Understanding X-ray-induced isomerisation in photoswitchable surfactant assemblies

• Beatrice E. Jones,
• Camille Blayo,
• Jake L. Greenfield,
• Matthew J. Fuchter,
• Nathan Cowieson and
• Rachel C. Evans

Beilstein J. Org. Chem. 2024, 20, 2005–2015, doi:10.3762/bjoc.20.176

• species produced on water radiolysis may therefore play a complicated role in inducing Z–E isomerisation via a number of different mechanisms. No matter the mechanism, the morphology changes on X-ray irradiation appear consistent with the hypothesis that the E isomer is reformed, as shown by the return of

Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• either 1) covalent functionalization of the fullerene surface with polar moieties or 2) complexation with water-soluble host molecules or polymers. Related to the former approach, the Nakamura group [11], Wudl group [12], and Hirsch group [13] reported initial work in the early 1990s on water-soluble C60

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding

• Stiliyana Pereva,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2019, 15, 1592–1600, doi:10.3762/bjoc.15.163

• against experimental data (dissociation energy, D0, in the gas phase) on water dimer. Frequency calculations for each M062X/6-31G(d,p) optimized construct were performed at the same level of theory. No imaginary frequency was found for the lowest energy configurations of any of the optimized structures

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• environmentally oriented efficient organocatalysts with prominence “on-water conditions” [30][31]. It is known that an important condition for an organic reaction in water is the aggregation of the reactants and the catalyst by hydrophobic forces. Further, the potential of hydrogen-bond donation may be a vital

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• H2O (ca. 6%) severely affects the phosphine-based catalysts Caz-I and Ind-II, while it has a less pronounced detrimental effect on the isopropyloxy-benzylidene catalyst HG-II. “On water” vs “in water” metathesis Hydrophobic catalysts are able to perform metathesis in aqueous mixtures. Blechert and

• on the catalytic activity of the reaction. In fact, catalyst and substrate are encapsulated into emulsion droplets formed in the reaction media above the aqueous layer, making the reaction proceed “on water” [21][22]. The introduction of amphiphilic molecules for aqueous micellar catalysis allows

Ammonium-tagged ruthenium-based catalysts for olefin metathesis in aqueous media under ultrasound and microwave irradiation

• Łukasz Gułajski,
• Andrzej Tracz,
• Katarzyna Urbaniak,
• Stefan J. Czarnocki,
• Michał Bieniek and
• Tomasz K. Olszewski

Beilstein J. Org. Chem. 2019, 15, 160–166, doi:10.3762/bjoc.15.16

• Marcus postulated a trans-phase hydrogen bonding from water OH groups to H-bond acceptor sites of organic reactants contributing to a stabilisation of organic transition states enables the on-water catalysis [77]. Ben-Amotz et al. demonstrated that the effect of the water OH groups depends either on the

Catalyst-free synthesis of 4-acyl-NH-1,2,3-triazoles by water-mediated cycloaddition reactions of enaminones and tosyl azide

• Lu Yang,
• Yuwei Wu,
• Yiming Yang,
• Chengping Wen and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2018, 14, 2348–2353, doi:10.3762/bjoc.14.210

• , authentically mild conditions (40 °C stirring) as well as practical scalability. Keywords: additive-free; catalyst-free; cycloaddition; enaminones; on water; 1,2,3-triazole; Introduction Discovering sustainable chemical syntheses constitutes one central issue of modern organic chemistry. A large number of

• environmentally benign alternative to organic solvents, on water reactions are known for their accelerated reaction rates and improved synthetic selectivity [4][5][6]. Being inspired by these commonly recognized green features, flourishing advances in the research of water-mediated or promoted organic syntheses

• heterogeneous “on water” process (Scheme 1). Based on the known works employing organic solvents for similar synthesis and the present results [55], a possible mechanism for the reaction is proposed (Scheme 2). The reaction starts from the cycloaddition of enaminones 1 and tosyl azide (2) to provide 1,2,3

Correlation of surface pressure and hue of planarizable push–pull chromophores at the air/water interface

• Frederik Neuhaus,
• Fabio Zobi,
• Gerald Brezesinski,
• Marta Dal Molin,
• Stefan Matile and
• Andreas Zumbuehl

Beilstein J. Org. Chem. 2017, 13, 1099–1105, doi:10.3762/bjoc.13.109

• intensity up to 20 mN/m indicates an increase of the effective layer thickness. It is important to note that the OH-band intensity does not change during expansion. Isotherms of DPPC (dark blue), cholesterol (magenta), DPPC/cholesterol (8:2 mol/mol, green), and DPPC/flipper (8:2 mol/mol, blue) measured on

• water at 25 °C. The area in the mixture is given as area per DPPC molecule. Correlation of the hue of a monolayer flipper probe with its measured surface pressure at the water/air interface at 20 °C subphase temperature and 22 °C air temperature. Supporting Information Supporting Information File 224

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• ) [121][177][178], several other amphiphiles that are both less costly and are items of commerce gave comparable results. Using commercialy available Brij 35 (2 wt %) in water [179][180][181][182][183] afforded the best levels of conversion and thus, overall yields, while in its absence (i.e.,”on water

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

• on water, the supramolecular chemists mostly agreed that water was not a special solvent, it just occupied an extreme, with low polarizability and a high cohesive nature. In stark contrast, the physical chemists showed plots indicating that water was unlike any other liquid and was clearly special

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• ][36]. Moreover, their stability allows to perform reactions under mild and aerobic conditions and in the presence of water, both as co-solvent or the only solvent [37]. In the last years, several reports on water effects in organocatalytic reactions were published [38][39][40][41][42]. The use of

Oxidative phenylamination of 5-substituted 1-hydroxynaphthalenes to N-phenyl-1,4-naphthoquinone monoimines by air and light “on water”

• Julio Benites,
• Juan Meléndez,
• Cynthia Estela,
• David Ríos,
• Luis Espinoza,
• Iván Brito and
• Jaime A. Valderrama

Beilstein J. Org. Chem. 2014, 10, 2448–2452, doi:10.3762/bjoc.10.255

• by on-water oxidative phenylamination of 1,5-dihydroxynaphthalene (1) and 5-acetylamino-1-hydroxynaphthalene (5) with oxygen-substituted phenylamines under aerobic conditions and either solar or green LED radiation, in the presence of rose bengal as singlet oxygen sensitizer. As compared to the

• conventional oxidative phenylamination procedures, this novel synthetic method offers the advantage of aerobic conditions “on water” instead of hazardous oxidant reagents currently employed in aqueous alcoholic media. Keywords: 1,4-naphthoquinone monoimines; on water; oxidative coupling; rose bengal; solar

• phenylamines “on water” [8] represent two valuable examples on the scope of green methodologies in the field of quinone synthesis. 1,4-Naphthoquinones possessing a substituted amino group in the 2-position have been the subject of study for many years due to their use in a variety of medical and biological

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

• copper(I) complexes, which are highly active in CuAAC reactions on water or under neat conditions (Scheme 7) [130]. Albeit no single crystals of the copper(I) complex shown in Scheme 7 could be grown, NMR measurements as well as a single crystal X-ray structure of an analogous C186tren-complex with CuCl2

The myxocoumarins A and B from Stigmatella aurantiaca strain MYX-030

• Tobias A. M. Gulder,
• Snežana Neff,
• Traugott Schüz,
• Tammo Winkler,
• René Gees and
• Bettina Böhlendorf

Beilstein J. Org. Chem. 2013, 9, 2579–2585, doi:10.3762/bjoc.9.293

• ); ESIMS(−) m/z: 693.3 [2M − H]−, 346.2 [M − H]−; ESIMS(+) m/z: 348.2 [M + H]+. Biological testing. Cut leaf disks (15 mm2) of the respective host plants (see below) were placed on water agar in multi-well plates (24-well format) and sprayed with 12 µL aqueous test solution of varying concentrations (dose

Interaction of cyclodextrins with pyrene-modified polyacrylamide in a mixed solvent of water and dimethyl sulfoxide as studied by steady-state fluorescence

• Akihito Hashidzume,
• Yongtai Zheng and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1312–1317, doi:10.3762/bjoc.8.150

• variety of fields, including food additives, cosmetics, and personal care items [6][7][8][9][10][11][12]. In the past decade, the formation of inclusion complexes of CDs with guest residues attached on water-soluble polymers has attracted increasing interest from a number of research groups because these

Building photoswitchable 3,4'-AMPB peptides: Probing chemical ligation methods with reducible azobenzene thioesters

• Gehad Zeyat and
• Karola Rück-Braun

Beilstein J. Org. Chem. 2012, 8, 890–896, doi:10.3762/bjoc.8.101

• azobenzene ligation peptide 14. Our future efforts directed towards the synthesis of photoswitchable peptides will focus on water-soluble 3,4'-AMPB building blocks being applicable in native chemical ligation methods in aqueous media. Structures of azobenzene thioesters, Nα-ligation auxiliaries and peptides

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• (Scheme 12) [49]. Recently, Cozzi et al. showed that FC benzylations can proceed even without adding a Lewis acid catalyst, just “on water” at 80 °C. However, this method is restricted to reactive heteroarenes such as indole (30), pyrrole and nucleophiles including azides or acetylacetonates. Moreover

• “on water”. Reductive FC alkylation of arenes with benzaldehyde and acetophenone catalyzed by the Ir-carbene complex 33. Formal synthesis of 1,1-diarylalkanes from benzyl alcohols and styrenes. (A) Mo-catalyzed hydroarylation of styrenes and cyclohexenes. (B) Hydroalkylation–cyclization cascade

Hydrogen bonding patterns in the cocrystals of 5-nitrouracil with several donor and acceptor molecules

• Reji Thomas,
• R. Srinivasa Gopalan,
• G. U. Kulkarni and
• C. N. R. Rao

Beilstein J. Org. Chem. 2005, 1, No. 15, doi:10.1186/1860-5397-1-15

• molecule engage two water molecules, while the two lone-pairs of the oxygen act as acceptors bringing in two more water molecules (Figure 10). The O...O distances are in the 2.73 – 2.83 Å range, comparable to the values obtained by abinitio calculations on water oligomers. [39][40] Three of the H-O-H