Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• a chiral pocket or environment for enantioselective transformations within the proximity of the acidic proton and phosphoryl oxygen. Additionally, the choice of phosphoric acid diesters also provides a bifunctional catalyst containing both an acidic and basic site (Figure 1). Despite the proven

• ]. Based on the fact that the cis-configuration between the sulfur and the pivalate was absolutely required for enantioselectivity, an interaction between both the sulfur and pivalate carbonyl oxygen with the hydrogen of Hantzsch ester's NH was proposed (Scheme 5). Thus, rather weak interactions might

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• can be controlled. The singlet oxygen quantum yield (ΦΔ) of NI-PTZ is moderate in n-hexane (HEX, ΦΔ = 19%). TADF was observed for the dyads, the biexponential luminescence lifetime are 16.0 ns (99.9%)/14.4 μs (0.1%) for the dyad and 7.2 ns (99.6%)/2.0 μs (0.4%) for the triad. Triplet state was

• lower than those of the amino-NI derivatives (60% to ≈70%) [20]. In order to have a preliminary evaluation of the ISC of the compounds, the singlet oxygen quantum yields (ΦΔ) were studied in several solvents (Table 1 and Table 2). For NI-PTZ, ΦΔ is high in HEX (19%), which is similar to the value

• , indicated by the biexponential fluorescence decay, for instance 16.0 ns (99.9%)/14.4 μs (0.1%). Singlet oxygen photosensitizing experiments showed that the ΦΔ of NI-PTZ is moderate in HEX (ΦΔ = 19%), but that upon oxidation of the PTZ unit in the dyad much larger values were observed for the resulted dyad

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• Artem N. Semakin Ivan S. Golovanov Yulia V. Nelyubina Alexey Yu. Sukhorukov Laboratory of organic and metal-organic nitrogen-oxygen systems, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect, 47, Moscow, 119991, Russian Federation Center for molecular

• , deprotection reactions were performed at low temperatures to prevent degradation of the aminal fragments. Indeed, treatment of Bn-4c with hydrochloric acid at 0 °C resulted in a substitution of one NNH2 unit with the oxygen atom producing product 22, having a hitherto undescribed 4-oxa-1,6,10-triazaadamantane

• -illustrated by Hirshfeld surfaces [41] (Figure 3e and f). The guest molecule (water or methanol) acts as an H-bond acceptor with two axial NH units (distances N···O 2.85–2.93 Å, NHO 166.4–178.0°) and as an H-bond donor for the oxygen atom of the equatorial amide group (distances O···O 2.69–2.78 Å, OHO 163.7

Synthesis of C6-modified mannose 1-phosphates and evaluation of derived sugar nucleotides against GDP-mannose dehydrogenase

• Sanaz Ahmadipour,
• Alice J. C. Wahart,
• Jonathan P. Dolan,
• Laura Beswick,
• Chris S. Hawes,
• Robert A. Field and
• Gavin J. Miller

Beilstein J. Org. Chem. 2022, 18, 1379–1384, doi:10.3762/bjoc.18.142

• diffuse intermolecular C–H···O contacts involving the phosphate and acetyl oxygen atoms. Deprotection of 16 was completed in two steps, first using hydrogenolysis with Adam’s catalyst (PtO2), followed by removal of the acetate protecting groups with Et3N/H2O/MeOH, and furnished the target glycosyl 1

• unknown; b) previously disclosed C6–Me and C6–amido structure-to-function tools for GMD; c) C6-modified GDP-Mans of type 8 and 9, targeted in this work. Structure of 16 with ADPs rendered at the 50% probability level. Acetyl group disorder is omitted for clarity. Atom colour scheme: carbon = black, oxygen

Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• identity can display almost identical biochemical activity. Enzymatic mechanism As monooxygenases, CYPs catalyse the transfer of a single oxygen atom from molecular oxygen to their substrates (Figure 1A). Decades of research on CYPs led to detailed insights into their mechanistic properties based on a

• variety of biochemical, biophysical and computational methods [17][18][19][20][21]. Key for the oxidative chemistry performed by CYPs is a heme prosthetic group that activates molecular oxygen using electrons from an electron donor such as NADPH. A central Fe(III) ion is coordinated by the heme porphyrine

• charge, can then efficiently bind molecular oxygen (step 3), leading to dioxygen adduct D. Transfer of an additional electron from a reducing partner such as cytochrome P450 reductase (step 4) generates peroxo intermediate E, which upon protonation (step 5) gives hydroperoxo intermediate F, also called

Modular synthesis of 2-furyl carbinols from 3-benzyldimethylsilylfurfural platforms relying on oxygen-assisted C–Si bond functionalization

• Sebastien Curpanen,
• Per Reichert,
• Gabriele Lupidi,
• Giovanni Poli,
• Julie Oble and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2022, 18, 1256–1263, doi:10.3762/bjoc.18.131

• activation [19]. Thereby, C3-triorganosilyl-substituted furfurals could be suitable platforms to develop a two-step modular approach to 3-substituted 2-furyl carbinols, entailing nucleophilic addition to the aldehyde function and oxygen-assisted electrophilic substitution of the C–Si bond (Scheme 1). Results

• ). With the 3-silylated 2-furyl carbinol substrates at hand, we then considered C–Si bond activation strategies relying on the assistance of the oxygen atom to promote electrophilic substitution reactions with carbon electrophiles. C3–Si bond functionalization through intramolecular activation by

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• -workers found that ball milling of the cross-linked polyacrylate polymer 1 could trigger the release of singlet oxygen from the anthracene–endoperoxide mechanophores (Scheme 1a) [27]. To support the claim that the generation of 1O2 occurred mechanically rather than thermally due to local heat formation by

Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide

• Blaine G. Fiss,
• Georgia Douglas,
• Michael Ferguson,
• Jorge Becerra,
• Jesus Valdez,
• Trong-On Do,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2022, 18, 1203–1209, doi:10.3762/bjoc.18.125

• ; Introduction The development of heteroatom-doped graphitic carbon nitrides (g-CN) has been a rapidly growing area of research since their first report towards water splitting in 2009 [1]. Since that time, the addition of elements such as boron [2], phosphorus [3][4][5], sulfur and oxygen [6] have shown to help

• the pure reaction product. The variations may be ascribed to the oxygen content found by XPS (Figure 2) or that the mechanochemically synthesized material exists in a different spatial configuration to those previously predicted [46][47]. Thermal stability Prior to annealing, g-h-PCN was found to show

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• -p3C aggregates. Thus, a judicious choice of D–A molecular architecture is necessary to tune the solid- or aggregated-state optical properties for triplet harvesting. Fluorescence switching The lone-pair electrons of heteroatoms, such as oxygen and nitrogen, are susceptible to acidic protons [22]. BPy

• medium was obtained (Figure S6a in Supporting Information File 1). The absorption spectra upon addition of TEA again matched with the absorption spectra in toluene (Figure S6a, Supporting Information File 1). Further, TDDFT calculations for a protonated pyridinyl nitrogen atom (N–H) and carbonyl oxygen

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

• Mana Kitano,
• Tsuyoshi Saitoh,
• Shigeru Nishiyama,
• Yasuaki Einaga and
• Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

• hydroperoxide/dicumyl peroxide/phenol from cumene, acetophenone from ethylbenzene, and others. Generally, molecular oxygen has been utilized in the straightforward oxidation of aromatic alkyls. However, since molecular oxygen is highly stable, activation of the molecular oxygen itself is necessary, which

• in 21% yield. Therefore, it is indicated that the reaction intermediate is the cumyl cation. Second, we carried out the electrolysis of 1 in MeCN–H2O to confirm whether the oxygen source is dissolved oxygen or residual water. When dehydrated MeCN was used, 3 was obtained as the main product (Table 2

• , entry 2). On the other hand, the isolated yield of 3 was decreased by the addition of H2O (Table 2, entries 3 and 4). This is probably because the addition of H2O promoted the generation of hydroxyl radicals, and a decomposition reaction became dominant. These results indicated that the oxygen source is

Radical cation Diels–Alder reactions of arylidene cycloalkanes

• Kaii Nakayama,
• Hidehiro Kamiya and
• Yohei Okada

Beilstein J. Org. Chem. 2022, 18, 1100–1106, doi:10.3762/bjoc.18.112

• toward atmosphere; both oxygen and argon had a negative impact (Table 1, entries 7 and 8). In the electrochemical approach, potentiostatic conditions gave better results than galvanostatic conditions and more importantly, it was found that the reaction was completed within 0.5 F/mol (Table 1, entries 9

Synthesis of N-phenyl- and N-thiazolyl-1H-indazoles by copper-catalyzed intramolecular N-arylation of ortho-chlorinated arylhydrazones

• Yara Cristina Marchioro Barbosa,
• Guilherme Caneppele Paveglio,
• Claudio Martin Pereira de Pereira,
• Sidnei Moura,
• Cristiane Storck Schwalm,
• Gleison Antonio Casagrande and
• Lucas Pizzuti

Beilstein J. Org. Chem. 2022, 18, 1079–1087, doi:10.3762/bjoc.18.110

• cycloaddition reaction of α-diazomethylphosphonates with o-(trimethylsilyl)phenyl triflate in the presence of CsF [13], Cu2+-mediated N−N bond formation from ketimines in the presence of oxygen [14], Pd2+-mediated oxidative benzannulation from pyrazoles and internal alkynes [15], Pd-catalyzed Aza–Nenitzescu

Facile and diastereoselective arylation of the privileged 1,4-dihydroisoquinolin-3(2H)-one scaffold

• Dmitry Dar’in,
• Grigory Kantin,
• Alexander Bunev and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2022, 18, 1070–1078, doi:10.3762/bjoc.18.109

• 16 was obtained and its structure was confirmed by single-crystal X-ray analysis. Presumably, the formation of ester 16 can be justified by the trapping of the carbocation intermediate 17 (vide infra) by the formamide carbonyl oxygen atom followed by hydrolysis of the iminium moiety (Scheme 4

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

• Yi-Lun Li,
• Zhaojiang Shi,
• Tao Shen and
• Ke-Yin Ye

Beilstein J. Org. Chem. 2022, 18, 1026–1031, doi:10.3762/bjoc.18.103

• Supporting Information File 1). Therefore, the oxygen source of the newly formed carbonyl moiety may originate directly from the vinyl acetate. This conclusion is also consistent with the fact that even in the absence of water, the desired α-azidoketone was still obtained. Under the optimal conditions, the

• water to form the desired product E. According to our 18O labeling experiment, the oxygen source of the newly installed carbonyl group probably originates from the vinyl acetate, not from H2O. Conclusion In summary, we have developed an environmentally friendly and efficient electrochemical oxyazidation

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• imidazolone 1b (<5%), probably due to the reaction with adventitious oxygen, was observed from the NMR spectrum. It should be underlined that in these electrolyzes BMImBF4 acts as both electroactive species and supporting electrolyte, and although the cathodic reduction of the imidazolium cation is a

• molecular oxygen, or electrochemically generated superoxide (cathodic reduction of O2), which oxidize the Breslow intermediate [30][39]. In fact, the presence of some reactive oxygen species in the reaction environment was previously demonstrated by the formation of compound 1b (see Table 1). IL Recycling

Electrochemical and spectroscopic properties of twisted dibenzo[g,p]chrysene derivatives

• Tomoya Imai,
• Ryuhei Akasaka,
• Naruhiro Yoshida,
• Toru Amaya and
• Tetsuo Iwasawa

Beilstein J. Org. Chem. 2022, 18, 963–971, doi:10.3762/bjoc.18.96

• the effect of conjugation for the orbital of an oxygen atom as shown in the schematic drawing in Figure 3. When the conformation of the MeO group is almost parallel to the benzene ring, the strong orbital interaction between the orbitals on the oxygen and adjacent carbon atoms is possible in HOMO (the

• orbital drawings are also shown in Figure S2 in Supporting Information File 1). In this case, the mesomeric effect of an oxygen atom is dominant. On the other hand, when the conformation of the MeO group is almost perpendicular to the benzene ring, the interaction between orbitals on the oxygen and

• adjacent carbon atoms becomes weak in the case of HOMO. In this case, the inductive effect of an oxygen atom can be dominant. Thus, the substituents at the Z position allow the MeO group to be oriented perpendicular to the benzene ring, which results in the lowering of both the HOMO and LUMO (Figure 3). In

Synthetic strategies for the preparation of γ-phostams: 1,2-azaphospholidine 2-oxides and 1,2-azaphospholine 2-oxides

• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 889–915, doi:10.3762/bjoc.18.90

• ]. In the same year, they also realized the synthesis of 2-phenyl-1,3-dihydrobenzo[d][1,2]azaphosphole 2-oxide (55) in 75% yield by heating at 190–200 °C and in 47% yield by DCC condensation of compound 54 – the oxygen analogue of 2-aminobenzyl(phenyl)dithiophosphinic acid 58. The cyclodehydration

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

• Sadanobu Iwase,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

• ; (phenylthio)difluoromethyl radical; Introduction Organofluorine compounds containing a difluoromethylene group have been of much interest from biological aspects since the difluoromethylene group is isopolar and isosteric with an ether oxygen [1][2]. Particularly, organic molecules bearing a (arylthio

Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry

• Koji Kubota,
• Emiru Baba,
• Tamae Seo,
• Tatsuo Ishiyama and
• Hajime Ito

Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86

• . Additionally, to avoid the deterioration of reactivity due to moisture and oxygen, conventional protocols require synthesis techniques that involve the use of high-vacuum Schlenk lines and/or glove boxes, which are costly and require special training to handle. Thus, the development of an operationally simple

First series of N-alkylamino peptoid homooligomers: solution phase synthesis and conformational investigation

• Maxime Pypec,
• Laurent Jouffret,
• Claude Taillefumier and
• Olivier Roy

Beilstein J. Org. Chem. 2022, 18, 845–854, doi:10.3762/bjoc.18.85

• second group of molecules (conformation B). In the crystal lattice, each molecule establishes four intermolecular CO···HN hydrogen bonds. Only the inter-residue carbonyl (oxygen atom labeled O2, Figure 3C) participates in this network, making two hydrogen bonds with two different molecules and different

Synthesis and HDAC inhibitory activity of pyrimidine-based hydroxamic acids

• Virginija Jakubkiene,
• Gabrielius Ernis Valiulis,
• Markus Schweipert,
• Asta Zubriene,
• Daumantas Matulis,
• Franz-Josef Meyer-Almes and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 837–844, doi:10.3762/bjoc.18.84

• the most successful with an overall reaction yield as high as 82% and a ratio of O- to N-isomers 24a to 24b as high as 3.3:1 (Table 1, entry 7). As expected, the polar aprotic solvent dimethylformamide promoted the reaction of the electrophile with the more negatively charged oxygen atom by well

Synthesis of bis-spirocyclic derivatives of 3-azabicyclo[3.1.0]hexane via cyclopropene cycloadditions to the stable azomethine ylide derived from Ruhemann's purple

• Alexander S. Filatov,
• Olesya V. Khoroshilova,
• Anna G. Larina,
• Vitali M. Boitsov and
• Alexander V. Stepakov

Beilstein J. Org. Chem. 2022, 18, 769–780, doi:10.3762/bjoc.18.77

• Ruhemann's purple with hydrochloric acid, three tautomers 1, 1', and 1'' may be theoretically formed, i.e., protonation could occur at the nitrogen atom, the oxygen atom or the carbon atom, respectively (Scheme 7). According to literature data [27], the nitrogen atom of Ruhemann's purple is considered to be

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• ) with molecular oxygen at elevated temperatures providing (+)-nootkatone (8) in 10% yield (Scheme 2). In this setup, neat (+)-valencene (7) is mixed with a stream of oxygen resulting in the formation of a segmented gas–liquid flow. In segmented flow a higher surface-to-volume ratio is achieved and

• resembling that of hawthorn or a harsh orange-blossom type“. Acetophenone appears in vintage Geoffrey Beene: Grey Flannel at 0.14%, and Shiseido: Zen and Gap: Om at approx. 0.014%. In 2013, Roberge, Kappe, and co-workers investigated the C–H oxidation of ethylbenzene (37) to acetophenone with oxygen as an

• state of the decatungstate anion generates carbon-centered radical 48 which is trapped in a segmented flow with molecular oxygen provided by a mass flow controller. Peroxide 49 is formed as intermediate which further reacts to phthalide (50) in 71% yield. This method efficiently utilizes the advantages

Identification of the new prenyltransferase Ubi-297 from marine bacteria and elucidation of its substrate specificity

• Jamshid Amiri Moghaddam,
• Huijuan Guo,
• Karsten Willing,
• Thomas Wichard and
• Christine Beemelmanns

Beilstein J. Org. Chem. 2022, 18, 722–731, doi:10.3762/bjoc.18.72

• spectrometer equipped with a Bruker Cryoplatform with chemical shifts given in ppm (δ). Prenylated aromatic metabolites are involved in cellular processes like cell respiration (coenzyme Q10), cell growth and survival (menaquinone MK-4), photosynthesis (chlorophyll a), oxygen reduction (heme O), and

Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• endoperoxide-containing natural products, numerous synthetic analyses and biosynthesis of endoperoxide compounds have been reported [18][19][20][21]. In some cases; e.g., in the biosynthesis of artemisinin and ergosterol peroxides, a reactive oxygen species (ROS) such as singlet oxygen, which is generated by

• ], which share ≈60% amino acid identity [33]. Both isoforms catalyze the incorporation of two oxygen atoms into arachidonic acid (AA) to form an endoperoxide between C9 and C11 and a peroxide at C15 to generate prostaglandin G2 (PGG2) (Scheme 1) [24][34]. Subsequently, the 15-hydroperoxide in PGG2 is

• through the two-electron reduction of PGG2, to form a tyrosyl radical in the active site of the cyclooxygenase-site (Scheme 2) [24][34][63]. The tyrosyl radical then abstracts a C13-pro-S hydrogen atom from AA to produce the arachidonoyl radical, which is delocalized over C11 to C15. An oxygen molecule