Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

• Jin Yang,
• Dang-Wei Qian and
• Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

• 3ai was obtained in 21% yield, while the meta-methyl-substituted derivative 1h was converted into the corresponding product 3ah in 63% yield. In addition, the configuration of 3ak was determined by an X-ray crystallographic analysis (CCDC 2177793). To our delight, phosphorus sources containing a

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• Figure 2). The protons of the ester group linked to the cyclopropane moiety exhibit correlation with the methylene protons of proline in the NOESY spectrum. Thus, the ester groups are at the same side of the Ni coordination plane as the proline methylene groups indicating the (S) configuration of the α

• -stereocenter. The large positive value of the specific rotation ([α]D +1770) additionally supports α-(S) configuration since positive [α]D values are characteristic for the Ni–Schiff base complexes of (S)-N-(N-benzylprolyl)aminobenzophenone and ʟ-amino acids [48]. To choose the most promising candidates for

• configuration to the α-stereocenter as (R) in both thermodynamically and kinetically controlled isomers of 10. The configurations of the β-stereocenter in the obtained diastereomers of 10 are different, as follows from the different correlations of the ortho-phenyl protons of the benzophenone moiety observed in

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

• hangtaimycin, starting from ʟ-tryptophan is presented. Comparison to TDD isolated from the hangtaimycin producer Streptomyces spectabilis confirmed its S configuration. The X-ray structure of the racemate shows an interesting dimerisation through hydrogen bridges. The results from bioactivity testings of

• against Bacillus subtilis [1]. Together with a structural revision from 29Z to 29E configuration and further biological evaluation of its hepatoprotective properties, its biosynthetic gene cluster was recently identified [2]. The biosynthetic machinery is composed of a hybrid trans-acyltransferase (trans

• configuration of hangtaimycin have not yet firmly been established, 2 is known to be S-configured and is derived from an ʟ-alanine unit [2]. TDD (4) was recently suggested to be R-configured, containing a ᴅ-tryptophan unit, based on a comparison of the optical rotation of the isolated compound ([α]D20 = −12.67

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

• ’’-coupled dimer (Table S5, Supporting Information File 1). For the dimer 3, three hydroxy and fifteen sp2 protons indicated a C–O bond linkage. An analysis of 1H,1H-COSY and HMBC spectra suggested it to be a 3’–O–7’’-coupled dimer (Table S6, Supporting Information File 1). The absolute configuration of 1

• equal to the monomers 4 and 6, 1 displayed a roughly twofold radical scavenging capacity (Figure S9, Supporting Information File 1). This is in agreement with the previous report that the configuration of the hydroxy group of the B-ring plays a key role in the antioxidant activity [34]. Thus, CYP158C1

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

• ). Using more reactive (electron-rich) arenes results in lower diastereoselectivity and regiospecificity of the reaction (cf. 9q, 9v, and 9w). The structure and the initially anticipated trans-configuration of the products 9 was unequivocally confirmed by 1H and 13C NMR spectroscopy as well as, in the case

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• ) [22]. Based on optical rotation values and biosynthetic correlation to known azodyrecins, the configuration of compounds 7–10 was defined to be 2S. Fractionation guided by the N2H4-detecting assay revealed that compounds 1–10 were also produced by Streptomyces sp. A1C6 (Figure S2 in Supporting

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• . Furthermore, the absolute configuration of C-4 and C-5 in compound 1 was also confirmed as 4R and 5S by X-ray crystallography (Figure 2). (±)-Daturamycin B (2) was isolated as a white powder, and its molecular formula was determined as C17H14O3 by HRMS–ESI data (m/z 289.0833 [M + Na]+, calcd for C19H16O5Na

• suggested that the relative configurations of C-4 and C-5 were trans. Therefore, the structure of compound 2 has been determined, as shown in Figure 1. However, the absolute configuration of compound 2 remained unsolved. Daturamycin C (3) was obtained as a brown powder, and the 1H and 13C NMR spectra

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 991–998, doi:10.3762/bjoc.18.99

• relative configuration. For explaining the formation of the two kinds of the compounds, a plausible reaction mechanism was proposed on the basis of the previous works [30][31][32][33][34][35] and the present experimental results (Scheme 2). As described in the previous work, TBAF can act as an effective

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

• chamber (Figure 1). The requirement for a divided cell (a more complicated device than the undivided configuration) arises from the need to protect electrogenerated NHC from its anodic oxidation in the absence of a consumable anode. To ensure good sealing of the electrolysis cell, the sandwich-type

• arrangement of cell components was compressed between two end plates using a series of bolts. This design incorporated a solution inlet and a solution outlet for the chamber to allow uniform flow over the surface of the electrodes. In the present work, where a divided cell configuration was required, a proton

Anti-inflammatory aromadendrane- and cadinane-type sesquiterpenoids from the South China Sea sponge Acanthella cavernosa

• Shou-Mao Shen,
• Qing Yang,
• Yi Zang,
• Jia Li,
• Xueting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 916–925, doi:10.3762/bjoc.18.91

• enantiomers [(+)-4/(−)-4 and (+)-5/(−)-5], respectively, by using chiral-phase HPLC. The structures of new compounds were elucidated by extensive spectroscopic analysis and comparison with the reported data. In addition, the absolute configuration of optically pure (+)-1 and 2 were determined by time

• product of squamulosone [aromadendr-1(10)-en-9-one] by the fungus Curvularia lunata ATCC 12017 [19], indicating (+)-1 and (−)-1 were enantiomeric each other. To secure the absolute configuration of optically pure (+)-1, a TDDFT-ECD calculation, which has proven to be a reliable tool for the absolute

• configuration determination of natural products with stereogenic centers near the chromophore groups [20], was applied, since there is an α,β-unsaturated ketone chromophore nearby C-5 and C-2 in compound (+)-1. Thus, the theoretical ECD spectrum of (+)-1 was calculated by the DFT calculation method at the b3lyp

The stereochemical course of 2-methylisoborneol biosynthesis

• Binbin Gu,
• Anwei Hou and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 818–824, doi:10.3762/bjoc.18.82

• ]. Recent research on its chemical ecology demonstrated that arthropodes are attracted by compound 1 which helps in the dispersion of Streptomyces spores [20]. The absolute configuration of (–)-1 has been established through a synthesis from (+)-camphor [21]. The biosynthesis of compound 1 was initially

Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures

• Mengjie Wang,
• Lanping Dang,
• Wan Xu,
• Zhiying Ma,
• Liuliu Shao,
• Guangxia Wang,
• Chunli Li and
• Hua Wang

Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81

• helicenes have the same configuration and bend toward the same direction on the same side of the shared naphthalene ring (Figure 3C and D). Both products DH-1 or DH-2 feature a pair of enantiomers MM and PP in their unit cell (see Supporting Information File 2, Figures S2 and S6). The crystal parameters of

• obviously differ because of changes in their molecular configuration and equal to 2.86, 3.15, and 3.81 eV, respectively [27][28]. As the number of selenium atoms increases from DH-1 to DH-3, the fluorescence intensity (Figure S19 in Supporting Information File 1) and the fluorescence quantum yield (ΦF

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• ’, 1j’ were successfully isolated and fully characterized. Notably, the relative configuration of major isomer 1f (CCDC 2109575) was determined by X-ray crystallographic analysis, in which the m-chlorophenyl, benzoyl and the phenyl group in oxindole are in cis-configuration. It has been known that the

• ’ and 2g’ were also isolated and fully characterized. Moreover, the relative configuration of major isomer 2b (CCDC 2109576) and minor isomer 2g’ (CCDC 2109577) were determined by X-ray crystallographic analysis. In the major isomer 2b, the phenyl group at C4-position is in cis-position to the aryl

• group in the oxindole scaffold, while these two groups exist in trans-configuration in the minor isomer 2g’. 5-Arylidene-1,3-dimethylbarbituric acids, as good dienophiles, could also react smoothly in such a catalytic system (Scheme 4a). Firstly, the three-component reaction of 2-methylindole, 5

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

• -hindered face of TPC (2a) is more favorable than the opposite diastereoisomer 3a' (Scheme 2). Subsequently, our hypothesis about the relative configuration of 3a was confirmed by X-ray analysis that was carried out for the related compound 3e (vide infra). Subsequently, our efforts focused on the

• triple bonds due to ring strain. It is noteworthy that we managed to determine the relative configuration of cycloadduct 3e by carrying out the corresponding X-ray structural analysis (Figure 1 and Table S2 in Supporting Information File 1). As anticipated, the azomethine ylide 1 cycloaddition to

• . The constitution of compounds 3b–g was established by analyzing 1H and 13C NMR spectra. In line with the structure of meso compound 3e, the relative configuration, that is shown in Scheme 3, was assigned to cycloadducts 3a, 3c, 3d, 3f, and 3g. Thus, the cycloadditions of 3-substituted-1,2

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

• -configuration. These biochemical and biophysical analyses of NvfI suggested that NvfI catalyzes the endoperoxide formation reaction through a different mechanism from those of COX and FtmOx1. Further computational studies and mechanistical studies are now in progress in our laboratories to clarify the molecular

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

• Hui Zheng,
• Ying Han,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• [cyclohexane-1,3'-indolines] and the Z/E-configuration of the exocyclic C–C double bonds, several diastereoisomers might be formed in the obtained products. The 1H NMR spectra clearly indicated that the obtained products contain two isomers with ratios in the range of 3:1 to 6:1. Thus, it was disappointing to

• (thiophen-2-yl)penta-1,4-dien-3-one was also successfully employed in the reaction. The major isomers of the corresponding spiro compounds 3x and 3y were predominately produced in moderate yields. In order to determine the relative configuration of the spiro compounds, the single crystal structures of the

• aryl group exist on the cis-position of the carbonyl group on the exocyclic C=C bond (Z-configuration). Thus, it can be concluded that the major isomers 3a–z have this kind of the relative configuration. In Figure 3, the aryl group and the carbonyl group of the oxindole scaffold also exist on trans

Heteroleptic metallosupramolecular aggregates/complexation for supramolecular catalysis

• Prodip Howlader and
• Michael Schmittel

Beilstein J. Org. Chem. 2022, 18, 597–630, doi:10.3762/bjoc.18.62

• allows, as demonstrated by Nature by the multicomponent ATP synthase motor, a more detailed and refined configuration of purposeful machinery. Furthermore, (metallo)supramolecular catalysis is shown to extend beyond the single "supramolecular unit" and to reach far into the field and concepts of systems

• multicomponent ATP synthase motor [23], a more detailed and refined configuration of purposeful machinery [24]. For the preparation of heteroleptic aggregates, one must differentiate between dynamic (rapidly exchanging) and kinetically inert heteroleptic metal–ligand interactions. While the inert heteroleptic

Terpenoids from Glechoma hederacea var. longituba and their biological activities

• Dong Hyun Kim,
• Song Lim Ham,
• Zahra Khan,
• Sun Yeou Kim,
• Sang Un Choi,
• Chung Sub Kim and
• Kang Ro Lee

Beilstein J. Org. Chem. 2022, 18, 555–566, doi:10.3762/bjoc.18.58

• -hydroxy-glechoman-8,12-olide (DHG) indicated that 1 could be the glucopyranosyl-DHG [8]. The HMBC cross peak from H-1' (δH 4.20) to C-8 (δC 109.2) suggested a glucopyranosyl unit located at C-8 (Figure 2A). The relative configuration of 1 was established based on comparison of 1H NMR data with the

• the same orientation as 8α-DIG. Also, the NOESY spectrum of 1 showed cross peaks between H3-14, H-3a/H-2a; H-3a, H-6a/H3-15 indicating their α-orientation, whereas the NOESY cross peaks of H-1, H-1'/H-9b; H-3b, H-6b/H-5 suggested their β-orientation (Figure 2A). The absolute configuration of 1 was

• ) (Supporting Information File 1, Figure S8), and the coupling constant of the anomeric proton (J = 7.8 Hz), confirmed it as being in the β-configuration [11]. Thus, the structure of 1 was determined as (1S,4S,5R,8S,10R)-1,10;4,5-diepoxy-8-O-β-ᴅ-glucopyranosyl-glechoman-8,12-olide. Compound 2 was obtained as a

BINOL as a chiral element in mechanically interlocked molecules

• Matthias Krajnc and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2022, 18, 508–523, doi:10.3762/bjoc.18.53

• and P isomers), similar to (S,S)-5 (see Figure 2). Secondly, the embedding of the DNP unit in the tetracationic cyclophane leads to an element of planar chirality (Rp and Sp isomers). Thus, for each configuration of BINOL, four different diastereoisomers are possible. However, for these specific

• rotaxanes, the helicity is predetermined by the planar chirality (based on the underlying macrocycle–macrocycle interactions), so that only two diastereoisomers remain for a given BINOL configuration (e.g., (R)-(Rp) and (R)-(Sp) in case of (R)-BINOL). In contrast to the axial chirality of the BINOL unit

• chirality transfer from the macrocycle onto the polymers. Accordingly, use of the enantiomeric macrocycles (S)-12 and (R)-12 gives rise to polyacetylenes with an opposite helix sense. Interestingly, employing the bis-BINOL macrocycle (R)-26 led to an inversed helix configuration in comparison to the mono

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• were identified by analysis of their spectroscopic data. The relative configuration was assigned based on NOEDIFF data. The absolute configuration of compound 1 was established according to specific rotations and ECD data while that of compound 2 was proposed based on biosynthetic considerations

• ] (Figure 1). Their structures were elucidated on the basis of analysis of their spectroscopic data including IR, UV, NMR, and MS. The relative configuration was assigned based on NOEDIFF data. Furthermore, the absolute configuration of compound 1 was determined by comparison of its specific rotation and

• ) together with the chemical shift of C-3 indicated that the 3-OH group in compound 3 was replaced by a carboxyl group in compound 1. The relative configuration was determined by the NOEDIFF data (Figure 2). A signal enhancement of H-7, but not H-5, after irradiation of Hab-3, indicated an E-configuration of

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• device structure [17]. The OLED device structure applied the following configuration: –ITO/NPB [N,N’-di(1-naphthyl)-N,N’-diphenyl-(1,1’-biphenyl)-4,4’-diamine] (40 nm)/10% of 1 in CBP (20 nm)/TPBi [2,2’,2’’-(1,3,5- benzinetriyl)-tris(1-phenyl-1H-benzimidazole)] (20 nm)/BCP (bathocuproine)] (20 nm)/LiF (1

Four bioactive new steroids from the soft coral Lobophytum pauciflorum collected in South China Sea

• Di Zhang,
• Zhe Wang,
• Xiao Han,
• Xiao-Lei Li,
• Zhong-Yu Lu,
• Bei-Bei Dou,
• Wen-Ze Zhang,
• Xu-Li Tang,
• Ping-Lin Li and
• Guo-Qiang Li

Beilstein J. Org. Chem. 2022, 18, 374–380, doi:10.3762/bjoc.18.42

• structurally related compounds reported in the literature. The absolute configuration of 1–3 was determined by X-ray diffraction. All the compounds have assessed the cytotoxicity against HL-60, K562, and Hela cells. Compound 1 showed weak cytotoxicity against K562 cells with an IC50 value of 19.03 μM. In

• particular, compound 1 also has a tetracyclic skeleton with a methyl group at C-4. The absolute configuration of 1–3 was determined by X-ray analysis. Herein, we report the isolation, structure elucidation, and bioactivities of these compounds. Results and Discussion Compound 1 was isolated as a white powder

• -21 to C-17/C-20/C-22, and from H3-26 to C-24/C-25 confirmed the establishment of the carbon skeleton of the 23,24-dimethycholestane with a methyl group at C-4. Thus, the planar structure of 1 was established as shown in Figure 1. The relative configuration of 1 was deduced by the NOESY spectrum

Amamistatins isolated from Nocardia altamirensis

• Till Steinmetz,
• Wolf Hiller and
• Markus Nett

Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40

• help of COSY and HMBC data two residues were identified, including a threonine and a salicylic acid moiety. The two partial structures can be connected via an ester bond due to a key HMBC correlation from H-3 to C-5. To analyze the configuration of the isolated compounds, their optical rotations were

• compounds did not show any discrepancies in their NOESY spectra in comparison to 5. This suggests that 1, 3, 4, and 5 possess the same absolute configuration. Measurements of 2 were not possible due to the low quantity of isolated material, but it stands to reason that its configuration is identical to 5

• function. Due to the similarity of both molecules, we propose that compound 6 possesses the same absolute configuration as pseudomonin A. The affinities of compound 1–6 for the coordination of ferric iron were evaluated with the CAS assay [9] and compared with EDTA [13]. While the half-maximal displacement

Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• space group P212121. The presence of sulfur anomalous scatters allowed to unequivocally establish the absolute configurations, which reads S at the chiral center C2 and R at the C10 (C numbering as in Figure 1). The absolute configuration of the two sulfur stereogenic centers is confirmed to be R

• . Interestingly, the molecule does not bear any pseudo-mirror plane, that is, the observed conformer is asymmetric (C1) in itself, regardless the configuration of the two sulfinamide substituents. This peculiarity is likely due to the hindered rotation across the newly formed C–C bond, joining the two oxindole

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• (4 mol %) and ligand L2, the ring closure also took place regioselectively at the indole C3 position, albeit the products 3 were embedded with a seven-membered ring instead of a nine-membered one. The absolute configuration of products 3 was proposed to be S, based on the general rule of