Emission and biosynthesis of volatile terpenoids from the plasmodial slime mold Physarum polycephalum

• Xinlu Chen,
• Tobias G. Köllner,
• Wangdan Xiong,
• Guo Wei and
• Feng Chen

Beilstein J. Org. Chem. 2019, 15, 2872–2880, doi:10.3762/bjoc.15.281

• similarities occurred between PpolyTPS1 and PpolyTPS4 (72%) and between PpolyTPS2 and PpolyTPS3 (64%). PpolyTPS1/4 and PpolyTPS2/3, however, showed only ≈30% sequence similarity to each other. Terpene synthases can be classified into class I and class II, based on the reaction mechanisms they catalyze. These

Acid-catalyzed rearrangements in arenes: interconversions in the quaterphenyl series

• Sarah L. Skraba-Joiner,
• Carter J. Holt and
• Richard P. Johnson

Beilstein J. Org. Chem. 2019, 15, 2655–2663, doi:10.3762/bjoc.15.258

• displays such a complex and fascinating collection of molecular rearrangements. Building on a long history, new synthetic applications [1][2] and explanations of carbocation reaction mechanisms [3][4][5][6] continue to be discovered. Chemistry in superacid solutions has played a major role in this field [7

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• the thermal back reaction after 313-nm light irradiation to 1o–3o in MeCN at 28 °C. Concentration of compounds are the same as in Figure 1. (a) 1c. (b) 2c. (c) 3c. Reaction mechanisms of Huisgen cyclization catalyzed by Cu(I) and Ru(I). Synthesis and photochromism of bisthiazolyltriazoles. Wavelengths

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• reaction mechanisms for these syntheses have not been reported. Therefore, we carried out several control experiments to clarify the reaction mechanism (Scheme 2). However, the reaction of 1-phenylbenzimidazole (11) without bromine at the phenyl group with diphenyl diselenide (12a) did not afford the

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• [1][2][11][12]. Moreover, the designed macrocycles are useful molecular tools in the investigation of supramolecular catalysis and reaction mechanisms [1][2][13][14][15][16]. Heteracalixaromatics or heteroatom-bridged calix(het)arenes [17][18][19][20][21] are synthetic macrocycles composed of

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• -arylmethyl-substituted benzimidazoles, in yields up to 90%. The reaction intermediates, protonated species derived from starting benzimidazoles in TfOH, were thoroughly studied by means of NMR and DFT calculations and plausible reaction mechanisms are discussed. Keywords: benzimidazoles; cations; Friedel

• ). Summarizing all data obtained by DFT calculations (Table 1) and NMR studies (Table 2) of intermediate cations generated from benzimidazoles 1–8 in TfOH, and their reactions with arenes (Tables 3–5, Scheme 1, and Scheme 2), the following reaction mechanisms are proposed (Scheme 3 and Scheme 4). 2-Carbonyl

Inherent atomic mobility changes in carbocation intermediates during the sesterterpene cyclization cascade

• Hajime Sato,
• Takaaki Mitsuhashi,
• Mami Yamazaki,
• Ikuro Abe and
• Masanobu Uchiyama

Beilstein J. Org. Chem. 2019, 15, 1890–1897, doi:10.3762/bjoc.15.184

• diphosphate, IM: intermediate. Quiannulatene is formed by the deprotonation of IM11. Phase (I): 5/12/5 tricycle formation is highlighted in blue. Phase (II): conformational changes and hydrogen shifts are highlighted in orange. Phase (III): ring rearrangements are highlighted in yellow. Reaction mechanisms of

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• of the common reactants with 2-aminopyridines/2-aminoquinolines/1-aminoisoquinolines 3, 75, 76 to give the desired products, respectively (Scheme 27). Both EWGs and EDGs on the reactants resulted in good to excellent yields of the product. This process followed two types of coupling reaction

• mechanisms, i.e., a Chan–Lam coupling and an Ullmann coupling. The Chan–Lam coupling involved a C–N bond formation (intermediate I, 84) which then entered into the Ullmann coupling to undergo intramolecular cyclization to form final product 78 and release Cu(III) to Cu(I) by reductive elimination. In this

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• intermolecular hydroarylation of allenes bearing electron-withdrawing substituents. Plausible reaction mechanisms have been proposed on the basis of the investigated reactions, and NMR analysis and DFT studies of the intermediate cationic species. Keywords: aluminum chloride; cation; intermediate

• achieved. This reaction gave rise to phosphoryl-substituted alkenes and indanes. The intermediates of these reactions were investigated by means of NMR and DFT calculations, that shed light on the reaction mechanisms. Allenes 1a–j used in this study. 31P NMR monitoring of the progress of transformation of

Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation

• Sebastian Haferkamp,
• Andrea Paul,
• Adam A. L. Michalchuk and
• Franziska Emmerling

Beilstein J. Org. Chem. 2019, 15, 1141–1148, doi:10.3762/bjoc.15.110

• reaction environment. It was subsequently demonstrated how a combination of different in situ methods can provide more thorough investigation of mechanochemical reaction mechanisms [14][15][16]. Of particular benefit to synthetic reactions, such as C–C bond formation [17][18], the use of Raman spectroscopy

SO₂F₂-mediated transformation of 2'-hydroxyacetophenones to benzo-oxetes

• Revathi Lekkala,
• Ravindar Lekkala,
• Balakrishna Moku,
• K. P. Rakesh and
• Hua-Li Qin

Beilstein J. Org. Chem. 2019, 15, 976–980, doi:10.3762/bjoc.15.95

• proposed to be E-configured. However, the exact configuration was not confirmed [40]. Two possible reaction mechanisms were proposed for this SO2F2-mediated transformation of 2'-hydroxyacetophenones to benzo-oxetes (Scheme 3). The first mechanism commences with the deprotonation of 2'-hydroxyacetophenone 1

• mmol, 3.0 equiv) in DMSO (2.0 mL) was stirred at 90 ° C under a SO2F2 atmosphere (balloon) for 20 h. Yields refer to isolated yields. aReaction performed at 50 °C. Two proposed reaction mechanisms. B = base. Screening and optimization of the reaction conditions.a Supporting Information Supporting

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• react only with the more distant glucose units, therefore only AC and AD disubstitution takes place. The detailed study of the reaction mechanisms is out of the scope of this paper, however, the different mechanisms and reaction intermediates are likely responsible for the distinct outcome of the two

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• , as shown in Figure 9. Consequently, the overall structures of compounds A and B are depicted in Figure S18 (Supporting Information File 1). Figure 10 shows the reaction mechanisms for generating compounds A and B from cichorinotoxin by treatment with dilute KOH. The proton at α-position of D

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis

• Ferran Planas,
• Michael J. McLeish and
• Fahmi Himo

Beilstein J. Org. Chem. 2019, 15, 145–159, doi:10.3762/bjoc.15.15

• , computational studies have been used to investigate full reaction mechanisms of ThDP enzymes, including pyruvate decarboxylase (PDC) [25][26][27][28], benzoylformate decarboxylase (BFDC) [29][30], acetohydroxy acid synthase [24][31][32][33][34][35], pyruvate dehydrogenase (PDH) [36], benzaldehyde lyase [37

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• ; L-proline; reaction mechanism; Introduction Electrospray (ESI) mass spectrometry (MS) [1] is well suited for studying reaction mechanisms as it is a soft ionization method leaving most species intact [1][2][3]. In addition, it is a fast analytical method [3] making it possible to study transient

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• mixtures, (arylsulfinyl)allenes give allyl alcohols (ArSO2–CR1=CH–C(OH)R2R3). Plausible reaction mechanisms have been proposed for all studied reactions. Keywords: (arylsulfinyl)allenes; (arylsulfonyl)allenes; butadienes; 1,2-oxathiolium ions; thiochromene 1,1-dioxides; Introduction Allenes are widely

• (CCDC 1843239); ellipsoid contours of probability levels are 50%. (Arylsulfinyl)allenes 1 and (arylsulfonyl)allenes 2 used in this study. Plausible reaction mechanisms of transformations of allene 2a in Brønsted acids. Selective formation of butadienes 3a–h from allenes 2a–h. Reactions of allenes 2 in

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• -enzymatic conditions offers good understanding of their elaborate reaction mechanisms. Furthermore, bio-inspiration offers a new approach to catalytic design for green and eco-friendly molecular transformations. As part of a study based on vitamin B12 derivatives including heptamethyl cobyrinate perchlorate

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• value of these methods to medicinal chemistry is considered. An overview of the general characteristics of the photocatalysts as well as some electrochemical data is presented. In addition, the general reaction mechanisms for organocatalysed photoredox transformations are discussed and some individual

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• misunderstandings from the reported covalent functionalization methods are discussed, and a direct link between the reaction mechanisms and the basic principles of organic chemistry is taken into special consideration. Keywords: characterization; functionalization; graphene; modification; synthesis design

• , reaction mechanisms, and state of the art of organic chemistry. Point-by-point recommendations are also given for the proper application of organic chemistry principles in covalent functionalization of graphene-family materials. The chemistry of the reactive groups of graphene-family materials covers many

• stacking. As mentioned above in the discussion of reaction mechanisms, water molecules significantly lower the reaction rates for the desired nucleophiles. Importantly, water molecules also influence the hydrolysis of the activated carboxyl groups (Figure 2, step d and Figure 3, step f). Water should

Cobalt-catalyzed C–H cyanations: Insights into the reaction mechanism and the role of London dispersion

• Eric Detmar,
• Valentin Müller,
• Daniel Zell,
• Lutz Ackermann and
• Martin Breugst

Beilstein J. Org. Chem. 2018, 14, 1537–1545, doi:10.3762/bjoc.14.130

• intermediates and transition states. Keywords: catalysis; C–H activation; density functional theory; London dispersion; reaction mechanisms; Introduction For a long time, large and bulky substituents have intuitively been considered to act through unfavorable steric interactions, although London dispersion

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• -oxytosylation of ketones by using a new family of chiral hypervalent iodine catalyst 21 with up to 46% ee [67]. The investigation of the reaction mechanisms revealed that the steric crowding around the iodine center improves the enantioselectivity (Scheme 18). Asymmetric oxygenation and nitrogenation reactions

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• matrix indicated that the dominant isomer was the same as was produced in entry 1, Table 3. Therefore, this analysis showed that the dominant enantiomer of 10 arose from an inversion, rather than retention, of configuration of the original stereocenter of 1. There may be four different reaction

• mechanisms operating in these Friedel–Crafts reactions as shown in Figure 4. (A) Coordination of the fluorine atom with the hydrogen bond donor, followed by backside attack of the nucleophile leads to SN2 reaction and inversion of configuration. (B) Hydrogen bond donor coordination to fluorine leads to

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• of the bisdioxines becomes severely hindered in cyclic derivatives, so that the 38-membered ring compound 32 requires microwave heating at 170 °C to form tetraoxaadamantane 33, and the catenated compound 36 and calix[6]arene derivative 37 did not form tetraoxaadamantanes. The reaction mechanisms of

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• dicyanofumarates and maleates as highly functionalized electron-deficient dipolarophiles, dienophiles and Michael acceptors is summarized. The importance for the studies on reaction mechanisms of cycloadditions is demonstrated. Multistep reactions with 1,2-diamines and β-aminoalcohols leading to diverse five- and

• [3 + 2]-cycloadditions with dialkyl dicyanofumarates E-1 and maleates Z-1 are important from the point of view of the interpretation of reaction mechanisms of cycloadditions. The results obtained with electron-rich thiocarbonyl S-methanides 16 demonstrate that the classical concerted mechanism

• isomeric homo-Diels–Alder adducts were found in the mixture. [3 + 2]-Cycloadditions (1,3-dipolar cycloadditions) Electron-rich 1,3-dipoles such as thiocarbonyl S-methanides and azomethine ylides react with dipolarophiles E-1 and Z-1 to give five-membered cycloadducts through stepwise zwitterionic reaction

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• mechanochemical reactions. A significant recent advance in mechanistic studies of mechanochemical reaction mechanisms was the introduction of techniques for in situ, real-time monitoring of ball milling processes [27], first through synchrotron X-ray powder diffraction (XRPD) [28][29], and later by Raman