Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• suppress the photochemical reaction while carrying out another light-induced transformation. Aromatic additives (Table 2): In parallel we observed the significant influence on the reaction rate when the substrate contained an aromatic moiety (e.g., the thioanisole oxidation is over 10 times faster than the

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• more preferable process compared to aromatization. The above-mentioned photochemical reaction of pyrimidines 10 allows to synthesize polycyclic products 12 (Scheme 8, method A). In this case, the yields of compounds 12 did not exceed 41%, which is associated with low regioselectivity of the process and

Flow synthesis of oxadiazoles coupled with sequential in-line extraction and chromatography

• Kian Donnelly and
• Marcus Baumann

Beilstein J. Org. Chem. 2022, 18, 232–239, doi:10.3762/bjoc.18.27

• ]pentane (BCP) building blocks [36], we investigated their use in the oxadiazole-forming reaction. The BCP acid chloride 5 was synthesised from [1.1.1]propellane (3) via the photochemical reaction with isopropyl 2-chloro-2-oxoacetate (Scheme 4). The corresponding BCP acyl hydrazone was then obtained

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• studies into this reaction demonstrate two mechanistically distinct photocleavage pathways, with selectivity dependent on pH. In addition to an anticipated alkenyl sp2 C–X bond cleavage pathway, we identified a new photochemical reaction pathway, prevalent under neutral and acidic reaction conditions

1,2,3-Triazoles as leaving groups in S_NAr–Arbuzov reactions: synthesis of C6-phosphonated purine derivatives

• Kārlis-Ēriks Kriķis,
• Irina Novosjolova,
• Anatoly Mishnev and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 193–202, doi:10.3762/bjoc.17.19

• -phosphonate synthesis. They can be obtained by 1) the reaction of a lithiated C8 position with diethyl chlorophosphate (C→D, Scheme 1) [14] and 2) an intermolecular [15] or intramolecular [16] photochemical reaction between 8-bromopurine derivatives and phosphite (E→F and G→H, respectively, Scheme 1). Further

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• selection of a proper light source needs to be considered. The reactor material should be inert to the reaction medium and transparent to the wavelength range that drives the photochemical reaction. Ideally, the light source should emit light only in the wavelength range of interest and should have a high

• flow, which is characterized by the regularly sized bubbles surrounded by liquid slugs. The light distribution is affected by the presence of bubbles in the Taylor flow. In a recent study, a photochemical reaction model was developed to optimize the performance of reactors that use a Taylor flow in a

Formation of an exceptionally stable ketene during phototransformations of bicyclo[2.2.2]oct-5-en-2-ones having mixed chromophores

• Asitanga Ghosh

Beilstein J. Org. Chem. 2020, 16, 2297–2303, doi:10.3762/bjoc.16.190

• given in Table 1. Synthesis of 7a,b. Photochemical reaction of 7a,b; a) solvent and conditions are given in Table 2. Conversion of ketene 10a to its methyl esters 11a,b. Chemical yields of the formation of photoproducts 4, 5 and 6. Result of photoreaction of 7a,b at various wavelengths in different

A method to determine the correct photocatalyst concentration for photooxidation reactions conducted in continuous flow reactors

• Clemens R. Horn and
• Sylvain Gremetz

Beilstein J. Org. Chem. 2020, 16, 871–879, doi:10.3762/bjoc.16.78

• photochemical reaction, the often overlooked key reagent is, in fact, the light, and through the subsequent interaction between light and the photocatalyst, the light is transformed. Following this logic led to the observation that one needs to more carefully consider not only the concentration of the catalyst

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• transferred to the olefins in the Paterno–Büchi reaction, they performed a photochemical reaction between benzaldehyde (8) or benzophenone and the 3-methyl-2-pentenes 69 and 70, respectively. The isomerization of the starting olefins indicated a bimolecular energy transfer mechanism (Scheme 17). Benzophenone

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• excited state possesses several competitive reaction pathways for deactivation. This is a photochemical reaction such as photoinduced electron transfer serving as source to generate reactive intermediates such as initiating radicals or conjugate acid [5]. Photophysical events of S1 occurring after one

Recent developments in photoredox-catalyzed remote ortho and para C–H bond functionalizations

• Rafia Siddiqui and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 248–280, doi:10.3762/bjoc.16.26

• into chemical energy via the generation of reactive intermediates through electron transfer reactions. A photochemical reaction is directed by the photophysical properties of an electronically excited molecule. The first vibrational equilibrated singlet excited state is S1, and it depends on both

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• a monofluoro-AB (1FAB) [18]. Spectra in HEPES, pH 7.4 at rt. Photochemistry of 4FABTA (2), and thermodynamic stability in physiological buffer. a) Trans–cis photochemical reaction of 2. b) Absorption spectra of all trans-2 (black), cis-2 PSS (from 532 nm laser), and trans-2 PSS (from 405 nm laser

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• ]. For that reason, for our optimization studies we used enantioenriched aldehyde 1 (S/R 2:1 mixture of enantiomers) formed in the photochemical reaction of cinnamaldehyde (12) with benzyltrimethylsilane (BnTMS, 13) catalyzed by commercially available imidazolidinone cis-14 (Scheme 3) [16]. Aldehyde 1

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• Information File 1, Figures S1 and S12). By introduction of fluorine atoms ortho to the azo bond, the two n→π* of E- and Z-state become sufficiently separated to address them individually using visible light sources. Along with averting UV light for the photochemical reaction, high PSS ratios can be observed

Norbornadiene-functionalized triazatriangulenium and trioxatriangulenium platforms

• Roland Löw,
• Talina Rusch,
• Tobias Moje,
• Fynn Röhricht,
• Olaf M. Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1815–1821, doi:10.3762/bjoc.15.175

• s−1 under air and 0.95·10−3 s−1 under nitrogen. Hence, the thermal reaction (in contrast to the photochemical reaction) is not largely affected by oxygen. The half-life of the metastable quadricyclane is t1/2 = 655 h in benzene under air at 293 K (Table 1). Minor amounts of degradation products (<1

Photochemical generation of the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical from caged nitroxides by near-infrared two-photon irradiation and its cytocidal effect on lung cancer cells

• Ayato Yamada,
• Manabu Abe,
• Yoshinobu Nishimura,
• Shoji Ishizaka,
• Masashi Namba,
• Taku Nakashima,
• Kiyofumi Shimoji and
• Noboru Hattori

Beilstein J. Org. Chem. 2019, 15, 863–873, doi:10.3762/bjoc.15.84

• ultraviolet (355 nm) irradiation (Scheme 1) [33]. De-aerated conditions are necessary for the triplet-sensitized generation of TEMPO due to the triplet quenching ability of O2. The polymerization reactions were initiated via photochemical reaction [34][35][36]. For physiological studies, however, the

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• importance, since the highly reactive intermediate can be generated by photochemical reaction such as electron transfer and energy transfer [43][44][45]. Among them, light-energy-driven CO2 fixation reactions via C–C bond formation are promising in terms of mimicking photosynthesis. In 2015, Murakami et al

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• irradiation conditions one can direct the photochemical reaction of diazo compounds at the alternative way, which provides the retention of ‘dinitrogen’ in the structure of molecule formed. It is reasonable that a question arises on the scope and limitations of this new light-induced reaction of diazo

• yields of hydrazones 2, an effort was undertaken to optimize the photochemical reaction conditions by varying the wavelength of irradiation, sensitizer, as well as the ratio of sensitizer/diazodiketone 1b (Table 1, entries 4–9). As can be seen from the data in Table 1 the most effective sensitizer for

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• its slow decomposition to pyrazole and CO2. Such ambiguous substitution effects are therefore worthy of further investigations. Photochemical reaction of sydnones with symmetrical alkynes In 1966 Krauch et al. [59] dealt with irradiation (using a high-pressure Hg lamp) of benzene or dioxane solutions

• their corresponding trimethylsilyl triflates was recently used by Garg et al. [115] and Bräse et al. [116] in expanding the utility of oxygen- or nitrogen-containing strained heterocycloalkynes (Scheme 15) but the regioselectivity was poor in most cases. Photochemical reaction of sydnones with non

• -symmetrical alkynes As mentioned in the previous section, Gotthardt and Reiter [63][64] studied the photochemical reaction of sydnones with terminal alkynes. They have also studied the reaction with phenylacetylene, methyl propiolate and ethyl phenylpropiolate in a batch reactor under irradiation with 300 nm

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• acid-catalyzed reaction of phenols and propynoic acids [22] and the (−)-riboflavin-catalyzed photochemical reaction of cinnamic acids [23] were reported recently. Moreover, the use of radical cyclization for the construction of the coumarin skeleton has become widespread. Examples include the radical

Chemical systems, chemical contiguity and the emergence of life

• Terrence P. Kee and
• Pierre-Alain Monnard

Beilstein J. Org. Chem. 2017, 13, 1551–1563, doi:10.3762/bjoc.13.155

• ]. Such vesicles with associated ribozymes could eventually prove to be novel functional chemical systems. The production of fatty acids from non-amphiphilic picolylesters performed using a photochemical reaction involving a ruthenium tris(bipyridine), functioning as photosensitizer and redox catalyst

Automating multistep flow synthesis: approach and challenges in integrating chemistry, machines and logic

• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2017, 13, 960–987, doi:10.3762/bjoc.13.97

• , electrochemical reaction, photochemical reaction, microwave, etc. On the other hand, it is also possible and in many times necessary to classify the reactions on the basis of the number of phases (gas G, liquid L, and solid S) involved in the reaction (viz. single-phase or homogeneous reaction and multiphase

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• has led to uncertainty in quantifying the true effect of isoprene on the NOx cycle and subsequent O3 enhancement. Shepson et al. sought to deconvolute this process replicating the atmospheric synthesis of IPN using a photochemical reaction chamber to determine IPN yield from isoprene photooxidation

• nitrates underwent rapid pseudohydrolysis; a process that generates corrosive nitric acid and non-volatile SOA [13]. Similar to the isoprene studies by Pye et al. the role of organic nitrates derived from terpenes is starting to gain traction. Rindelaub et al. undertook a photochemical reaction chamber

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• a molecular form of 1 produced azepine 3 (path II) by irradiation. The detailed mechanism of the formation of 3 is shown in Scheme 2. Thus, in the photochemical reaction both ionic and molecular forms of 1 can be used. To increase the yield of 2, it is necessary to shift the equilibrium towards the

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• -orbitals of the double bonds are hence prevented from overlap [1][2]. So far we have only been successful in observing a single photochemical reaction between 19 and an “external” reagent: the photoaddition of oxygen to its unhindered, inner diene unit. After 20 h irradiation with a daylight lamp in