Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• -[18F]fluorophenylalanines 72a,b [54] were achieved by a copper-mediated nucleophilic radiofluorination of arylstannanes 71a,b with [18F]KF (Scheme 17). 1.6. Alkylation of benzophenone imine of glycine ester Pentafluoro-ʟ-phenylalanine (77a) and 2,4-ditrifluoromethyl-ʟ-phenylalanine (77b) were

• synthesized through alkylation of the benzophenone imine of glycine ester 73, with perfluorinated benzylbromide 19c or 2,4-bis(trifluoromethyl)benzyl bromide (74) in the presence of 2,7-bis[O(9)-allylhydrocinchonidinium-N-methyl]naphthalene dibromide, to afford the fluorinated phenylalanine imines 75a,b with

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

• capable to induce other types of reactions, such as hydrogen atom abstraction (HAT) processes or triplet state energy transfer processes (EnT). Carbonyl compounds, especially diaryl ketones, have shown great potential as far as their catalytic scope is concerned. Benzophenone or acetophenone (64) and

• that did not react with the excited benzaldehyde (9, Scheme 2). Photoorganocatalysts are known for their ability to abstract hydrogen atoms from various substrates, furnishing radical species. Benzophenone is a very well-studied example of this category. Alongside with benzophenone and acetophenone

• , McGinniss and co-workers reported the polymerization of methyl methacrylate (26, MMA) by employing 4,4’-bis(N,N-diethylamino)benzophenone (27, DEABP) as the photoinitiator (Scheme 7) [35]. It was already well-accepted that aminoaromatic compounds, such as Michler’s ketone (28) and DEABP (27), present large

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

• -free ATRP strategy [132][133][134][135][136][137]. Latter reference provided a comprehensive overview demonstrating the function of phenothiazine derivatives, perylene, diaryl dihydrophenazines, anthracene or pyrene. In addition, type II photoinitiators including benzophenone, and thioxanthones were

Formal preparation of regioregular and alternating thiophene–thiophene copolymers bearing different substituents

• Atsunori Mori,
• Keisuke Fujita,
• Chihiro Kubota,
• Toyoko Suzuki,
• Kentaro Okano,
• Takuya Matsumoto,
• Takashi Nishino and
• Masaki Horie

Beilstein J. Org. Chem. 2020, 16, 317–324, doi:10.3762/bjoc.16.31

• RINT-2000(CuKα) device. Concerning the solvent of the nickel- and palladium-catalyzed reactions, THF (anhydrous grade) was purchased from Kanto Chemical Co. Ltd. and passed through alumina and copper columns (Nikko Hansen & Co. Ltd.) or distilled from a sodium dispersion in mineral oil/benzophenone

Synthesis and optoelectronic properties of benzoquinone-based donor–acceptor compounds

• Daniel R. Sutherland,
• Nidhi Sharma,
• Georgina M. Rosair,
• Ifor D. W. Samuel,
• Ai-Lan Lee and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2019, 15, 2914–2921, doi:10.3762/bjoc.15.285

• Table 2. In the absorption spectra, 2 and 5 both showed intense π–π* absorption bands localized on the benzophenone at 326 and 310 nm, respectively [37]. The extra TPA donor in 5 contributed to a red-shifting of this absorption band. There were low-energy CT bands from the TPA donor to the BQ acceptor

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• . Commercially available reagents and solvents were used as received unless otherwise stated. THF and diethyl ether were distilled over sodium/benzophenone. Acetonitrile and dichloromethane were distilled over calcium hydride immediately before use. Compounds 1a and 2 were synthesized according to literature

• argon over sodium benzophenone ketyl. CH2Cl2 was distilled over CaH2 under argon. Mass spectrometry was performed at the CESAMO analytical center (University of Bordeaux, France) on a QStar Elite mass spectrometer (Applied Biosystems). The instrument is equipped with an electrospray ion (ESI) source and

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• the Re-face in both cases (Scheme 58). Magdesieva and his group developed an electrochemical method for the deprotonation of a Ni(II) glycinate complex containing (S)-o-[N-(N-benzylprolyl)amino]benzophenone [(S)-BPB] 188 as an chiral auxiliary moiety and explored its applicability in

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• mass spectra were calibrated externally, and a linear calibration was applied. All chemicals were reagent grade and were used without further purification. Tetrahydrofuran was dried by heating under reflux over sodium wire in the presence of benzophenone as indicator while dimethylformamide was dried

One-pot activation–alkynylation–cyclization synthesis of 1,5-diacyl-5-hydroxypyrazolines in a consecutive three-component fashion

• Christina Görgen,
• Katharina Boden,
• Guido J. Reiss,
• Walter Frank and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 1360–1370, doi:10.3762/bjoc.15.136

• -dione (3a) revealed that the use of KOH dried triethylamine instead of the initial preconditioning (Na/benzophenone dried) led to a reduction of the reaction time t1 from 24 to 15 h (see Supporting Information File 1, Table S1). In addition, the concentration could be doubled and the obtained yield of

Synthesis of the aglycon of scorzodihydrostilbenes B and D

• Katja Weimann and
• Manfred Braun

Beilstein J. Org. Chem. 2019, 15, 610–616, doi:10.3762/bjoc.15.56

• benzophenone until the dark blue color of the solution persisted. Then, the solvents were distilled under nitrogen and taken from the distillation flask, which was closed by a septum, by syringes or cannulas. 2,5-Dimethoxyacetophenone (6c) and 4-methoxystyrene (7b) were purchased from Sigma-Aldrich. 2,5

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• groups were removed by concentrated acid. A very efficient synthesis of (2S,3S,4S)-4 starts from another serine-derived chiron, namely O-benzyl-N-Boc-D-serine [111], which was readily transformed to the Z-olefin 120 containing a benzophenone imine residue as a nitrogen protecting group (Scheme 29

• of (+)-polyoxamic acid (Scheme 30) [113]. To this end the anion generated from benzophenone imine of tert-butyl glycinate 124 acted as a Michael donor in the presence of homochiral catalyst to give a ca. 1:1 mixture of diastereoisomeric iminoselenides 125 with an ee up to 96% (Scheme 30). Next, a 9

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• bromopyridines were reacted with benzophenone followed by a reaction of the lithiated alcohol with 2. Four new ruthenium alkylidene complexes, i.e., 6–9 (Figure 4), were successfully obtained and investigated as precatalyst in 1-octene metathesis in the temperature range 40–110 °C. The stability, selectivity and

• time 10 min); 110 to 290 °C at 25 °C/min (hold time 16 min). Reagents: 2-Bromo-3-methylpyridine (95%), 2-bromo-4-methylpyridine (97%), 2-bromo-5-methylpyridine (98%), 2-bromo-3-methoxypyridine (97%), n-BuLi (2.5 M in hexane), benzophenone (99%), 2-N,N-dimethylaminoethanol (≥ 99.5%), Grubbs 2 (2) (97

• %), 1-octene (99% GC), nonane (reagent plus 99%) and toluene (99%) were purchased from Sigma-Aldrich. Toluene-d8 (99.5%) was purchased from MERCK and tert-butyl hydrogen peroxide (80%) from Riedel-de Haen. Diethyl ether and THF were dried over Na in the presence of benzophenone. Pentane was distilled

Nucleofugal behavior of a β-shielded α-cyanovinyl carbanion

• Rudolf Knorr and
• Barbara Schmidt

Beilstein J. Org. Chem. 2018, 14, 3018–3024, doi:10.3762/bjoc.14.281

• view of the apparently modest spatial demand of the α-cyano substituent in the adducts of 2Li, it seemed surprising that the following ketones generated no (or no kinetically stable) C=O adducts at rt: t-Bu2C=O, pivalophenone (t-Bu–C(O)–Ph), benzophenone (Ph2C=O) [7], bis(1-methylcyclopropyl)ketone [8

1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation

• A. S. Antonov,
• A. F. Pozharskii,
• P. M. Tolstoy,
• A. Filarowski and
• O. V. Khoroshilova

Beilstein J. Org. Chem. 2018, 14, 2940–2948, doi:10.3762/bjoc.14.273

• sponge moiety: for example, the basicity of benzophenone imine (pKa = 6.82) and even that of cyclohexanone imine (pKa = 9.15) [12] is much lower than that of DMAN (pKa = 12.1) [1][2]. Moreover, as it was already mentioned in the introduction, this is the third known example of a DMAN derivative with a

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• products 27d (Scheme 19) [64]. The N–H imines overcame substrate scope limitation from previous reports with N-aryl and N-alkylimines. Moreover, multiple C–H alkylation was also succeeded with benzophenone imines in high yields with linear selectivity under the mild reaction conditions. In contrast, the

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

• with CH2- and O-bridges in their structure, diazoindandione 1f, diazocyclopentenedione 1g, and as a С–Н donor tetrahydrofuran was employed in the study (Figure 1). To determine the most efficient conditions for this reaction with diazodiketones 1, three sensitizers, acetophenone, benzophenone, and

• used in this study (acetophenone, benzophenone and Michler’s ketone) demonstrate that they show appropriate absorption of the actinic light at the irradiation conditions of diazodiketones 1 (Supporting Information File 1, Table S2). The sensitized photoreactions of diazodiketones 1a–g were carried out

• % (Table 1, entries 1 and 3). The irradiation of tricyclic diazodiketone 1b in the presence of 1 equiv of benzophenone in THF solution led to the formation of hydrazone 2b in a yield of 32% (Table 1, entry 4), whose structure was unambiguously established by X-ray analysis (Figure 2). To increase the

Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• selectively in over 60% yield. However, p-CF3-acetophenone (18%), acetone (14%), cyclohexanone (29%), and benzophenone (25%) were not suitable substrates for C(sp3)–H addition of 1a (figures not shown). We next examined several α-olefins 1 (3 equiv) for allylic C(sp3)–H addition to acetophenone (2a). Not only

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• our group. These were applied to the asymmetric alkylation reaction of benzophenone imine of glycine ester which has become one of the benchmark reactions for examining the performance of new phase-transfer catalysts [36]. Later in 2010, Shirakawa and Shimizu reported the synthesis of novel inherently

• asymmetric alkylation of tert-butyl glycinate benzophenone Schiff base 3 with alkyl halides 4 in a toluene–50% KOH biphasic system (Scheme 1). The corresponding α-alkyl-α-amino acid derivatives 5 were obtained in excellent yields with very low enantioselectivities (up to 9%). This is the first example of

The first Pd-catalyzed Buchwald–Hartwig aminations at C-2 or C-4 in the estrone series

• Ildikó Bacsa,
• Dávid Szemerédi,
• János Wölfling,
• Gyula Schneider,
• Lilla Fekete and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 998–1003, doi:10.3762/bjoc.14.85

• with benzophenone imine and subsequent hydrogenolysis. Keywords: aminoestrones; Buchwald–Hartwig amination; 13α-estrone; functionalization; microwave assisted reactions; Introduction Aminoestrones are of particular interest thanks to their diverse biological applications [1][2][3][4]. There exist

• derivative [17][18]. The C(sp2)–N cross-coupling of the triflate was achieved with benzophenone imine or benzylamine. The removal of the protecting groups resulted in 3-aminoestrone in high yields. Schön et al. developed two convenient protocols for the preparation of 3-aminoestrone using Pd(OAc)2 and Pd2

• -13α-estrone (13). The efficient C(sp2)–N coupling method elaborated above proved to be suitable for the reaction of 2-bromo-3-benzyl ether 2 and benzophenone imine as an amine precursor (Scheme 2). The deprotection was achieved by hydrogenolysis using a Pd/C catalyst. The resulting newly-synthesized 2

2-Iodo-N-isopropyl-5-methoxybenzamide as a highly reactive and environmentally benign catalyst for alcohol oxidation

• Takayuki Yakura,
• Tomoya Fujiwara,
• Akihiro Yamada and
• Hisanori Nambu

Beilstein J. Org. Chem. 2018, 14, 971–978, doi:10.3762/bjoc.14.82

• to benzophenone in the presence of Oxone® (2KHSO5·KHSO4·K2SO4) as a co-oxidant at room temperature. A study on the substituent effect of the benzene ring of N-isopropyl-2-iodobenzamide on the oxidation revealed that its reactivity increased in the following order of substitution: 5-NO2 < 5-CO2Me, 3

• but was lower at 70 °C. However, the reactivity of 13 itself was not so high: the oxidation of benzhydrol (14a) with 0.3 equiv of 13, 2.5 equiv of Oxone®, and 1 equiv of Bu4NHSO4 in MeNO2/H2O (8:3) completed in 12 h at room temperature (25 °C) to produce a 98% yield of benzophenone (15a, Table 1

• benzhydrol (14a) to benzophenone (15a) catalyzed by 13 and 16–25. Oxidation of various alcohols 14b–k with 17.a Supporting Information Supporting Information File 76: Experimental details and the 1H and 13C NMR spectra of the catalysts, the substrates, and the products. Acknowledgments This research was

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• in a dilute solution of toluene, which could be attributed to the strong electron-withdrawing ability and excess conjugation length of fluorenone plane compared with conventional benzophenone acceptor [18]. In addition, low temperature photoluminescence (LTPL) spectra of the materials in toluene at

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone

• Cristina Mozo Mulero,
• Alfonso Sáez,
• Jesús Iniesta and
• Vicente Montiel

Beilstein J. Org. Chem. 2018, 14, 537–546, doi:10.3762/bjoc.14.40

• Cristina Mozo Mulero Alfonso Saez Jesus Iniesta Vicente Montiel Instituto de Electroquímica, Universidad de Alicante, Apartado 99, 03080 Alicante, Spain 10.3762/bjoc.14.40 Abstract The electrocatalytic hydrogenation of benzophenone was performed at room temperature and atmospheric pressure using

• analysis (TGA). Cathodes were prepared using Pd electrocatalytic loadings (LPd) of 0.2 and 0.02 mg cm−2. The anode consisted of hydrogen gas diffusion for the electrooxidation of hydrogen gas, and a 117 Nafion exchange membrane acted as a cationic polymer electrolyte membrane. Benzophenone solution was

• electrochemically hydrogenated in EtOH/water (90/10 v/v) plus 0.1 M H2SO4. Current densities of 10, 15 and 20 mA cm−2 were analysed for the preparative electrochemical hydrogenation of benzophenone and such results led to the highest fractional conversion (XR) of around 30% and a selectivity over 90% for the

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• diphenylsulfone or benzophenone as the acceptors. Here again, the higher twisted molecular structure of T4 was beneficial in terms of ΔEST, color purity and EL performances. Thus, the higher internal torsion of T4 furnished OLEDs with a deeper blue emission (0.154, 0.107) than devices fabricated with T3 (0.174

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• radical. Yadav and co-workers presented a metal-free radical thiol–ene approach, using benzophenone as photoredox catalyst (Scheme 13) [43]. No sacrificial oxidant is required for this reaction as benzophenone is regenerated by hydrogen atom transfer to the anti-Markovnikov radical intermediate. Aliphatic

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• -unsaturated ketones 58 (Scheme 31b). Benzophenone (BP) or anthracene-9,10-dione (AQ) were used as sensitizers under irradiation using a UV lamp at 280 nm. A radical pathway that involves CF3• was established after a negative reaction in the presence of TEMPO (TEMPO–CF3 was detected by GC–MS). An example of