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

• 7.02 (s, 1H, H-7)], two methoxy signals [δH 3.96 (s, 3H, H3-12) and 3.73 (s, 3H, H3-11)], and two methyl signals [δH 2.51 (s, 3H, H3-10) and 1.09 (d, J = 6.8 Hz, 3H, H3-9)]. The 13C NMR and DEPT spectra of compound 1 (Table 1 and Figure S2 in Supporting Information File 1) exhibit 14 resonances

• + H]+ ion peak at m/z 317.1008 (calcd for C17H17O6, 317.1020). The 1H NMR data (Table 2 and Figure S8 in Supporting Information File 1) reveal an aromatic signal [δH 7.47 (s, 2H, H-1, H-8)], a methoxy signal [δH 3.95 (s, 6H, H3-11, H3-14)], and a methyl signal [δH 2.48 (s, 6H, H3-12, H3-13)]. The 13C

• NMR and DEPT spectra (Table 2 and Figure S9 in Supporting Information File 1) show that compound 2 is comprised of 9 carbons, including one methyl, one methoxy carbon, one sp2 methine, one ketone, and five sp2 carbons (three of them oxygenated). The 1H and 13C NMR data and the molecular formula

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

• Constantine V. Milyutin,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Mikhail E. Minyaev and
• Valeriya G. Melekhina

Beilstein J. Org. Chem. 2023, 19, 778–788, doi:10.3762/bjoc.19.58

• result, both products could be isolated and characterized using 1H, 13C NMR spectroscopy and mass spectrometry. Moreover, the structure of product 11a was also confirmed by single-crystal X-ray diffraction analysis. It might be noted that precipitated crystals of 11a contained two polymorph modifications

• 11g–j were confirmed by 1H, 13C NMR spectroscopy and high-resolution mass spectrometry. In the 1H NMR spectra of the products, characteristic singlets corresponding to the protons of the dihydropyranone fragment in the region δ 5.3–5.4 ppm and the protons of the hydroxy group in the region δ 5.4–5.5

• photoproducts 11 and 12.a Supporting Information Supporting Information File 42: Experimental procedures, characterization data of all products, copies of 1H, 13C NMR, HRMS spectra of all new compounds, and X-ray crystallographic data.

Sulfate radical anion-induced benzylic oxidation of N-(arylsulfonyl)benzylamines to N-arylsulfonylimines

• Joydev K. Laha,
• Pankaj Gupta and
• Amitava Hazra

Beilstein J. Org. Chem. 2023, 19, 771–777, doi:10.3762/bjoc.19.57

• -pot synthesis of N-heterocycles. Optimization of reaction conditions.a Supporting Information Supporting Information File 112: General procedures, product characterization, and copies of 1H NMR and 13C NMR spectra of all compounds. Acknowledgements The authors acknowledge NIPER S.A.S. Nagar for

Bromination of endo-7-norbornene derivatives revisited: failure of a computational NMR method in elucidating the configuration of an organic structure

• Demet Demirci Gültekin,
• Arif Daştan,
• Yavuz Taşkesenligil,
• Cavit Kazaz,
• Yunus Zorlu and
• Metin Balci

Beilstein J. Org. Chem. 2023, 19, 764–770, doi:10.3762/bjoc.19.56

• configurational assignment of organic compounds. The experimental NMR data (13C NMR chemical shifts) are compared with those predicted for all possible theoretical stereoisomers. The correct stereochemistry may be obtained by combining the computed and experimental data [1]. Recently, Novitskiy and Kutateladze

• ]hept-2-ene) at different temperatures and obtained mixtures of the addition products 2–6 (Scheme 1) [4]. The structures of these compounds 2–6 have been elucidated on the basis of 1H and 13C NMR spectral data, as well as a number of 2D techniques (APT, HETCOR and COSY), and extensive double resonance

• elucidated the exact configuration of compound 6. The symmetrical structure of 6 could be characterized easily because of its four-line 13C NMR spectrum. However, on the basis of 13C NMR data alone we were not able to distinguish between possible symmetrical tribromides. The configurations of the bromine

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

• revealed the presence of hydroxy (3429 cm−1) and carbonyl (1733 cm−1) groups. The UV absorption band maximum at λmax 283 nm and five downfield-shifted carbon signals at δC 169.8 (C-16), 163.8 (C-13), 149.3 (C-12), 111.6 (C-11), and 109.6 (C-15) in the 13C NMR data suggested the presence of the α,β

• . The 13C NMR and DEPT spectra, combined with HMQC correlations (Table 1) showed 20 resonances for carbon signals accounting for four methyls, five sp3 methylenes, five methines (two olefinics at δC 111.6, 109.6), and six quaternary carbons (one carbonyl at δC 169.8, two olefinics at δC 163.8, 149.3

• , and one oxygenated sp3 at δC 72.2). The 1H and 13C NMR spectroscopic data of 1 showed great similarity to those of 12α,14β-dihydroxycassa-13(15)-en-12,16-olide (2) isolated from Caesalpinia bonduc [18]. The difference evident was that compound 1 displayed an extended conjugate π-system with an α,β

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• reaction to generate the corresponding multiple Schiff bases and then reduced with sodium borohydride (Scheme 1a). The structure of CS-TPE was characterized by 1H NMR spectra and solid-state CP/MAS 13C NMR spectra, and the results were found to agree with the proposed structure. For instance, the products

• display distinct peaks at δ 7.50–6.70 in their 1H NMR spectra (Figure 1) and at δ 145–120 ppm in their 13C NMR spectra (Figure S1 in Supporting Information File 1), corresponding to the proton resonances of the benzene rings and the carbon resonances of the whole fluorophore, respectively. The appearance

• /MAS 13C NMR spectra of CS-TPE, optical transmittance and concentration-dependent transmittance of CS-TPE, Tyndall effect of CS-TPE and TBTQ-C6/CS-TPE and pH-responsive properties of TBTQ-C6/CS-TPE. Funding We thank the National Natural Science Foundation of China (No. 22061015) and the Hainan High

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

• characterized using spectral methods (for HRMS, 1H, 13C NMR, including 2D techniques, see Supporting Information File 1). To obtain the serine derivative (SerNi)L7, the recently developed electrochemical approach for the stereoselective hydroxyalkylation [32] was used. The reaction protocol is operationally

• (SerNi)L7, see Supporting Information File 1. The serine complex (SerNi)L7 served as the precursor for (ΔAlaNi)L7 which was obtained via dehydration using a commonly used procedure [41]. The new complex (ΔAlaNi)L7 was isolated in 92% yield and fully characterized (HRMS, 1H, 13C NMR, including 2D

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

• , 6.0 Hz, 1H, CH), 3.75 (s, 3H, OCH3), 3.48–3.39 (m, 1H, CH2), 3.36–3.18 (m, 3H, CH2) 2.92 (s, 3H, Phen-CH3), 2.38–2.24 (m, 2H, CH2), 2.22–2.09 (m, 2H, CH2) ppm; 13C NMR (CDCl3) δ 172.4 (Cq), 172.1 (Cq), 158.4 (Cq), 143.7 (Cq), 135.6 (Cq), 135.3 (Cq), 131.8 (CH-Ar), 131. 7 (Cq), 131.5 (Cq), 131.0 (Cq

• –3.47 (m, 1H, CH2-Ala), 2.90 (s, 3H, Phen-CH3) ppm; 13C NMR (CDCl3) δ 172.1 (Cq), 169.5 (Cq), 158.7 (Cq), 135.6 (Cq), 133.1 (Cq), 132.1 (CH-Ar), 131.3 (Cq), 130.7 (Cq), 129.9 (CH-Ar), 129.4 (CH-Ar), 129.1 (CH-Ar), 129.1 (CH-Ar), 128.9 (CH-Ar), 127.4 (CH-Ar), 127.2 (CH-Ar), 126.7 (CH-Ar), 126.6 (CH-Ar

• : Solvents were distilled from appropriate drying agents shortly before use. TLC was carried out on DC-plastikfolien Kieselgel 60 F254 and preparative thick-layer (2 mm) chromatography was done on Merck 60 F254. 1H and 13C NMR spectra were recorded in DMSO-d6 or CDCl3 on Bruker AV 300 and 600 MHz

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• ) were found to be suitable substrates leading to the corresponding products 12h and 12i in 91% and 83% yields, respectively. The use of other directing groups was also suitable for this transformation such as methyl and cyano-substituted pyridines 13a,b, pyrimidine (13c), pyrazole (13d), as well as the

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

• , obtaining white powders with a yield of 99% in each case. The resulting sodium salts of phosphonic acids 9 and 11 were subjected to 1H, 13C, 19F, and 31P NMR spectroscopic analysis as well as mass spectrometry (MS) confirming their purity. The spectroscopic data of 9 and 11 are in agreement with the

• 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

• ) R = -CH2CH(CH3)2; (d) R = -CH(CH3)CH2CH3, (e) R = -CH2Ph; i) (a) 5 or 7 (1 equiv), TMSBr (8 equiv), CH2Cl2, rt, 20 h, (b) MeOH, 30 min.; ii) 8 or 10 (1 equiv), 1 M NaOH (2 equiv), H2O, 15 min. The 13C NMR chemical shifts of C1 and C2 carbon atoms. Inhibitory constants of the studied of α- and β

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• hexane/acetone/MeOH to 20% MeOH. From the six main fractions, three of them showed the new structures, corniculatolide B (9, 3 mg), isocorniculatolide B (10, 2 mg), and corniculatolide C (11, 5 mg), among some other known constituents. Different 1H and 13C NMR and HRESIMS techniques were employed to

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

• complexes and flavonoids were very well classified and discriminated by FTIR–PCA, especially through the type of antioxidant used. However, further synthesis methods and analyses (slow co-crystallization, single-crystal X-ray diffraction, 1H and 13C nuclear magnetic resonance analyses) are needed for the

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• Agilent FTIR spectrophotometer. 1H and 13C NMR spectra were recorded either on an Avance III Bruker or a JEOL JNM-ECS spectrometer at operating frequencies of 200/400/500 MHz (1H) and or 100/125/150 MHz (13C) as indicated in the individual spectra using TMS as an internal standard. Elemental analyses were

• . The multiplicity in the 13C NMR spectra is presented as d for doublet. Experimental procedures General procedure for the synthesis of compounds 1A–E, 2–4C, 5A–E, 6–8C, 9C, 10A, 11A,B, 11E, and 12C as exemplified for (5-(4-fluorophenyl)-1-phenyl-1H-pyrazol-3-yl)(morpholino)methanethione (1C): In a dry

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• kinetic study of the polymerization was monitored by 1H NMR spectroscopy analysis. NMR spectra were recorded on a Fourier 300 spectrometer (1H; 300.12 MHz and 13C (1H); 75.48 MHz; Bruker Biospin; Rheinstetten, Germany) at a temperature of 298 K and evaluated using the MestReNova V.6.0.2.-5475 software

Friedel–Crafts acylation of benzene derivatives in tunable aryl alkyl ionic liquids (TAAILs)

• Swantje Lerch,
• Stefan Fritsch and
• Thomas Strassner

Beilstein J. Org. Chem. 2023, 19, 212–216, doi:10.3762/bjoc.19.20

• procedures, characterization data, copies of 1H and 13C NMR spectra.

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

• Tharun K. Kotammagari,
• Sweta Misra,
• Sayantan Paul,
• Sunita Kunte,
• Rajesh G. Gonnade,
• Manas K. Santra and
• Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

• 5.03 (s, 1H) ppm, respectively. In the 13C NMR, the two carbonyl groups appeared at δ 197.4 and δ 209.4 ppm, and the corresponding two olefinic carbons were observed at δ 135.7 and δ 148.5 ppm. The formation of the dihydroxy compound (±)-4 was also confirmed with a D2O shake experiment. When we added a

• 0 °C (Table 1, entry 7), we obtained the product as a colorless solid (15% yield) after 24 h stirring at room temperature (Scheme 5). The product was characterized as (±)-incarvilleatone (1) by comparison of its 1H NMR and 13C NMR spectra with the reported data [1] of natural (±)-incarvilleatone (1

• enantiomers using single crystal X-ray analysis. Synthesis of (±)-incarviditone (2). Conditions screened for the formation of the (±)-incarvilleatone (1) from (±)-4. Supporting Information Supporting Information File 12: Experimental procedures, biological protocols, 1H and 13C NMR and HRMS spectra, Figures

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

• the 13C NMR spectrum [26] indicates that the interconversion between these conformers is a fast process at room temperature. This is in contrast to the findings for germacrene A (2) and hedycaryol (3) that show strong line broadening in the NMR spectra and multiple sets of peaks for different

• Sharpless epoxidation of its derivative 15-hydroxygermacrene (17) showed that this material was racemic, indicating a rapid interconversion between the enantiomers of 17. Consequently, also the enantiomers of 1 may undergo a fast interconversion [52]. The 1H and 13C NMR data of 1 have been reported [26

• was determined by NMR spectroscopy and verified by the acid-catalysed conversion into δ-selinene (26) (Scheme 9A) [72]. The same compound 18 was also reported from the closely related alga Laurencia nipponica [73] and from lime oil (Citrus aurantifolia) [74]. Fully assigned 1H and 13C NMR data were

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• –Alder reactions. DIA TFA: diisopropylammonium trifluoroacetate. Supporting Information Supporting Information File 8: Numbering scheme, experimental procedures, 1H, 13C and 2D NMR spectra, and mass spectra. Acknowledgements We thank Serdar Dilek for technical assistance and Miguel Vences for fruitful

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

• , 129.1, and 128.9) observed in the 13C NMR spectrum (Table 1), revealing that compound 1 has a linear structure. The 1H NMR spectrum contained resonances typical of an unsaturated fatty acid, such as non-conjugated olefins with four-proton integration (δH ca. 5.34–5.32, 4H), a bisallylic methylene (δH

• only possible structure for compound 1. This assignment was eventually proven after interpretation of the whole set of 1D and 2D NMR data. A carboxy carbon, four sp2 methines, one oxymethine, two oxymethylenes, ten aliphatic methylenes, and a methyl group were collected from the analysis of 13C NMR and

• (3b). 1H (500 MHz) and 13C (125 MHz) NMR data for nostochopcerol (1) in CD3OH (δ in ppm). Antimicrobial activity of nostochopcerol (1) and synthetic analogs. Supporting Information Supporting information features procedures for synthesis of chiral α-linoleoyl glycerols, physicochemical properties of

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• dependence [95]. On the other hand, simple benzyl cations can undergo more controlled (3 + 2) annulations, as is illustrated by the long-known Friedel–Crafts-type acid-catalyzed cascade reaction of styrene leading to the cyclic styrene dimer 86 (Scheme 13c) [96][97]. This (3 + 2) cycloaddition reactivity of

• special ‘pseudoaromatic’ character of the dihydrodithiin ring which has a tendency to remain intact as a conjugated bonding array (cf. chapter 2, also compare to Scheme 13c and 13d). The scope of the dihydrodithiin-based allyl cation cycloadditions can be appreciated by the relative ease with which it

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

• 4.60 (H-17)] and 10 aromatic protons [δH 7.49 (H-6), 7.68 (H-11, H-15), 7.64 (H-12, H-14), 6.90 (H-20, H-24), 7.26 (H-21, H-22, H-23)]. A triplet resonating at δH 7.06 represents the proton located in the difluoromethyl group (H-25), with a 1JHF coupling constant of 53.4 Hz. The 13C NMR spectrum

• ; 1H NMR (800 MHz, CDCl3) δH 2.96 (t, J = 6.6 Hz, 2H, H-18), 4.54 (t, J = 6.6 Hz, 2H, H-17), 6.58 (t, J = 73.5 Hz, 1H, H-16), 6.86 (m, 2H, H-20, H-24), 7.19 (m, 2H, H-12, H-14), 7.22 (m, 1H, H-22), 7.23 (m, 2H, H-21, H-23), 7.37 (s, 1H, H-6), 7.62 (m, 2H, H-11, H-15); 13C NMR (200 MHz, CDCl3) δC 34.5

• , H-6), 7.62 (m, 2H, H-11, H-15); 13C NMR (200 MHz, CDCl3) δC 23.2 (t, J = 26.3 Hz, C-26), 34.5 (C-18), 71.7 (C-17), 106.6 (C-6), 115.6 (t, J = 260.3 Hz, C-16), 118.8 (C-12, C-14), 119.7 (t, J = 241.1 Hz, C-25), 124.7 (C-10), 127.3 (C-22), 128.6 (C-20, C-24), 128.9 (C-21, C-23), 132.6 (C-11, C-15

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• laboratory, King Abd El Aziz University, Jeddah, Saudi Arabia and a Bruker 400 Spectrometer at the Faculty of Pharmacy, Mansoura University, Mansoura, Egypt. The 13C NMR spectra are proton decoupled. IR spectra were recorded on a ATR–Alpha FT–IR Spectrophotometer 400–4000 cm−1 at Taif University, Taif, Saudi

• MHz, CDCl3) δ 5.70 (d, J = 9.6 Hz, 1H, H-4), 5.38–5.34 (m, 1H, H-3), 5.16 (m, 1H, H-6), 1.96–0.76 (m, 26H), 0.73 (s, 3H, CH3-19), 0.69 (d, 3H, J20,21 = 6.4 Hz, CH3-21), 0.65 (d, J = 1.2 Hz, 3H, CH3-26/CH3-27), 0.63 (d, J = 1.6 Hz, 3H, CH3-26/CH3-27), 0.48 (s, 3H, CH3-18); 13C {1H} NMR (150 MHz, CDCl3

• (m, 8H), 1.20–1.08 (m, 9H), 1.06 (s, 3H, CH3-19), 1.04–1.00 (m, 1H), 0.93 (d, J20,21 = 6.4 Hz, 3H, CH3-21), 0.90 (d, J = 1.4 Hz, 3H, CH3-26/CH3-27), 0.88 (d, J = 1.4 Hz, 3H, CH3-26/CH3-27), 0.70 (s, 3H, CH3-18); 13C{1H} NMR (100 MHz, CDCl3) δ 141.5 (C-5), 122.3 (C-6), 57.0, 56.1, 52.6, 50.2, 44.3

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• isomerization. Screening of Lewis acids and hydrogen-bond donors (HBD) for the aza-Nazarov cyclization.a Supporting Information Supporting Information File 165: Experimental procedures, characterization data, and copies of 1H and 13C{1H} NMR spectra. Supporting Information File 166: CIF file of compound 19l

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

• ; stereoisomers; Introduction Calculation of 1H and 13C NMR chemical shifts and coupling constants using density functional theory (DFT) has increasingly become an adjunct to structure determination [1][2][3][4][5][6][7][8]. In particular for complex organic compounds, determination of relative stereochemistry

• at a time. In the same way that improved results are obtainable for both 1H and 13C NMR chemical shifts using scaling methods, calculation of 31P NMR chemical shifts benefit as well from scaling. Chesnut first showed that scaling of the paramagnetic term of chemical shieldings calculated using the

• supported by the amide-like CO infrared stretching frequency of 1654 cm−1. This compound further warrants mention since one might suppose that the carbonyl carbon atom would be found near 170 ppm in the 13C NMR spectrum by analogy to amides, but was instead observed at 228 ppm and confirmed by a calculated