Natural resorcylic lactones derived from alternariol

• Joachim Podlech

Beilstein J. Org. Chem. 2024, 20, 2171–2207, doi:10.3762/bjoc.20.187

Computational toolbox for the analysis of protein–glycan interactions

• Ferran Nieto-Fabregat,
• Maria Pia Lenza,
• Angela Marseglia,
• Cristina Di Carluccio,
• Antonio Molinaro,
• Alba Silipo and
• Roberta Marchetti

Beilstein J. Org. Chem. 2024, 20, 2084–2107, doi:10.3762/bjoc.20.180

• of different and particular structures [7][8]. Additionally, glycans can adopt a wide variety of different shapes; five-membered ring sugars can exhibit envelope and twist conformations usually represented on a pseudo-rotational wheel; while six-membered ring structures can adopt chair (C), boat (B

Electrochemical radical cation aza-Wacker cyclizations

• Sota Adachi and
• Yohei Okada

Beilstein J. Org. Chem. 2024, 20, 1900–1905, doi:10.3762/bjoc.20.165

• the difference in such reactivities are intramolecular cyclizations (Scheme 1). A radical cyclization generates a five-membered ring with a less-stable primary radical, while a six-membered ring with a secondary cation is obtained through ionic cyclization. When such intramolecular cyclizations are

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Hetero-polycyclic aromatic systems: A data-driven investigation of structure–property relationships

• Sabyasachi Chakraborty,
• Eduardo Mayo Yanes and
• Renana Gershoni-Poranne

Beilstein J. Org. Chem. 2024, 20, 1817–1830, doi:10.3762/bjoc.20.160

• pronounced for pyrazine than pyridine). Conversely, the five-membered ring (pyrrole) shifts it to the right and upwards, maintaining a similar HOMO range to COMPAS-1, but extending into much higher LUMO values. The behavior of the various N-containing rings is well documented in the literature [17][44][45

Regio- and stereochemical stability induced by anomeric and gauche effects in difluorinated pyrrolidines

• Ana Flávia Candida Silva,
• Francisco A. Martins and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2024, 20, 1572–1579, doi:10.3762/bjoc.20.140

• were degenerate (i.e., 10/11 and 14/15), reducing the number of distinct structures to 22. However, due to the considerable flexibility of the five-membered ring and the low barrier for pyramidal interconversion of the N–H moiety, some inputs converged to the same isomer post-geometry optimization

Synthesis of indano[60]fullerene thioketone and its application in organic solar cells

• Yong-Chang Zhai,
• Shimon Oiwa,
• Shinobu Aoyagi,
• Shohei Ohno,
• Tsubasa Mikie,
• Jun-Zhuo Wang,
• Hirofumi Amada,
• Koki Yamanaka,
• Kazuhira Miwa,
• Naoyuki Imai,
• Takeshi Igarashi,
• Itaru Osaka and
• Yutaka Matsuo

Beilstein J. Org. Chem. 2024, 20, 1270–1277, doi:10.3762/bjoc.20.109

• , however, the carbonyl group in FIDO showed a strong in-plane stretching vibration as shown in Figure S1 (Supporting Information File 1). Due to the direct connection between the five-membered ring and the fullerene cage, the out of plane bending vibration was easily affected by the fullerene cage

Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

• Naziha Tarannam,
• Prashant Kumar Gupta,
• Shani Zev and
• Dan Thomas Major

Beilstein J. Org. Chem. 2024, 20, 1189–1197, doi:10.3762/bjoc.20.101

• seven-membered ring and the remaining four 5-7 bicyclic compounds with the carbocation on the five-membered ring. The variations in energy within the groups of carbocations (i.e., 6-6 and two kinds of 5-7 bicyclic carbocations) can be ascribed to intramolecular repulsion interactions, as seen from non

• 6-6 bicyclic rings, four 5-7 bicyclic compounds with the carbocation located on the seven-membered ring and the remaining four 5-7 bicyclic compounds with the carbocation on the five-membered ring. 4-8 Bicyclic rings were not considered. Similar to germacrene, the hedycaryol carbocations can also be

• bicyclic compounds with the carbocation on the five-membered ring. The variations in energy within the groups of carbocations (i.e., 6-6 and two kinds of 5-7 bicyclic carbocations) can be ascribed to intramolecular repulsion interactions, as seen from NCI plots. Overall, the 6-6 bicyclic carbocations were

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• ] and the broad spectrum of biological activities. Among the five-membered ring compounds, we find indanone (1, Figure 1). Within the class of indanones, we can highlight some interesting compounds. For example, nakiterpiosinone (2), which inhibits the growth of P388 mouse leukemia cells with an average

A Diels–Alder probe for discovery of natural products containing furan moieties

• Alyssa S. Eggly,
• Namuunzul Otgontseren,
• Carson B. Roberts,
• Amir Y. Alwali,
• Haylie E. Hennigan and
• Elizabeth I. Parkinson

Beilstein J. Org. Chem. 2024, 20, 1001–1010, doi:10.3762/bjoc.20.88

• strategy has been previously used in probe development [9][16][17], no one has reported it previously with furans. This is likely because utilizing a furan ring as the diene source can be quite challenging. Furans are aromatic molecules, resulting in these five-membered ring systems being relatively

Chemical and biosynthetic potential of Penicillium shentong XL-F41

• Ran Zou,
• Xin Li,
• Xiaochen Chen,
• Yue-Wei Guo and
• Baofu Xu

Beilstein J. Org. Chem. 2024, 20, 597–606, doi:10.3762/bjoc.20.52

• gene cluster for compounds 1 and 2, highlighting ShnA, ShnB, ShnC, ShnD, and ShnE as core genes. B: The diagram proposes biosynthetic pathways for compounds 1 and 2, detailing three potential mechanisms that could convert the five-membered ring structure of compound 2 into the six-membered ring

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• compound is shown below, in which the hydrogen atoms are omitted for clarity. Atoms are colored grey (carbon), white (hydrogen), brown (bromine), pale-yellow (silicon). Labels of bonds within five-membered ring. Synthesis of IF-DTF ketones 9–12 and dimer 13. Further functionalization of the IF-DTF ketone

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• localized; indeed DFT calculations for the Y = alkyl 1e• derivative indicate spin density almost entirely on the 2-position of the five-membered ring, while for Y = aryl and metallocenyl examples 1b•, 1c•, and 1d• there is substantial spin delocalization onto the Y-substituents [14][55]. Different extents

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• structure of an NHC (8) is shown in Figure 1. NHCs having three nitrogen atoms in the five-membered ring, e.g., 1,2,4-triazolylidenes have also been prepared [6]. Both kinetic as well as thermodynamic effects contribute to the remarkable stability of the NHC ring. The presence of bulky substituent groups on

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• ). These structural features enable the construction of a five-membered ring upon treatment with alkenes [9], diazo compounds (reaction g) [10], and nitriles [11]. Several approaches are available for the synthesis of cyclopropanedicarboxylates 1a, which consist of three steps: 1) conjugate addition, 2

• proceeded, to produce furan 13 with a 46% yield (Scheme 6). The coordination of two carbonyl groups to the tin species facilitated the ring opening of the cyclopropane ring to afford betaine [7], then the oxygen atom of the enolate attacked the benzyl cation to construct a five-membered ring. The subsequent

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

• standing out. The first one (strategy 1, Figure 3) consists in the successive formation of the eight-membered ring B followed by construction of the five-membered ring C: i.e., the cyclooctene ring is built first from a suitably substituted cyclopentane substrate, which then serves as a precursor for the

Characterization of a new fusicoccane-type diterpene synthase and an associated P450 enzyme

• Jia-Hua Huang,
• Jian-Ming Lv,
• Liang-Yan Xiao,
• Qian Xu,
• Fu-Long Lin,
• Gao-Qian Wang,
• Guo-Dong Chen,
• Sheng-Ying Qin,
• Dan Hu and
• Hao Gao

Beilstein J. Org. Chem. 2022, 18, 1396–1402, doi:10.3762/bjoc.18.144

• chemical shifts were performed, which enabled us to determine that C18 and H10 are located on opposite sides of the five-membered ring (Supporting Information File 1, Figures S9 and S10). The conclusion was in agreement with NOE correlations between H10 and Ha12, and between H318 and Hb12 (Supporting

Dienophilic reactivity of 2-phosphaindolizines: a conceptual DFT investigation

• Nosheen Beig,
• Aarti Peswani and
• Raj Kumar Bansal

Beilstein J. Org. Chem. 2022, 18, 1217–1224, doi:10.3762/bjoc.18.127

• dienophiles and undergo Diels–Alder reactions with 1,3-dienes. However, the dienophilic reactivity is affected by the nature of the substituent groups on the two sides of the σ2,λ3-P atom and also by the presence of more nitrogen atom(s) in the five-membered ring. The conceptual density functional theory (DFT

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

• dominant reaction product formed in the reductive opening of the cyclopropane ring in complex 3 was new derivative 5 containing a five-membered ring (see below and Scheme 2). Intramolecular cyclization The anionic species formed in the ring opening in complex 3 undergo fast intramolecular cyclization via

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• NMR spectrum of 4c in CDCl3 showed sharp peaks at 29.21 ppm and 194.61 ppm representing the two carbon atoms of the acetyl group attached to the 4-postion of the heterocyclic five-membered ring. Therefore, the broadening of peaks observed in the 13C NMR spectra is due to the tautomerism of compounds

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

• molecules of phenylpyruvic acid (7) undergo direct condensation to form a five-membered ring intermediate or (path b) polyporic acid (8) undergoes oxidative ring contraction or conversion to generate the cyclopentenone skeleton. To verify which pathway was responsible for the biosynthesis of daturamycins in

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

• interesting to observe that nanospheres with a very low local gold concentration could not catalyze the reaction at all. Actually, product formation was observed only with nanospheres having a higher 30/31 ratio (>6:18). Surprisingly, only the formation of the five-membered ring product 35 was observed, with

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

• indole derivative 31 in 82% yield (Scheme 11) [22]. Being a kinetically very active catalyst, Rh2(OAc)4 favored the formation of the five-membered ring. On the other hand, employment of Pd(OAc)2-catalysis switched the regioselectivity of this C–H insertion reaction. More specifically, under Pd(OAc)2

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• -trig interactions of both the enol nucleophile and the ketone in the transient intermediate 21 bring about formation of the new five-membered ring intermediate 22. Finally, acid-induced dehydration of 22 completes the formation of the pyrrole ring, resulting in conversion into the dihydropyrrolizine

• (74%) and 26c (65%). The reaction times were 1 and 3 hours, respectively. Unexpectedly, the electronic rate dependence that was observed for the five-membered ring enaminones (where electron-withdrawing substituents caused faster cyclization) was reversed for these six-membered systems. At this stage

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• in a diastereomeric pair of cyclized products 69 and 71, respectively. It was observed that the cis-isomer was predominant in the case of the five-membered ring while the trans-isomer was predominant in the case of the six-membered ring formation (Scheme 24) [72]. Cyclization involving alkynes (-C≡C