New advances in asymmetric organocatalysis

• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 240–242, doi:10.3762/bjoc.18.28

• Waser employed an isothiourea catalyst for esterification-mediated kinetic resolution of paracyclophane derivatives with planar chirality [19]. Parida and Pan showed that a Michael reaction coupled with an acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones can produce a

Anomeric 1,2,3-triazole-linked sialic acid derivatives show selective inhibition towards a bacterial neuraminidase over a trypanosome trans-sialidase

• Peterson de Andrade,
• Sanaz Ahmadipour and
• Robert A. Field

Beilstein J. Org. Chem. 2022, 18, 208–216, doi:10.3762/bjoc.18.24

• and 4.79 ppm in 1H NMR, respectively. High-resolution mass spectra were acquired using electrospray ionisation in a Waters Vion spectrometer with Waters Acquity LC–MS (positive mode). Fluorescence measurements were performed on a FLUOstar Omega Multi-Mode Microplate Reader. Expression and purification

Diametric calix[6]arene-based phosphine gold(I) cavitands

• Gabriele Giovanardi,
• Andrea Secchi,
• Arturo Arduini and
• Gianpiero Cera

Beilstein J. Org. Chem. 2022, 18, 190–196, doi:10.3762/bjoc.18.21

• via conventional protocols using (Me2S)AuCl. Notably, the organometallic macrocycles A,B,C(AuCl)2 could be isolated via column chromatography separation. Gold(I) catalysts were subsequently fully characterized by NMR analysis and high-resolution mass spectrometry. The conformation of the catalysts, in

Synthesis and late stage modifications of Cyl derivatives

• Phil Servatius and
• Uli Kazmaier

Beilstein J. Org. Chem. 2022, 18, 174–181, doi:10.3762/bjoc.18.19

• degree of variability for the generation of small libraries, in our case of Cyl-1 derivatives. Chiral allylic alcohols are easily accessible, either via kinetic resolution of racemic alcohols [46][47], asymmetric catalysis [48], or from chiral pool materials, such as threitol 1 [49]. Using the last

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• characterized by powder Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) spectroscopy, etc. It was effectively utilized in the eco-friendly synthesis of

Bifunctional thiourea-catalyzed asymmetric [3 + 2] annulation reactions of 2-isothiocyanato-1-indanones with barbiturate-based olefins

• Jiang-Song Zhai and
• Da-Ming Du

Beilstein J. Org. Chem. 2022, 18, 25–36, doi:10.3762/bjoc.18.3

• spectra were measured at 100 MHz with a 400 MHz spectrometer or at 176 MHz with a 700 MHz spectrometer, chemical shifts are reported in δ (ppm) units relative to tetramethylsilane and referenced to solvent peak (CDCl3, δ = 77.00 ppm; DMSO-d6, δ = 39.43 ppm). High-resolution mass spectra were measured with

Unsaturated fatty acids and a prenylated tryptophan derivative from a rare actinomycete of the genus Couchioplanes

• Shun Saito,
• Kanji Indo,
• Naoya Oku,
• Hisayuki Komaki,
• Masashi Kawasaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2021, 17, 2939–2949, doi:10.3762/bjoc.17.203

• 13C NMR data, and high-resolution ESIMS data were presented. While an S-configuration was assigned for phialomustin B based on its positive specific rotation ([α]D25 +55.5, c 1.5, CHCl3) in comparison with those of synthetic standards [26], opposite negative signs in CHCl3 and MeOH ([α]D27 –12, c

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

• Samet Poyraz,
• Samet Belveren,
• Sabriye Aydınoğlu,
• Mahmut Ulger,
• Abel de Cózar,
• Maria de Gracia Retamosa,
• Jose M. Sansano and
• H. Ali Döndaş

Beilstein J. Org. Chem. 2021, 17, 2812–2821, doi:10.3762/bjoc.17.192

• coupling constants (J) are given in Hz and chemical shifts in ppm. Low-resolution electron impact (EI) mass spectra were obtained at 70 eV using a Shimadzu QP-5000 by injection or DIP; fragment ions in m/z are given with relative intensities (%) in parentheses. High-resolution mass spectra (HRMS) were

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• without further purification. 1H and 13C NMR spectra were acquired on a Bruker DPX 400 MHz spectrometer for one-dimensional experiments and on a Bruker Avance III 600 MHz for 19F NMR spectra and 2D-experiments (gHMBC). NMR spectra were recorded using 5 mm sample tubes, at 298 K, at a digital resolution of

• VERTEX 70 spectrophotometer with Platinum ATR accessory (diamond crystal) in the 4000–400 cm−1 region. High-resolution mass spectra (HRMS) were obtained for all compounds on a hybrid high-resolution and high-accuracy (5 μL/L) micro Q-TOF mass spectrometer (Bruker Scientific®, Billerica, MA, USA) at the

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• axial chiral compounds has been paid much attention [6], and great progress has been made in recent years. For example, many remarkable activities have been undertaken to develop strategies such as dynamic kinetic resolution, atroposelective coupling, cycloaddition, and chirality conversion for the

• (kinetic resolution) in the presence of chiral phosphoric acid CPA 3. In this work, various EWG- and EDG-containing substrates were incorporated, and chiral biaryls 10 were obtained with good to excellent selectivities of 81–93% ee by desymmetrization and 63–96% ee by kinetic resolution. The subsequent

• asymmetric addition reaction of racemic naphthylindole 42 with azodicarboxylate 43 under chiral phosphoric acid catalysis. In the presence of CPA 2, 42 and 43 reacted and underwent dynamic kinetic resolution to afford naphthylindoles 44 with axial chirality in moderate to good yields (50–98%) and high

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• ). Multiplicity is defined as s = singlet, d = doublet, t = triplet, q = quartet, p = pentet, m = multiplet. NMR spectra were analyzed with NMR software MestReNova, version 14.2.0-26256 (Mestrelab Research S.L.). High-resolution mass spectra were performed by the LMU Mass Spectrometry Service applying a Thermo

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

• -oxathiolane nucleosides via resolution methods. The chemical as well as enzymatic procedures are reviewed and segregated in this review for effective synthesis of 1,3-oxathiolane nucleoside analogues. Keywords: chiral auxiliaries; enzymes; Lewis acids; N-glycosylation; 1,3-oxathiolane sugar and nucleosides

• , ii) a stereoselective N-glycosylation process that is compatible with an enantiomerically pure substrate, and iii) separation of enantiomers by chemical or enzymatic resolution methods. This review summarizes the methods used to synthesize 1,3-oxathiolane nucleosides. Many methods provide the

• the logic while depicting comparison with the established series of nucleoside analogues. In chiral synthesis, it is often important to establish the ratio of enantiomers before focusing on the isolation of a specific enantiomer. Therefore, having a good overview on enzymatic and chemical resolution

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• transferred between the oxygen atoms after the alkyl migration, making it especially useful in synthetic strategies using these protected intermediates. Additionally, the reaction was found to be useful in the kinetic resolution of a racemic mixture of chiral substrates possessing both alkyl and aryl α

• . The catalyst is also capable of kinetic resolution of a mixture of enantiomeric substrates. Al* = 18. BF3-promoted diastereospecific rearrangement of α-ketol 21 to difluoroalkoxyborane 22. In the presence of a gold catalyst and water in 1,4-dioxane, 1-alkynylbutanol derivatives undergo tandem

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

• Luke O. Jones,
• Leah Williams,
• Tasmin Boam,
• Martin Kalmet,
• Chidubem Oguike and
• Fiona L. Hatton

Beilstein J. Org. Chem. 2021, 17, 2553–2569, doi:10.3762/bjoc.17.171

• deposition mechanisms, e.g., the maximum deposition force and/or syringe tip size (0.8 mm used for hydrogels) for certain printers, place restrictions on highly viscous materials. These material properties have a direct influence on the final printing resolution. The resolution should be adequate for

• been investigated for their printability for producing cryogel scaffolds [71]. These cryogels form crosslinks through physical interactions, hence no additional crosslinking was required. Some difficulties arise when designing 3D-printed cryogels. While precise resolution may be achieved, there is some

In-depth characterization of self-healing polymers based on π–π interactions

• Josefine Meurer,
• Julian Hniopek,
• Johannes Ahner,
• Michael Schmitt,
• Jürgen Popp,
• Stefan Zechel,
• Kalina Peneva and
• Martin D. Hager

Beilstein J. Org. Chem. 2021, 17, 2496–2504, doi:10.3762/bjoc.17.166

• KBr (Merck KGaA, Darmstadt, Germany) into a ∅ 12 mm-form under vacuum and 7 MPa pressure. The window was subsequently transferred into the temperature cell and secured with a lockring and teflon seals. A background spectrum with 32 scans and 4 cm−1 spectral resolution was recorded. 1 mg of the

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• detector was calibrated with polystyrene standards having narrow molecular-weight distributions. The data were analyzed using Eco-SEC analysis software. A Hitachi HT7700 (TEM) with EXALENS (120 kV) working at a high-resolution (HR) mode was used to obtain transmission electron microscopy (TEM) images, high

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• ) relative to tetramethylsilane (SiMe4) as internal standard. High-resolution MS (HRMS–ESI) was performed on an Agilent 1969 A TOF. The photophysical studies were carried out in freshly prepared dichloromethane solutions with concentrations of 1 × 10−5 M. The UV–vis spectra were recorded on a Shimadzu 2401

Targeting active site residues and structural anchoring positions in terpene synthases

• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2021, 17, 2441–2449, doi:10.3762/bjoc.17.161

• gaschromatographic analysis using a chiral stationary phase did not show any resolution for the enantiomers of 8 or 9, their enantiomeric composition was determined using the enantioselectively deuterated substrates (R)- and (S)-(1-13C,1-2H)GGPP [25]. Their conversion into different enantiomers of 8 and 9 will lead

Isolation and characterization of new phenolic siderophores with antimicrobial properties from Pseudomonas sp. UIAU-6B

• Emmanuel T. Oluwabusola,
• Olusoji O. Adebisi,
• Fernando Reyes,
• Kojo S. Acquah,
• Mercedes De La Cruz,
• Larry L. Mweetwa,
• Joy E. Rajakulendran,
• Digby F. Warner,
• Deng Hai,
• Rainer Ebel and
• Marcel Jaspars

Beilstein J. Org. Chem. 2021, 17, 2390–2398, doi:10.3762/bjoc.17.156

• from the Oyun river in North Central Nigeria. The structure of the new compounds, pseudomonin A–C (1–3) and pseudomobactin A and B (4 and 5) isolated alongside two known compounds, pseudomonine (6) and salicylic acid (7), were elucidated based on high-resolution mass spectrometry, 1D and 2D NMR

• Figure 1 and Supporting Information File 1 for details) which were comparable with those reported in the literature [28][36][37]. Pseudomonin A (1) was isolated as a yellowish compound. The molecular formula of C11H15O4N2 with 6 degrees of unsaturation was established by high-resolution ESI-Orbitrap-MS

Synthesis and antimicrobial activity of 1H-1,2,3-triazole and carboxylate analogues of metronidazole

• Satya Kumar Avula,
• Syed Raza Shah,
• Khdija Al-Hosni,
• Muhammad U. Anwar,
• Rene Csuk,
• Biswanath Das and
• Ahmed Al-Harrasi

Beilstein J. Org. Chem. 2021, 17, 2377–2384, doi:10.3762/bjoc.17.154

• methylene protons of –N–CH2-CH2–N3. A singlet peak at δ 2.50 was due to methyl protons on the imidazole ring. The high-resolution mass spectrometric data at 197.0737 (M + H)+ confirmed the structure of metronidazide 3. Single crystals of metroazide compound 3 were grown from slow evaporation of DCM solution

• protons of –N–CH2-CH2–Ph. A singlet peak at δ 1.86 is attributed to methyl protons on the imidazole ring. The 19F NMR spectrum of 1H-1,2,3-triazole compound 5c showed a singlet at δ −113.61 corresponding to one fluorine atom of the phenyl ring. The high-resolution mass spectrometric data at 317.1141 (M

• aromatic protons of the phenyl ring. A singlet signal at δ 7.95 is for the 1H-imidazole proton. Two doublet signals at δ 4.73 and δ 4.71 are assigned to the four methylene protons of –N–CH2-CH2–Ph. A singlet peak at δ 2.48 is due to the methyl protons on the imidazole ring. The high-resolution mass

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• maintain due to the conformational lability of the seleniranium ion [52][53][54], this initial problem can be exploited through the addition of an anion-binding catalyst. In this way, the configurational scrambling is used for a dynamic kinetic resolution during the intramolecular nucleophilic opening of

Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF₃·OEt₂ catalysis

• Karthikeyan Soundararajan,
• Helen Ratna Monica Jeyarajan,
• Raju Subimol Kamarajapurathu and
• Karthik Krishna Kumar Ayyanoth

Beilstein J. Org. Chem. 2021, 17, 2186–2193, doi:10.3762/bjoc.17.140

• (6a–f) were deduced from 1H NMR, 13C NMR, elemental analysis and high-resolution mass spectrometry. To account for the observed synthesis of indene from MBH adducts a model was suggested based on the reports of Rawal et al. [17][19], Katsuki et al. [20][21] and Jurczak et al. [22]. The proposed model

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• room temperature and with a high spatial resolution (the reaction only occurs in the light-irradiated areas). These latter photochemical processes are also very fast and efficient. However, energetic and unsafe UV light is usually used to ensure high polymerization rates and final reactive function

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

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123