Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• . The formed N-alkoxylated intermediate is converted into the desired product 39.2 after oxidation and releases another alkoxy radical at the same time. The measured quantum yield (Φ = 4.4) indicates that a chain mechanism is operative. Recently, the same group applied a similar organophotocatalytic

• used as initators for the synthesis of highly functionalized benzo[b]phosphole oxides from arylphosphine oxide and alkynes [162]. Alkyl hydroperoxides can act as oxidants in photocatalytic cycles, furnishing the desired alkoxy radicals. Several organic dyes have been exploited in these processes

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

• Dong Cai,
• ZhiHua Zhang,
• Yufan Meng,
• KaiLi Zhu,
• LiYi Chen,
• ChangXiang Yu,
• ChangWei Yu,
• ZiYi Fu,
• DianShen Yang and
• YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

• instance, the hydroxy group can be converted into an oxime, acyloxyimino, alkoxyimino, alkoxy and 3-oxo group [9]. As a proteasome inhibitor, compound a suppresses the chymotrypsin-like activity of the proteasome in MT4 cells with an IC50 of 0.22 μM, nearly 100-fold more potent than 18β-glycyrrhetinic acid

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• Yumi Yakiyama Shota Hishikawa Hidehiro Sakurai Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan 10.3762/bjoc.16.66 Abstract Buckybowls bearing a C70 fragment having two alkoxy groups were synthesized and their structural

• the external aromatic ring of the indenopyrene using various types of o-bromo arylaldehydes. Related to our study on buckybowl-containing liquid crystals [19], we planned to introduce alkoxy groups on the 1 framework. Here, we report the synthesis and characterization of dimethoxy derivative 5a and

• succeeded in synthesizing three different alkoxy-substituted C70-fragment buckybowls 5a–c. In particular, 5c was not an intended molecule, but was formed unexpectedly through the rearrangement through the Pd-catalyzed C–H bond activation reaction. The X-ray crystal structure analysis of 5a–c clearly

Cascade trifluoromethylthiolation and cyclization of N-[(3-aryl)propioloyl]indoles

• Ming-Xi Bi,
• Shuai Liu,
• Yangen Huang,
• Xiu-Hua Xu and
• Feng-Ling Qing

Beilstein J. Org. Chem. 2020, 16, 657–662, doi:10.3762/bjoc.16.62

• effect of the substitution on the indole ring. Both electron-donating and withdrawing groups at different positions of the indole ring produced the bis(trifluoromethylthiolated) products 2a–o in moderate to good yields. A wide range of functionalities such as alkyl, alkoxy, nitro, nitrile, ester

Direct borylation of terrylene and quaterrylene

• Haruka Kano,
• Keiji Uehara,
• Kyohei Matsuo,
• Hironobu Hayashi,
• Hiroko Yamada and
• Naoki Aratani

Beilstein J. Org. Chem. 2020, 16, 621–627, doi:10.3762/bjoc.16.58

• . Larger oligorylenes have not been synthesized without the use of solubilizing groups along the rylene backbone. For instance, bay-bridging perylenes with long alkyl chains [12][13][14][15] and bay-alkoxy-substitution [16][17][18] enable us to prepare longer rylenes (Figure 1c and 1d). However, tying the

• bay regions with carbon or nitrogen atoms causes bowing of the oligorylene backbone without disrupting the planarity of the aromatic backbone to give a flat banana-shaped molecule [15]. On the other hand, the bay-alkoxy-substitution is estimated to twist the core, which changes the original

• -bridging oligorylenes, d) bay-alkoxy oligorylenes, and e) tetra-tert-butyl oligorylenes. (Top) Single crystal X-ray structure of TB4. The thermal ellipsoids are scaled at 50% probability. (Bottom) Packing diagram of TB4. The solvent molecules are omitted for clarity. UV–vis absorption and fluorescence

Preparation and in situ use of unstable N-alkyl α-diazo-γ-butyrolactams in Rh^II-catalyzed X–H insertion reactions

• Maria Eremeyeva,
• Daniil Zhukovsky,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2020, 16, 607–610, doi:10.3762/bjoc.16.55

• compounds, namely, α-diazo-γ-butyrolactams [1]. In particular, N-aryl-α-diazo-γ-butyrolactams 1 were efficiently transformed into pyrrolinones 2 upon the treatment with AgOTf (1 mol %) and into α-alkoxy derivatives 3 via Rh2(OAc)4-catalyzed O–H insertion reactions with various alcohols. In contrast, N-alkyl

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• alkyl and alkoxy substituents at the 3, 6, 13, and 16-positions was achieved based on the ruthenium-catalyzed coupling reactions of anthraquinone derivatives with arylboronates via C–H and C–O bond cleavage. The reaction sequence involving the arylation, carbonyl methylenation, and oxidative cyclization

• class of tetrabenzo[a,d,j,m]coronene derivatives having alkyl and alkoxy-substituents at the 3, 6, 13, and 16-positions was achieved based on a ruthenium-catalyzed coupling reaction of anthraquinone derivatives with arylboronates via a C–H or/and C–O bond cleavage. The reaction sequence involving the

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• catalyst (Scheme 2). This one-pot construction of the benzo[b]phosphole core ensured the preferential phosphole ring closure in proximity of the alkoxy group of the arylzinc reagent 1 (regioselectivity of ≈3:1), presumably due to a secondary interaction between the MOM group and the cobalt catalyst during

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• the presence of the acid, it is protonated and collapses into the corresponding alkoxy radical. This radical carries out a 1,5-HAT to generate a carbon-centered radical. Finally, this radical recombines with the α-amino radical generated from the above-mentioned pathway. 2.3 Oxidation reactions In

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• and/or alkoxy derivatives 29–31. Selectively varying the molar ratio of the silylphosphine nucleophile and the starting reagent 25 resulted in the corresponding bis- and tris(diphenylphosphine)triazine motifs 27 and 28. A subsequent nucleophilic substitution reaction of 27 gave compounds 32 and 33

Allylic cross-coupling using aromatic aldehydes as α-alkoxyalkyl anions

• Akihiro Yuasa,
• Kazunori Nagao and
• Hirohisa Ohmiya

Beilstein J. Org. Chem. 2020, 16, 185–189, doi:10.3762/bjoc.16.21

• -catalyzed allylic substitution. Keywords: aldehyde; copper; copper catalysis; cross-coupling; palladium; synthetic method; Introduction α-Alkoxy-substituted carbanions (α-alkoxyalkyl anions) are useful C(sp3) nucleophiles for the construction of alcohol units found in a majority of pharmaceuticals

The reaction of arylmethyl isocyanides and arylmethylamines with xanthate esters: a facile and unexpected synthesis of carbamothioates

• Narasimhamurthy Rajeev,
• Toreshettahally R. Swaroop,
• Ahmad I. Alrawashdeh,
• Shofiur Rahman,
• Abdullah Alodhayb,
• Seegehalli M. Anil,
• Kuppalli R. Kiran,
• Chandra,
• Paris E. Georghiou,
• Kanchugarakoppal S. Rangappa and
• Maralinganadoddi P. Sadashiva

Beilstein J. Org. Chem. 2020, 16, 159–167, doi:10.3762/bjoc.16.18

• reported the synthesis of thiazoles from xanthate esters [31]. In continuation of this ongoing work, we planned to synthesize 5-alkoxy-4-arylthiazoles 3 by the sodium hydride/DMF-mediated reaction of arylmethyl isocyanides 2 with S-alkyl xanthate esters 1 or O-aryl/O-alkyl dithiocarbonates. Unexpectedly

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• et al. investigated on the liquid crystalline behaviour of some bis(phenyl-1,3,4-oxadiazolyl)benzene derivatives with varied number and length of terminal alkoxy chains [32]. The authors established that the mesogenicity is strongly enhanced in materials with four long terminal alkoxy substituents

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

• excellent yields, with the hydroperoxide functional group acting as a precursor of an alkoxy radical to control site-selective carbon-centered radical formation. Allylic fluorination: In 2011, the group of Nguyen [92] developed the nucleophilic fluorination of allylic trichloroacetimidates, as shown in

Nanopatterns of arylene–alkynylene squares on graphite: self-sorting and intercalation

• Tristan J. Keller,
• Joshua Bahr,
• Kristin Gratzfeld,
• Nina Schönfelder,
• Marcin A. Majewski,
• Marcin Stępień,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2019, 15, 1848–1855, doi:10.3762/bjoc.15.180

• graphite and 1,2,4-trichlorobenzene. Self-sorting leads to the intermolecular interdigitation of alkoxy side chains of identical length. Voids inside and between the squares are occupied by intercalated solvent molecules, which numbers depend on the sizes and shapes of the nanopores. In addition, planar

• with different numbers of sides [18], that are scalable to some extent [19]. The long alkoxy side chains mediate sufficient compound solubility and compound adsorption on highly oriented pyrolytic graphite (HOPG) that acts as a template [20][21], and determine the intermolecular interaction [22][23][24

• ]. The patterns formed by the polygons, especially the bigons, triangles, squares, and hexagons as well as molecular spoked wheels, are alike if the dithiophene corner pieces are exchanged by other corners, or if the side length is altered [19]. However, in all these cases the alkyl/alkoxy side chains at

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• that differs from the common macrocycles is the planar chirality resulting from the different orientations of the alkoxy substituents on the rims. Theoretically, eight conformers can be formed including diastereomeric ones: (Sp,Sp,Sp,Sp,Sp), (Rp,Sp,Sp,Sp,Sp), (Rp,Rp,Sp,Sp,Sp), (Rp,Sp,Rp,Sp,Sp) and

• their antipodal enantiomers: (Rp,Rp,Rp,Rp,Rp), (Sp,Rp,Rp,Rp,Rp), (Sp,Sp,Rp,Rp,Rp), (Sp,Rp,Sp,Rp,Rp). Among them, the enantiomeric per-Sp (Sp,Sp,Sp,Sp,Sp) and per-Rp (Rp,Rp,Rp,Rp,Rp) conformers (abbreviated as Sp and Rp, respectively), in which all of the alkoxy substituents at both rims are oriented in

Synthesis of dipolar molecular rotors as linkers for metal-organic frameworks

• Sebastian Hamer,
• Fynn Röhricht,
• Marius Jakoby,
• Ian A. Howard,
• Xianghui Zhang,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1331–1338, doi:10.3762/bjoc.15.132

• groups are known to exhibit the highest electron-withdrawing effect among the uncharged small functional groups [54]. As electron-donating substitutents, amino groups exhibit the strongest effects, especially if tris-alkyl substituted. However, we chose alkoxy substituents for our design, because

• phenylenediamine (1,2-diaminobenzene) units are strongly coordinating ligands which interfere with MOF formation. Moreover, alkoxy substituents provide several advantages in synthesis. While methoxy substituents are known and common donors, calculations showed that bridged alkoxy substituents such as the

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

• at the para-position of the p-nitrophenyl group in 2a. As observed in the OP uncaging reaction at 365 nm, the efficiency of the TP-induced TEMPO uncaging reaction of 2a was almost three times higher than that of 2b in benzene. This is attributed to the substituent effect of the meta-alkoxy group on

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• Marwan Simaan Ilan Marek The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 32000, Israel 10.3762/bjoc.15.71 Abstract The diastereoselective carbocupration reaction of alkoxy-functionalized cyclopropene derivatives

• group [90][91][92]. Conclusion In conclusion, we have successfully merged the regio- and diastereoselective carbocupration reaction of alkoxy-functionalized cyclopropenes with electrophilic oxidation of the resulting cyclopropylcopper species to afford 2,2,3,3-polysubstituted cyclopropanol derivatives

Tuning the stability of alkoxyisopropyl protection groups

• Zehong Liang,
• Henna Koivikko,
• Mikko Oivanen and
• Petri Heinonen

Beilstein J. Org. Chem. 2019, 15, 746–751, doi:10.3762/bjoc.15.70

• chromatography without degradation. The compatibility of these protecting groups in parallel use with benzoyl and silyl groups was verified. The stabilities of the different alkoxy acetal protecting groups were compared by following the kinetics of their hydrolysis at 25.0 °C in buffered solutions through an

• HPLC method. In the pH range 4.94 to 6.82 the hydrolysis reactions are of first order in the hydronium ion. The rate of hydrolysis correlates with the electron-donating or electron-withdrawing ability of the corresponding alkoxy group. The studied 2-alkoxypropan-2-yl groups and the relative rate

• [7]. We realized that the lability of the acetal group can be easily steered by varying the alkoxy group, while preserving other beneficial properties of the protecting groups. On the other hand, structural modifications can also affect the lipophilicity of the protected compounds. The present study

The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• reaction is very broad and almost all types of nitriles and carboxylic acids have successfully been used. The alkoxy group introduced via the allene component is also variable and hence the subsequent transformation of this substituent into a hydroxy group can be performed under different conditions

• -labile alkoxy substituents such as a 2-(trimethylsilyl)ethoxy group are required for the conversion of β-ketoenamides into 5-acetyl-substituted oxazoles OX, again compounds with high potential for subsequent functional group transformations. For acid labile β-ketoenamides bearing bulky substituents the

• carboxylic acids with tertiary centers are possible candidates for the route to β-ketoenamides. The last example shown in Scheme 5 demonstrates that allenes with chiral alkoxy substituents are also suitable starting materials in the three-component reaction. We did not study lithiated carbohydrate-derived

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• importance of this procedure is reflected in the multistep reactions applied for the preparation of some bioactive imidazole derivatives [22][23]. However, the preparation of imidazole-2-thiones with N-alkoxy groups, starting with the corresponding 2-unsubstituted imidazole 3-oxides, has not yet been

• diverse 1-(adamantyloxy)imidazole 3-oxides as well as to 1,3-dialkoxyimidazolium salts, which are attractive substrates for syntheses of other imidazole derivatives, including a new group of 1-alkoxy and 1,3-dialkoxyimidazol-2-ylidenes. In all described cases, it is of interest to probe the influence of

• the alkoxy residues on the stability and reactivity of the hitherto unknown nucleophilic carbenes bearing this groups at N(1) and/or N(3) atoms. In addition, it is worth mentioning that 1,3-dibenzyl-4,5-dimethylimidazolium chloride as well as its 2-methyl-substituted analogue are well known imidazole

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

• Raines reported examples of RCM, CM and ROMP in heterogeneous conditions with hydrophobic catalysts [21][33]. Blechert prepared alkoxy- and cyano-substituted catalysts 19 and 20 from G-II (Scheme 5) [34], while Raines and co-workers employed the conventional catalysts G-II and HG-II [35]. Blechert and

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• Dowex 50WX8 resin. According to the patent publication of Livingston et al. [60], the chloridate 32 may be reacted not only with water but also with alcohols, such as isopropanol, ethanol, propanol, methanol, butanol, to result in the mono-substitution of a chlorine atom in 32 with corresponding alkoxy

• group and – after quenching with water – to give NMN analogues with one alkoxy group at the phosphorus atom. The resulting compounds were purified by column chromatography on an aminopropyl-modified silica gel Quadrasil AP column to yield the pure NMN analogues in low to moderate yields (8–40%). The