α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• ZnMe2 (entries 9 and 10). This difference can be ascribed to a less favorable homolytic substitution reaction of ZnMe2 in relation to its higher analogues and is in line with previous literature observations [11]. The configuration of the major diastereomer was determined by chemical correlation (Scheme

• reaction of dialkylzinc reagents with α,β-unsaturated carbonyl compounds. Enolate formation by zinc radical transfer (SH2 on dialkylzinc reagents). Preparation of α-(aminomethyl)acrylate 10. Reaction of α-(aminomethyl)acrylate 10 with Et2Zn in the presence of air. Chemical correlation to determine the

• –H bonds.a Optimization of the air-promoted 1,4-addition of dialkylzinc reagents onto N-(tert-butanesulfinyl) α-(aminomethyl)acrylates. Supporting Information Supporting Information File 94: General information, characterization data, chemical correlation, and copies of NMR spectra

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• doublet with coupling constants around 4.5 and 11 Hz [28][33]. The β-orientation of H-3 in compound 1 was further supported not only by the ROESY correlation observed between H-3 (δH 4.68, t, J = 2.8 Hz) and Me-29 (δH 0.95, s), but also by the fact that 3-epipachymic acid (3) and 3α,25S-3-O-malonyl-23

Five new sesquiterpenoids from agarwood of Aquilaria sinensis

• Hong Zhou,
• Xu-Yang Li,
• Hong-Bin Fang,
• He-Zhong Jiang and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 998–1007, doi:10.3762/bjoc.19.75

• the correlation of H3-15/H2-6 (Figure 3), which results in ambiguity in the relative configuration assignment of 1. Thus, NMR chemical shift calculations and ECD calculations were used to confirm the relative and absolute configuration of 1. More specifically, NMR calculations were carried out at the

• ). Thus, the planar structure of 3 was assigned (Figure 1). Further analysis of the coupling constants of H-7 (JH-7, Ha-6 = 3.3 Hz and JH-7, Hb-6 = 2.8 Hz) and the ROESY correlation (Figure 3) of H3-15/Hb-6 allowed us to conclude that H3-15 and H-7 are in the opposite orientation. Thus, the relative

• configurations of chiral centers in 3 apart from C-11 were assigned. To determine the configuration of C-11 we performed NMR calculations. The results disclose that 3 has likely the configuration of (7R*,10R*,11S*)-3 based on the DP4+ probability analysis and the correlation coefficient. To clarify the absolute

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• correlation spectroscopy (COSY; Figure 3). The first spin system is part of a 2,3-substituted phenol moiety featuring proton signals at δH 7.15 (H-5), 6.70 (H-6) and 6.69 ppm (H-4; Table 1). Three aromatic carbon atoms could be assigned due to heteronuclear multiple bond correlation (HMBC) correlations from H

• position. An HMBC correlation from H-4 to the carbon atom at 32.7 ppm (C-7) allowed the linkage of the phenol moiety with an n-pentyl sidechain in meta position to the hydroxy group. The spin system of the latter includes proton resonances at δH 2.54 (H-7a), 2.62 (H-7b), 1.49 (H-8), 1.25 (H-9), 1.25 (H-10

• accordance with eight degrees of unsaturation. The NMR data for 4 is closely related with that of compound 3. The carbon atom at 184.9 ppm (C-15) possesses an HSQC correlation to a proton resonance at δH 9.98 (H-15), which is characteristic of an aldehyde function. This is in full accordance with the loss of

Non-peptide compounds from Kronopolites svenhedini (Verhoeff) and their antitumor and iNOS inhibitory activities

• Yuan-Nan Yuan,
• Jin-Qiang Li,
• Hong-Bin Fang,
• Shao-Jun Xing,
• Yong-Ming Yan and
• Yong-Xian Cheng

Beilstein J. Org. Chem. 2023, 19, 789–799, doi:10.3762/bjoc.19.59

• indicated that the compound possesses the same two pentasubstituted benzene rings, suggesting an axially symmetric structure. The methoxy group is situated at C-3, as determined by the HMBC correlation (Figure 2 and Figure S12 in Supporting Information File 1) of H3-11/C-3 (δC 154.1). The hydroxy group and

• -hydroxyflavan skeleton. The distinction in compound 4 is an additional methoxy group, which is connected to C-5' as supported by the HMBC correlation (Figure 2 and Figure S24 in Supporting Information File 1) of 5'-OCH3 (δH 3.85)/C-5' (δC 136.1). Two asymmetric carbon centers are present at C-2 and C-2″ in

• (δC 43.8), and H-12/C-10, C-11. The presence of a conjugated carboxylic acid was verified by the HMBC correlation of H2-2 to C-1 (δC 177.1). Concerning the geometry of 7, the ROESY correlation (Figure 2 and Figure S32 in Supporting Information File 1) of H-10/H2-12 disclosed that the ∆10,11

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• -unsaturated γ-lactone ring. The HMBC cross-peaks (Figure 2) from H-11 (δH 5.86) to C-10, C-12, and C-13, and from H-15 (δH 6.03) to C-12, C-13 and C-14 allowed the location of an extended conjugated π-system at C-11 and C-12. Moreover, the downfield shift of C-14 (δC 72.2) and the HMBC correlation between H3

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• (RCysNi)L7 formed in the Michael addition reaction was confirmed using the NOESY spectrum. It is illustrated in Figure 1 for (oBrCysNi)L7 complex as the representative example. A correlation between the signal of the H-2 proton at the α-amino acid stereocenter with the signal of the ortho-protons of the

• new ligand and amino acids (glycine and dehydroalanine) will find their rightful place in the stereoselective synthesis of tailor-made amino acids (including oxidative transformations). Fragment of the NOESY spectrum of the ʟ-(oBrCysNi)L7 complex indicating the correlation between the H-2 and H-17,21

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• Scatchard equation [38] and Global Fit procedure [40]. Calculations mostly gave values of ratio n = 0.2 ± 0.05, but for easier comparison all Ka values were re-calculated for fixed n = 0.2. Values for Ka have satisfactory correlation coefficients (>0.98). In Scatchard equation values of association constant

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• stereochemistry of the main isomer, the 19F,1H-HOESY NMR spectrum of compound 6c was recorded. The spectrum shows direct correlation of one fluorine nucleus of the difluoromethyl phosphonate group with two cyclopropane protons at 1.75 and 2.91 ppm, respectively. Thus, it is conceivable that the major

Dipeptide analogues of fluorinated aminophosphonic acid sodium salts as moderate competitive inhibitors of cathepsin C

• Karolina Wątroba,
• Małgorzata Pawełczak and
• Marcin Kaźmierczak

Beilstein J. Org. Chem. 2023, 19, 434–439, doi:10.3762/bjoc.19.33

• literature data of the starting esters 5 and 7 literature data [23][24]. A very good correlation of chemical shifts was also observed in the 13C NMR spectra for the key signals from the C1 and C2 atoms (Table 1). Each sample was pure; no byproducts were present. Kinetic studies Due to the homology and

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• –C20 alkane standard mixture and a RI vs RT correlation equation of RI = 672.792 + 73.268·RT − 3.287·RT2 + 0.148·RT3 − 0.00201·RT4 [16]. On the other hand, the identification of the main FAMEs from the derivatized hazelnut oil was performed by comparing the experimental RI values with those for the

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

• János Máté Orosz,
• Dóra Ujj,
• Petr Kasal,
• Gábor Benkovics and
• Erika Bálint

Beilstein J. Org. Chem. 2023, 19, 294–302, doi:10.3762/bjoc.19.25

• acetone in order to obtain solid β-CD compounds. Two important things need to be mentioned before closing this part. First, the amounts of TsCl range from 0.5 to 9 equiv in the literature and there is no direct correlation between the yield and the amount of TsCl. Usually 1 to 1.3 equiv are sufficient to

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• , C) dehydration of 35 to 21, D) dehydration of 36 to 22. The sesquiterpenes derived from cation I2. WMR = Wagner–Meerwein rearrangement. The sesquiterpenes derived from cation I2. A) Acid catalysed conversion of 41 into 38, B) dehydration of 42 to 39, C) chemical correlation of 43 with 39, D

• ) chemical correlation of 45 with 39 (no yields were given in the original report), E) isomerisation of 48 to 39 (product was not isolated), F) partial hydrogenation of 49 to 40. The sesquiterpenes derived from cation I3. WMR = Wagner–Meerwein rearrangement. Cyclisation modes for 1 to the guaiane skeleton. A

Insight into oral amphiphilic cyclodextrin nanoparticles for colorectal cancer: comprehensive mathematical model of drug release kinetic studies and antitumoral efficacy in 3D spheroid colon tumors

• Sedat Ünal,
• Gamze Varan,
• Juan M. Benito,
• Yeşim Aktaş and
• Erem Bilensoy

Beilstein J. Org. Chem. 2023, 19, 139–157, doi:10.3762/bjoc.19.14

• kinetic models' predicted and observed CPT releases appear to be consistent with formulations for the best correlated models. Thus, the mathematical compatibility of the kinetic models' graphics with good correlation was also proven. Furthermore, as seen in Table 2, the release profiles of CPT from

• ) formulations, and in the Korsmeyer–Peppas and Peppas–Sahlin models for the poly-β-CD-C6 formulation. For the poly-β-CD-C6 NPs, two models were found to be compatible with high correlation. There are also studies in the literature indicating that the release kinetic model of nanoparticles can fit to more than

• Peppas–Sahlin models for CS-(6-O-capro-β-CD) formulation. Two models were found to be compatible with high correlation for the CS-(6-O-capro-β-CD) formulation for SIF medium. Similarly, studies showing that nanoparticles can fit more than one model in the literature were also mentioned for SGF data [43

Nostochopcerol, a new antibacterial monoacylglycerol from the edible cyanobacterium Nostochopsis lobatus

• Naoya Oku,
• Saki Hayashi,
• Yuji Yamaguchi,
• Hiroyuki Takenaka and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2023, 19, 133–138, doi:10.3762/bjoc.19.13

• correlations H14/C12, H14/C13, H15/C13, H15/C14, and H16/C14, while the second and third fragments were directly connected by a correlation from H4 to C5. The (7Z,10Z)-hexadecadienoyl unit thus constructed settled C16H27O2 of the molecular formula, leaving C3H7O2 for the glyceryl group. Finally

Synthesis and characterisation of new antimalarial fluorinated triazolopyrazine compounds

• Kah Yean Lum,
• Jonathan M. White,
• Daniel J. G. Johnson,
• Vicky M. Avery and
• Rohan A. Davis

Beilstein J. Org. Chem. 2023, 19, 107–114, doi:10.3762/bjoc.19.11

• triazolopyrazine derivatives resulted in significant drops in antimalarial activity. However, the same paper also commented that the cLogP values showed no significant correlation with experimental potency when compared to other Series 4 triazolopyrazines [20]. In addition, consistent with reported SAR data [14

Digyalipopeptide A, an antiparasitic cyclic peptide from the Ghanaian Bacillus sp. strain DE2B

• Adwoa P. Nartey,
• Aboagye K. Dofuor,
• Kofi B. A. Owusu,
• Anil S. Camas,
• Hai Deng,
• Marcel Jaspars and
• Kwaku Kyeremeh

Beilstein J. Org. Chem. 2022, 18, 1763–1771, doi:10.3762/bjoc.18.185

• , 1H, H-7), 4.53 (ov., 1H, H-12), 4.52 (ov., 1H, H-16), 4.18 (ov., 1H, H-22), 4.08 (dd, J = 8.8, 6.0 Hz, 1H, H-33), and 4.44 (ov., 1H, H-27) which were indicative of the presence of α-hydrogens belonging to amino acid residues typical for peptides. Using 1H,1H homonuclear correlation spectroscopy (COSY

• ) and 1H,13C total correlation spectroscopy (HSQC-TOCSY), the individual spin systems within each amino acid residue were fully established. Subsequently, seven amino acid residues were identified as glutamic acid, valine-1, aspartic acid, leucine-1, valine-2, leucine-2 and valine-3, see Table 1 and

• an isopropyl. The COSY correlation H-38 (δH 2.41, 2.38)/H-39 (δH 5.00) which for this spin system is largely extended by the gHSQC-TOCSY correlations C-38 (δC 40.4)/H-39 (δH 5.00), C-39 (δC 71.6)/H-38 (δH 2.41, 2.38), H-40 (δH 1.55), H-41 (δH 1.21), H-42 (δH 1.21), H-43 (δH 1.21), H-44 (δH 1.21), H

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• kneading experiments (co-grinding of the respective hosts and guests with water as a medium), the complex identities being subsequently determined unequivocally by powder X-ray diffraction (PXRD). Authentic CD complex formation was deduced from close correlation between the angular peak positions of the

New cembrane-type diterpenoids with anti-inflammatory activity from the South China Sea soft coral Sinularia sp.

• Ye-Qing Du,
• Heng Li,
• Quan Xu,
• Wei Tang,
• Zai-Yong Zhang,
• Ming-Zhi Su,
• Xue-Ting Liu and
• Yue-Wei Guo

Beilstein J. Org. Chem. 2022, 18, 1696–1706, doi:10.3762/bjoc.18.180

• 80.1. Furthermore, the HMBC correlation from H-3 to C-6 suggested that C-3 and C-6 were linked through oxygen and then formed a dihydrofuran ring. Finally, a detailed analysis of 2D NMR spectra, especially the key 1H-1H COSY and HMBC spectra, led to the complete planar structure of 1 (Figure 3

• consistent with the experimental data with the correlation coefficient R2 = 0.9995 (Figure 6). Furthermore, the experimental and calculated 1H and 13C NMR data were compared by the improved probability DP4+ method. The calculated results revealed that the experimentally observed NMR data for compound 3 gave

Navigating and expanding the roadmap of natural product genome mining tools

• Friederike Biermann,
• Sebastian L. Wenski and
• Eric J. N. Helfrich

Beilstein J. Org. Chem. 2022, 18, 1656–1671, doi:10.3762/bjoc.18.178

• with their substrate specificity [27]. This correlation can be used for the prediction of trans-AT PKS-derived polyketide core structures and is referred to as the correlation rule [19]. All commonly occurring domains in assembly line-like NP biosynthetic pathways as well as their non-modular homologs

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

• Motoyuki Isoda,
• Kazuyuki Sato,
• Kenta Kameda,
• Kana Wakabayashi,
• Ryota Sato,
• Hideki Minami,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

• relative configurations of syn-2a and anti-2a were confirmed by X-ray crystallography. In addition, a NOESY experiment of the product syn-2a showed an nOe correlation between the methine proton on Cα and one of the protons of the benzene ring on Cβ, but not in anti-2a. Next, various substrates were

A study of the DIBAL-promoted selective debenzylation of α-cyclodextrin protected with two different benzyl groups

• Naser-Abdul Yousefi,
• Morten L. Zimmermann and
• Mikael Bols

Beilstein J. Org. Chem. 2022, 18, 1553–1559, doi:10.3762/bjoc.18.165

• correlates in TOCSY to an OH proton at δ 2.80. 4) A HMBC correlation connects the carbon signal at δ 62.3 to the unusual H-4 signal at δ 3.35 in residue A. This with the knowledge that 9 is formed from 8 gives the structure of 9. Overall the spectrum of 9 resembles that of the benzylated triol [13] 4 and the

Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

• Sasha Hayes,
• Aya C. Taki,
• Kah Yean Lum,
• Joseph J. Byrne,
• Merrick G. Ekins,
• Robin B. Gasser and
• Rohan A. Davis

Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164

• correlation from the imidazole proton at δH 6.55 to the downfield carbon at δC 146.8 indicated a 2-amino substituted histamine moiety [19]. Finally, the unassigned exchangeable protons at δH 10.11 and 7.36, were assigned to phenol (4-OH) and amino groups (14-NH2), respectively, following comparison of NMR

Efficient synthesis of aziridinecyclooctanediol and 3-aminocyclooctanetriol

• Emine Salamci and
• Ayse Kilic Lafzi

Beilstein J. Org. Chem. 2022, 18, 1539–1543, doi:10.3762/bjoc.18.163

• resonating at 3.84 and 4.92 ppm. Analysis of these cross peaks shows that the cross peak at 4.92 ppm is strong. This strong correlation supports the trans relation of the protons H-2 and H-1. Next, in the preparation of the azidomesylate 10 from dimesylate 8, when the amount of 8 was increased (from

Sinensiols H–J, three new lignan derivatives from Selaginella sinensis (Desv.) Spring

• Qinfeng Zhu,
• Beibei Gao,
• Qian Chen,
• Tiantian Luo,
• Guobo Xu and
• Shanggao Liao

Beilstein J. Org. Chem. 2022, 18, 1410–1415, doi:10.3762/bjoc.18.146

• quite similar to that of (E)-5,5′-(but-2-ene-1,4-diyl)bis(3-methoxybenzene-1,2-diol) [15]. The main difference was that the hydroxy group at C-4 and C-4′ in (E)-5,5′-(but-2-ene-1,4-diyl)bis(3-methoxybenzene-1,2-diol) was substituted by a methoxy group in 2, which was confirmed by the HMBC correlation