beilstein J. Org. Chem. 2014, 10, 1032–1036, doi:10.3762/bjoc.10.103

• phosphanylidenecarbenoid (Scheme 1) [11][12][13]. The phosphorus version of FBW rearrangement showed considerable stereospecificity in affording phosphaalkyne, which could be explicable by plausible reaction mechanisms including formation of the phosphavinyl anion intermediate without generation of phosphanylidenecarbene

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• experimentally not (easily) available. However, it is likely that their potential is greater than 0 V in many cases which makes the radical species III a sufficiently strong reductant for arenediazonium salts of type I. After all, the unambiguous determination of the underlying reaction mechanisms is not

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• for the NVK double bond in the course of the polymerization. (A) Photopolymerization profile of TMPTA; initiating systems: (1) Ir(piq)2(tmd)/MDEA (1%/2%) and (2) Ir(piq)2(tmd)/MDEA/R-Br (1%/2%/3%); laser diode at 532 nm; in laminate. Examples of photoinitiating systems. Reaction mechanisms for the

• three-component system PIC/eA/E-Z. Reaction mechanisms for the two-component system PIC/eA. Reaction mechanisms for the system PIC/eA/add. Reaction mechanisms for the system PIC/eD/B-Y. Reaction mechanisms for the system Ru(bpy)32+/Ph2I+/R3SiH. Reaction mechanisms for the Ru(ligand)32+/Ph3S+/R3SiH

• system. Reaction mechanisms for the Ru(ligand)32+/Ph2I+/NVK system upon visible lights. Reaction mechanisms for the violanthrone/Ph2I+/TTMSS (R3SiH) system upon red lights. Reaction mechanisms for the Tr-AD/R-Br/MDEA system upon visible lights. The photoredox catalysis for controlled polymerization

Direct and indirect single electron transfer (SET)-photochemical approaches for the preparation of novel phthalimide and naphthalimide-based lariat-type crown ethers

• Dae Won Cho,
• Patrick S. Mariano and
• Ung Chan Yoon

Beilstein J. Org. Chem. 2014, 10, 514–527, doi:10.3762/bjoc.10.47

• ., phthalimides and naphthalimides), have been developed for the synthesis of novel lariat-type crown ethers. Parallel investigations on the reaction mechanisms have provided a useful guideline for predicting the chemo- and regioselectivties and efficiencies of these excited state reactions. These observations

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• area of cycloaddition reactions, which are of particular interest due to their potential for the rapid construction of optically active cyclic products. In this article we will summarize some of the most remarkable examples, emphasizing reaction mechanisms and key intermediates involved in the

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• well as products of these reactions are potentially capable of promoting further degradation processes in polyesters under environmental conditions. Keywords: environmental oxidants; free radicals; nitrate radicals; polyester degradation; product studies; reaction mechanisms; Introduction Polymers

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

• be potential intermediates in the Appel reaction [58][59] and consequently we also wished to investigate the interplay between the two reaction mechanisms. Results and Discussion Formation of the triphenylphosphine monolith The triphenylphosphine monoliths for the Ramirez reactions were formed using

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

• André S. Kelch,
• Peter G. Jones,
• Ina Dix and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195

• acetylenedicarboxylate (22) with dimethyl malonate (23) under the catalytic influence of pyridinium acetate, the fully substituted cycloheptadienes 24 and 25 (Scheme 5) were produced; both authors also proposed reaction mechanisms for this complex transformation that can be considered as reasonable even today; for the

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

• . Moreover, recent experimental and theoretical reports are analyzed, which suggest the involvement of such intermediates in reaction mechanisms, particularly C–H bond-activation processes. Keywords: C–H bond activation; intermediate; platinum(II); reactive intermediates; three-coordinate; T-shaped; Review

• large number of reaction mechanisms. A review concerning dissociative pathways in Pt(II) complexes was published in 1990 [113]. Due to both the low electron count and the presence of a vacant site in the coordination sphere, T-shaped Pt(II) species are suitable intermediates in ligand-exchange and bond

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

• 1,5-H radical shift. Aliphatic C–H oxidation with hydroperoxides. Proposed reaction mechanisms for the formation of 2a, 3a, and 4a. Proposed reaction mechanisms for the formation of 5 and 6. The reaction of secondary hydroperoxide 1o. 1,4-Dioxygenation of alkanes. Aerobic 1,4-dioxygenation of alkanes

Gold-catalyzed oxycyclization of allenic carbamates: expeditious synthesis of 1,3-oxazin-2-ones

• Benito Alcaide,
• Pedro Almendros,
• M. Teresa Quirós and
• Israel Fernández

Beilstein J. Org. Chem. 2013, 9, 818–826, doi:10.3762/bjoc.9.93

• gold-catalyzed synthetic routes to 1,3-oxazinan-2-ones (kinetically controlled products) and 1,3-oxazin-2-one derivatives (thermodynamically favored) from easily accessible allenic carbamates has been carried out. Keywords: allenes; computational chemistry; gold; gold catalysis; heterocycles; reaction

• mechanisms; Introduction The search for new synthetic routes to 1,3-oxazin-2-one derivatives [1] is of interest because of the biological activity of these molecules [2][3][4][5][6][7]. Carretero and colleagues have published the Au(I)-catalyzed cyclization of N-Boc-3-butyn-1-amines to afford six-membered 2