Synthesis of tryptophan-dehydrobutyrine diketopiperazine and biological activity of hangtaimycin and its co-metabolites

• Houchao Xu,
• Anne Wochele,
• Minghe Luo,
• Gregor Schnakenburg,
• Yuhui Sun,
• Heike Brötz-Oesterhelt and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1159–1165, doi:10.3762/bjoc.18.120

• material that was obtained as a viscous oil, failed. The X-ray crystallographic analysis of (rac)-4 showed an interesting dimer interaction of its enantiomers through hydrogen bridges between the amide (NH-CO) groups (Figure 2, for crystallographic parameters cf. Supporting Information File 1, Table S1

• ), that may support its easy crystallisation in comparison to enantiomerically enriched 4. Note that the dimer between the two enantiomers of 4 is achiral which allows for a regular packing of (rac)-4 in the crystal. In contrast, a hypothetical similar interaction between two molecules of the same

• enantiomer can only lead to a chiral dimer that, if formed at all, may crystallise less efficiently. Bioactivity testing Previous reports have mentioned that TDD (4) exhibits no antibacterial activity, without providing information about the test organisms used [9]. For this reason, and because of the above

A Streptomyces P450 enzyme dimerizes isoflavones from plants

• Run-Zhou Liu,
• Shanchong Chen and
• Lihan Zhang

Beilstein J. Org. Chem. 2022, 18, 1107–1115, doi:10.3762/bjoc.18.113

• challenging and often requires prefunctionalization of the substrate monomers, costly metal ligands, or tedious protection–deprotection steps [6][7][8][9]. With the advance of biosynthetic studies on natural products, a number of enzyme classes that are responsible for the dimer formation have been identified

• contain isoflavones. These cultures did not produce 1–3, but daidzein (4) supplementation in ISP-2 liquid medium restored the production of 1–3, suggesting that S. cattleya utilizes exogenous isoflavone to form the dimer products 1–3 (Figure 2a). A comparison of the 1H NMR spectra of 1 and 4 (Tables S3

• dimer with a rare 5,8’’ biaryl coupling skeleton. Likewise, C-8’’ was assigned as one of the coupling sites of 2. Three B-ring protons, H-2’ (δH 7.38, d), H-5’ (δH 7.02, d), and H-6’ (δH 7.48, dd), suggested that C-3’ was another coupling site. Thus, the structure of 2 was established as a 3’,8

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

• solid state by X-ray crystallography (dimer 2), and implicit solvent QM geometry optimizations. N-(Methylamino)peptoids were found to preferentially adopt trans amide bonds with the side chain N–H bonds oriented approximately perpendicular to the amide plane. This orientation is conducive to local

• antiparallel arrangement of mirror image molecules held together via two hydrogen bonds in the crystal lattice of dimer 2. Keywords: cis/trans isomerism; peptoid; structure; trans-inducing side chain; Introduction The term “peptoids” refers to the family of artificial oligo(poly)mers consisting of N

• to the mixed anhydride activating method using isobutyl chloroformate (IBCF) in the presence of N-methylmorpholine (NMM) at 0 °C in DMF for 10 min, followed by the addition of hydrazine 1a [43][44]. The best results were obtained with two equivalents of preformed mixed anhydride, pure dimer 2d being

Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold

• Anastasia Vepreva,
• Alexander S. Bunev,
• Andrey Yu. Kudinov,
• Grigory Kantin,
• Mikhail Krasavin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55

• of DAS 1a in dichloromethane in the presence of Rh2(esp)2 (0.1 mol %) led to the formation of a mixture of the major product ‒ dimer 2a, and minor indene 3a (Table 1, entry 1). The target dimer was isolated in 74% yield as a single diastereomer. Its structure was reliably confirmed by X-ray analysis

• of DAS 1i containing a trifluoromethyl group in the arylidene ring (Table 1, entry 9). In the latter case, the negative effect of the presence of the electron-withdrawing group also manifested itself in a significant decrease in the yield of the target dimer 2 due to the formation of unidentified

• byproducts. For the 3-methoxy-substituted DAS 1n, the main reaction outcome was the unimolecular cyclization, leading to a mixture of regioisomeric indenes (Table 1, entry 14) while the target dimer 2n was obtained in low (12%) yield. A similar result was obtained earlier in the study of DAS in the reaction

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• by a dimer can be described as an SN3 process and, presumably, attack by a trimer would be SN4 and so forth. There is nothing wrong with either of these formulations provided the processes are suitably defined. Such a definition and explanation are given in Scheme 1 of the 2009 paper [69] by Bentley

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• %, with Commission Internationale de l’Éclairage coordinate of (0.22, 0.47), at 1 mA cm−2. Keywords: blue emitters; dimer; indolocarbazole; orientation; outcoupling effect; solution-processed OLEDs; TADF emitters; triazine; Introduction Organic thermally activated delayed fluorescence (TADF) materials

• light outcoupling in the device. Results and Discussion Synthesis The oxidative coupling conditions for the synthesis of carbazole dimers were initially applied to access the dimer of ICzTRZ [25][26]. Treating ICzTRZ with FeCl3 in dichloromethane (DCM) at room temperature for 12 hours did not lead to

Synthetic strategies toward 1,3-oxathiolane nucleoside analogues

• Umesh P. Aher,
• Dhananjai Srivastava,
• Girij P. Singh and
• Jayashree B. S

Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182

• toluene solvent. The synthesis and antiviral evaluation of 4'-(hydroxymethyl)oxathiolane nucleosides was reported by Chao and Nair [52]. The synthetic approach used 1,3-dihydroxyacetone dimer 3l (Scheme 14). This dimer, upon acetylation using acetic anhydride in pyridine, produced compound 47. Further

• -oxathiolane intermediates 65 and 66 could be controlled well (Scheme 22). The glycolaldehyde dimer 64 and 1,4-dithiane-2,5-diol (3q) were reacted in the presence of TEA and the acyl donor phenyl acetate. The presence of CAL-B allowed the formation of the intermediate 66 and ultimately the corresponding

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• alkyne (Scheme 18). Under visible-light irradiation, disulfides are easy transformed to thiyl radicals via the homolytic cleavage of the S–S bond [79]. In 2020, Anandhan and co-workers [80] explored the C(sp)–S coupling of terminal alkynes with 2-aminothiophenol dimer 38 as a radical precursor. Under

• photoexcitation the CuI acetylide A undergoes a SET process to form the CuII phenylacetylide species B and a superoxide radical anion. In parallel, under irradiation the homolytic S–S-bond cleavage in 2-aminothiophenol dimer 38 forms thiol radicals 40. The nucleophilic addition of the amino group in radical 40 to

Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines

• Matthew J. Fleming and
• David M. Hodgson

Beilstein J. Org. Chem. 2021, 17, 2385–2389, doi:10.3762/bjoc.17.155

• hexane (69%, E/Z = 62:38) and the amount of dimer 24 curtailed (8%) by reducing the amount of LTMP from 2 to 1.2 equiv. The viability of a benzyl ether (Scheme 10) in the carbenoid eliminative cross-coupling offered a straightforward way to probe any effect of the size of the leaving group on

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• Mn and PDI were 2900 Da and 1.22, respectively. The aminoazulene dimer 29 was also synthesized (Scheme 7B) in this study as a reference compound. When compared to the dimeric aminoazulene 29 (481 nm) and 2-aminoazulene (24, 394 nm), the polyaminoazulene 31 exhibited a far red-shifted broad absorption

• band spanning 400–800 nm in NMP solution with a maximum at 591 nm. Accordingly, the optical energy gap for the polymer 31 was the lowest (1.65 eV) in comparison to dimer 29 (2.15 eV) and monomer, 2-aminoazulene (24, 3.15 eV) emphasizing the advantage associated with inducing a 2,6-connectivity along

• forms of monomer 24, dimer 29, and polyazulene 31 were further red-shifted and their respective energy gaps were also reduced compared to their neutral forms. The oxidation potential for the neutral (−0.23 V) and protonated forms of polyaminoazulene 31 (0.70 V) was significantly different unlike the

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• -trifluoroacetylation of peracetylated chitooligomers, could efficiently generate 1,2-(2-trifluoromethyloxazoline) donors. These reactive compounds were employed to construct different length COS, from dimer to hexamer [236]. Synthetic COS were prepared following chemical or enzymatic polymerization, albeit with poor

• used in a [2 + 2] glycosylation, affording the tetramer 74 with an alternated N-acetyl pattern (Scheme 11A) [257]. Partially N-acetylated COS dimer and tetramer were obtained exploiting the orthogonality of the azide and N-Troc groups [258]. β-Selectivity during the glycosylation with the C-2 azido

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• archetypal cyclophane, with a strong interaction between the two aromatic rings, but it is readily available, being a ‘dimer’ for the polymer parylene [6][7]. Over the last twenty years, there has been a resurgence in interest in this compound as a scaffold for the synthesis of asymmetric catalysts, energy

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

Structural effects of meso-halogenation on porphyrins

• Keith J. Flanagan,
• Maximilian Paradiz Dominguez,
• Zoi Melissari,
• Hans-Georg Eckhardt,
• René M. Williams,
• Dáire Gibbons,
• Caroline Prior,
• Gemma M. Locke,
• Alina Meindl,
• Aoife A. Ryan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2021, 17, 1149–1170, doi:10.3762/bjoc.17.88

• porphyrin dimer with a di-halogeno-substitution. Interestingly, this structure despite the extended dual-core and tilt of the porphyrin rings behaves quite like a 5,15-di-halo-substituted porphyrin. The bromine atoms are seen to interact with the tert-butyl and pyrrole hydrogen atoms in a head-to-tail

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• synthesize the nucleoside dimer phosphoramidite with the appropriate amide linkage, which can then be introduced into the strand by solid-phase synthesis. These dimers are synthesized by using an amide coupling reagent to condense a 3'-carboxylic acid nucleoside with a 5'-amine nucleoside, where the

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• butyric acid 209. Based on this, fullerene dimer 210 with four hydrogen bonds having a very high dimerization constant was obtained (Scheme 43). Diethyl 4-oxopimelate was used as the precursor of polymer 213. The former was converted via diacid 211 to the target methanofullerene 212, the solution of which

• synthetic route to conjugates of C60 with cinnamaldehyde 206 and with chalcone 207. The synthetic route to conjugate C60 with a 2-nitrocinnamyl group. The synthetic route to a C60 dimer connected through a highly directional fourfold hydrogen bonding motif. The synthetic route to quadruple hydrogen‐bonded

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

Amino- and polyaminophthalazin-1(2H)-ones: synthesis, coordination properties, and biological activity

• Zbigniew Malinowski,
• Emilia Fornal,
• Agata Sumara,
• Renata Kontek,
• Karol Bukowski,
• Beata Pasternak,
• Dariusz Sroczyński,
• Joachim Kusz,
• Magdalena Małecka and
• Monika Nowak

Beilstein J. Org. Chem. 2021, 17, 558–568, doi:10.3762/bjoc.17.50

• unit. Their geometry was fully optimized in vacuum using the DFT method with the crystal structure coordinates as the input geometry (optimized at the CAM-B3LYP/6–311++G(d,p)/LanL2DZ(Cu) level of theory). However, due to the convergence failure during the geometry optimization of the dimer of molecules

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• upon interaction. These results demonstrated that the site-specific 19F signal of 5-FTrp187 could be directly employed as a reliable reporter to monitor the monomer/dimer exchange dynamics. Moreover, it could also be employed to characterize the ED helix–helix dimer interface in more detail by means of

• boosted the overall spectral sensitivity even when minimal protein concentrations were employed. The structural dynamics of the Myc-Max dimer formation were then evaluated by using intermolecular PREs between 19F‐Myc and three differently paramagnetic spin labelled MTSL ([(1-oxyl-2,2,5,5-tetramethyl-Δ3

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• (cyclooctene)iridium dimer ([Ir(coe)2Cl]2) can act as the catalyst in combination with Et2SiH2 [15]. Surprisingly, they were able to obtain imines as well as amines using this methodology. Based on the works of Nagashima [16], an iridium-based protocol for tertiary amides was introduced by Dixon [17][18][19

Molecular basis for protein–protein interactions

• Brandon Charles Seychell and
• Tobias Beck

Beilstein J. Org. Chem. 2021, 17, 1–10, doi:10.3762/bjoc.17.1

• -dependence is β-lactoglobulin. The protein forms a dimer at a low pH value, while it is a tetramer at a higher pH value [51]. In a salt-dependent binding mechanism, the binding interaction occurs due to the changes in the solvent exposure of the charges in the contact residues before and after binding. This

• . Different residues at the ‘a’ and ‘d’ positions give rise to different oligomeric states, with the yeast transcription factor GCN4 being a perfect example of this. GCN4 has isoleucine as ‘a’ and leucine as ‘d’ and forms a dimer (Figure 2b). When isoleucine and leucine are swapped via mutagenesis, a tetramer

Chiral anion recognition using calix[4]arene-based ureido receptors in a 1,3-alternate conformation

• Tereza Horáčková,
• Jan Budka,
• Vaclav Eigner,
• Wen-Sheng Chung,
• Petra Cuřínová and
• Pavel Lhoták

Beilstein J. Org. Chem. 2020, 16, 2999–3007, doi:10.3762/bjoc.16.249

• same time, the carbonyl groups from the neighbouring receptor urea moieties interacted with the C–H bonds of the DMSO methyl group (the C=O···H–C distances were 2.486 and 2.452 Å), thus forming the calixarene dimer with a head-to-tail mutual orientation. The overall supramolecular binding motif was

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• formation of a new derivative of caffeine. Keywords: adenine; caffeine; cyclic dimer of hexafluorothioacetone; hexafluoroisopropyl group; purine; 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane; theophylline; Introduction Despite significant progress in the last 20–30 years, the selective introduction of

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• only the cis isomer coordinates to the Ni(II) for steric reasons and 3. intermolecular coordination. At higher concentrations dimer formation or coordination oligomers between trans record player molecules occurs [35]. To compare the new molecules (1f–j) with previous systems (1a–d), the switching

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• exhibits an emission maximum peak at 329 nm upon excitation at 294 nm. This emission band is probably due to the formation of the ground-state dimer by interaction between the benzene rings upon excitation or excimer emission caused by the interaction between the aromatic rings [41][43]. As the