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

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

• . Finally, comparison of the reaction mechanisms involving hexaazamacrocyclic bsH2m and H3m ligands indicates that the energy barriers present in the H3m reaction mechanism are somewhat lower than those found in the more rigid bsH2m ligand. Stationary points located along the reaction path of the aromatic

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

• over the years. Our research is curiosity driven, guided by a search for novelty and a thirst for understanding reaction mechanisms. Constructing complex molecular architectures is only incidental to our work, mostly a consequence of our exploration of the scope and limitations of our methods. The

Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

• Martin Goez,
• Isabell Frisch and
• Ingo Sartorius

Beilstein J. Org. Chem. 2013, 9, 437–446, doi:10.3762/bjoc.9.46

• observed [8][9]. One of the most versatile methods to elucidate complex reaction mechanisms that occur via paramagnetic intermediates is provided by measurements of chemically induced dynamic nuclear polarization (CIDNP) [10][11][12][13][14][15]. CIDNP arises from a spin-sorting process in radical pairs

• spectroscopy attaches labels (the polarizations) at the stage of the intermediates and observes them in the products, thus highlighting the interconnections of species along the reaction coordinate. The present study thus again demonstrates the power of CIDNP to provide detailed insights into complex reaction

• mechanisms. Experimental TIPA was synthesized and purified according to a literature procedure [47]; DABCO and all the sensitizers were commercially obtained and purified by double sublimation. The purchased solvent acetonitrile-d3 was carefully dried to a water content of less than 5 × 10−4 M in a specially

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• phenylmagnesium reagent provided 3i whereas the reaction with a vinylmagnesium reagent gave 3j. The reaction mechanisms are shown in Scheme 25. They proposed that the carbon–carbon bond cleavage happened prior to the carbometalation reactions, which is different from other ring-opening reactions of cyclopropenes

A chemist and biologist talk to each other about caged neurotransmitters

• Graham C.R. Ellis-Davies

Beilstein J. Org. Chem. 2013, 9, 64–73, doi:10.3762/bjoc.9.8

• practical purposes we make stock solutions for freezing in aliquots, and only thaw for use at the desired time. Chemist: Since 1980, the rate of release of the caged compound has been the subject of study by those who develop caged compounds [3]. Since the reaction mechanisms are quite complex, these

• rate of release of product is the key property [3][62][63]. In fact this is one reason why chemists study reaction mechanisms, as there can be several intermediates along the reaction pathway, leading to transmitter release [73]. Unfortunately, there is no easy way to detect glutamate optically, so the

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

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

Discovery of practical production processes for arylsulfur pentafluorides and their higher homologues, bis- and tris(sulfur pentafluorides): Beginning of a new era of “super-trifluoromethyl” arene chemistry and its industry

• Teruo Umemoto,
• Lloyd M. Garrick and
• Norimichi Saito

Beilstein J. Org. Chem. 2012, 8, 461–471, doi:10.3762/bjoc.8.53

• these new reactions are revealed and reaction mechanisms are discussed. As the method offers considerable improvement over previous methods in cost, yield, practicality, applicability, and large-scale production, the new processes described here can be employed as the first practical methods for the

Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

• Vadim A. Soloshonok and
• Donna J. Nelson

Beilstein J. Org. Chem. 2011, 7, 744–758, doi:10.3762/bjoc.7.85

• demonstrated that such different data point groupings reflect different steric and electronic characteristics of the rate-determining transition states, intermediates, or products. These different patterns have corresponded to different reaction mechanisms [72][73][74][75][76][77][78]. Thus, the different

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• yields up to 94% of the para photocycloaddition product, while other substituents gave yields of up to 44% of the benzoxepine compound. Pericyclic reaction mechanisms for these two photocycloadditions have been proposed, but no hard evidence has so far been obtained. The mechanism of this unprecedented

• step. We have discussed the diverse selectivities of the reaction, mechanisms as well as further modifications, and some of the most recent applications in total synthesis. Thus, while meta photocycloadditions have been exploited for over thirty years, ortho and, in particular, para photocycloadditions

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• abstract hydride from another molecule that itself forms a stable cation (Scheme 5). In order to make the above mechanistic speculations more than simple “electron pushing”, we decided to apply the following computational methods. Reaction mechanisms by computational methods The gas phase global minima of