A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• 22 with a catalytic amount of CB[8] as nanosized reaction vessels, which produced syn-photodimers 23 and 25 under light-irradiation as well as in sunlight (Figure 14) [47]. By gradually increasing the molar ratio of CB[8] (from 10 to 100 mol %), the conversion yield of the syn-products 23 (syn-HH

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• to undergo facile E/Z isomerization upon the absorption of UV photons, leading rapidly to a mixture of all four possible geometric isomers of 1 [15][16][17]. In the present work, this phenomenon was confirmed by exposing an ethanolic solution of 1 to sunlight for 2.5 h (Figure 3). The analysis of the

• product by 1H NMR spectroscopy revealed a multitude of new signals in the alkenyl region. In contrast, the analog 2 lacks conjugation in the central portion of the molecule and was therefore expected to be more stable to UV light. Indeed, the exposure of 2 to sunlight in an identical manner to that

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

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• 1а with pinacol 2-phenylethynyl boronate. The meta-methoxystyryl derivative 5c was found to easily undergo photodimerization in solid state upon sunlight exposure, leading to the formation of compound 8 with a central cyclobutane ring (see Supporting Information File 1). As proved previously for

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• , light is inexpensive, nontoxic, noncontaminating, ample (or “limitless” in the case of sunlight) and a renewable source of energy for environmentally-friendly and “green” chemical synthesis. As a consequence of comprehending the detrimental impact of human industry on the environment, new methods to

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• without noticeable decomposition. However, in solution under ambient atmosphere and sunlight decomposition takes place quickly, which is indicated by decolorization of a purple solution in CH2Cl2 within 3 min. 1H NMR analysis showed 6,13-pentacenequinone (15) as the degradation product. The rate of

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

• observed that crystals of santonine would shatter when exposed to sunlight [28]. Credit for the pioneering of photochemistry is usually given to Ciamician, the “grandfather of photochemistry”, who reported many interesting transformations of chemical solutions when irradiated by sunlight [29][30]. His

• irradiated with sunlight [74]. The use of titania as a pigment had been practiced for centuries, and the observation that TiO2-based surface coatings exposed to sunlight irradiation would “chalk” (the formation of a loose white powder on the paint surface) had been recognised as the decomposition of organic

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• inexpensive visible light (or sunlight, when possible) irradiation [29]. In general terms, photocatalysis smoothly gives access to reactive radical intermediates [30], mainly carbon-centered [31][32][33], or nitrogen-centered radicals [34][35]. In turn, these species have been extensively employed in radical

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• garden under sunlight irradiation; notably, ascaridole is an effective anthelmintic natural drug obtained in this protocol from another readily available natural product α-terpinene. Several other approaches have been described in both synthesis and derivatizations of ascaridole. However, the Meunier

• porphyrins as photocatalysts under sunlight irradiation furnished the corresponding sulfoxides with high chemoselectivity (up to 100%), scalability (up to 2.6 mmol) and high yields (up to 100%) [94]. According to the authors, the protonation of the porphyrins causes a red-shift of the photosensitizer with an

• increase of singlet oxygen generation and photocatalytic activity under the sunlight irradiation. Furthermore, the steric hindrance around the porphyrin core, caused by the diacids, enhanced the catalyst photostability, allowing a lowers porphyrin load. The authors evaluated various protonated-TPPs, using

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

• energy [54]. The aromatic carbonyl compounds were dissolved in isopropanol and exposed to direct sunlight for 7–10 days to give the corresponding 1,2-diols 92 in high to moderate yield. The excitation of the carbonyl compound 87 was followed by hydrogen atom abstraction from the solvent 89, affording the

• seek greener and sustainable processes to advance chemistry, the use of aldehydes in conjunction with light irradiation, even sunlight, will become more popular, providing a vast array of applications. Norrish type I and II dissociations. Proposed radical pair formation after the photolysis of

Synthesis and herbicidal activities of aryloxyacetic acid derivatives as HPPD inhibitors

• Man-Man Wang,
• Hao Huang,
• Lei Shu,
• Jian-Min Liu,
• Jian-Qiu Zhang,
• Yi-Le Yan and
• Da-Yong Zhang

Beilstein J. Org. Chem. 2020, 16, 233–247, doi:10.3762/bjoc.16.25

• of HPPA to HGA is interfered with an HPPD inhibitor [9][10]; consequently, plants become severely damage when exposed to sunlight, ultimately resulting in bleaching symptoms followed by necrosis and death [11][12]. Therefore, HPPD inhibitors play important roles in the herbicide industry. In addition

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

Naphthalene diimides with improved solubility for visible light photoredox catalysis

• Barbara Reiß and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 2043–2051, doi:10.3762/bjoc.15.201

• sustainable method for catalysis because sunlight is an essentially unlimited and thereby “green” natural light source and LEDs – conveniently used for irradiation experiments in the laboratory – are cheap and energy-saving artificial sources for irradiations. The current “working horse” for photoredox

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• and 4, explaining the deeper unoccupied levels in the former molecules. Thus, our calculations suggest that, in case of an allowed HOMO–LUMO transition, 1 and 3 should show a bathochromically shifted optical absorption spectrum, thereby hopefully allowing for a more efficient sunlight absorption, yet

Synthesis and biological investigation of (+)-3-hydroxymethylartemisinin

• Toni Smeilus,
• Farnoush Mousavizadeh,
• Johannes Krieger,
• Xingzhao Tu,
• Marcel Kaiser and
• Athanassios Giannis

Beilstein J. Org. Chem. 2019, 15, 567–570, doi:10.3762/bjoc.15.51

• containing methylene blue as photosensitizer was exposed to sunlight and oxygen. The treatment of the resulting intermediate hydroperoxide with a small amount of trifluoroacetic acid as previously described [17][18], afforded in the frame of a Hock cleavage (+)-3-hydroxymethyl-9-desmethylartemisinin (16) in

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• now possible to perform photopolymerizations upon soft irradiation conditions with, for example, household light bulbs, LED light, low intensity lasers and even sunlight [1][2][3][4]. The first reason is the low cost and infiniteness character of light (more particularly when using visible light). The

• interest for catalytic reduction of hydrogen gas [64]. Such an iron polypyridyl complex has also really good photoredox catalyst properties to initiate a polymerization upon sunlight exposure in a three-component system [68]. Functionalization of the ligand can change the photochemical properties of the

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

• damaging and toxic to various life forms. Photochemistry also offers benefits compared to conventional thermally driven processes. Several transformation processes that utilise sunlight as the energy source to drive a particular reaction have been reported and some reactions presented in this review

• possible to carry out these reactions using sunlight as the source of photons, leading them to term their newly discovered photocatalyst a “minimalistic chemical model of the Z-scheme in biological photosynthesis”. The König group has contributed a more traditional methodology as well, publishing a

• ) using atmospheric oxygen as the stoichiometric oxidant, TBA-Eosin Y photocatalysis and carbonate as the base at room temperature (Scheme 23) [68]. The group also reported that this transformation is possible using sunlight as the source of photons, with a yield comparable to that obtained when blue LEDs

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

• TBAB/K2S2O8 at 90 °C [31], the cyanomethyl-radical-mediated reaction of aryl 2-alkynoates with tert-butyl peroxybenzoate (TBPB)/acetonitrile at 130 °C [32], the sunlight-promoted reaction of aryl 2-alkynoates with N-iodosuccinimide (NIS) at rt [33], and the visible-light-mediated reaction of aryl 2

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• their 13C NMR spectra, respectively. Small amounts (<10%) of non-volatile toluene derivatives were occasionally detected in the crude products by 1H NMR spectroscopic analysis but no attempts were made to isolate these compounds. The reaction was additionally studied with natural sunlight [51][52

• ]. Solutions of 1a and 2a were exposed to direct sunlight in a solar float developed by Liu and co-workers [53][54]. After 6 hours of illumination, the reaction had reached a conversion of 47% and 3a was subsequently isolated by column chromatography in 26% yield (Table 2, entry 18). The structures of the

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• dichloromethane (DCM), acetone (DMK), benzene, tetrahydrofuran (THF), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), but are poorly soluble in hot ethanol and not soluble in hexane. On the enlargement of the conjugated system the colour of the compounds solutions in the sunlight expectedly changes from

Cycloheximide congeners produced by Streptomyces sp. SC0581 and photoinduced interconversion between (E)- and (Z)-2,3-dehydroanhydrocycloheximides

• Li Yang,
• Ping Wu,
• Jinghua Xue,
• Huitong Tan,
• Zheng Zhang and
• Xiaoyi Wei

Beilstein J. Org. Chem. 2017, 13, 1039–1049, doi:10.3762/bjoc.13.103

• (extraction and fractionation), with neither direct sunlight shining into nor any artificial high-energy light being applied in the laboratory, we doubted if the fast conversion was induced by our laboratory indoor light. Thus, compounds 2 and 3 in the mixture were separated by preparative HPLC and their MeOH

Chemoselective synthesis of diaryl disulfides via a visible light-mediated coupling of arenediazonium tetrafluoroborates and CS₂

• Jing Leng,
• Shi-Meng Wang and
• Hua-Li Qin

Beilstein J. Org. Chem. 2017, 13, 903–909, doi:10.3762/bjoc.13.91

• transformation of carbon disulfide into diaryl disulfides [11]. Sunlight as abundant and almost infinitely available energy resource has been widely used for chemical transformations in the sense of cost, safety, availability, and environmental friendliness [12][13][14][15]. Herein, we report a visible light

• turns red upon exposure to sunlight due to decomposition and formation of radical species [20]. Subsequently, the photodecomposition of diazonium salts by loss of nitrogen upon exposure to light has been utilized in organic synthesis for example to remove amino groups from anilines [21] or for arylation

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• electrons and holes for the collection at the electrodes once generated after absorption of sunlight. Figure 7 shows the current–voltage characteristics in the dark and after illumination with AM 1.5G (100 mW cm−2) for devices with P1, P2, and P3. The photovoltaic parameters of the devices are summarized in

• polymers P1–P3 and polymer:PC70BM blends. Bulk heterojunction solar cells device architecture, illustrating favorable conditions for absorption of sunlight. J–V Spectra in chlorobenzene (CB) for which the ratio of polymer:PC70BM was optimized as follows: P1:PC70BM, 1:3; P2:PC70BM, 1:1.5; P3:PC70BM, 1:3

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• , aromatisation and carbonisation to yield CDs. The resulting cyclodextrin-derived CDs were then used for the detection of Ag+ ions in solution. It was found initially that mixing AgNO3 in an aqueous solution of CDs in sunlight resulted in the formal reduction of Ag+ to elemental Ag0, which was thought to proceed

• via the adhesion of Ag+ to the CD surface, followed by reduction in the presence of sunlight, which promotes the excitation of the reducing electron to a higher energetic state (Scheme 23). Through UV–vis absorbance and TEM measurements it was evident that a surface layer of plasmonic Ag existed on