Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• -acetoacetylcoumarin 41, 3-bromoacylpyran 42, and semicarbazide 40 (Scheme 12) [65]. Alternatively, the corresponding chromenes can replace the 3-bromoacylpyrans. A notable advantage of this process is its catalyst-free nature and the achievement of good regioselectivity. Due to the high heterocycle density, this

• reactions in heterocycle synthesis [163][164] and certainly also for substituted pyrazoles. Four classes of 1,3-dipoles are considered as synthetic equivalents for the CN2 synthon: diazo compounds [165], nitrilimines [166], sydnones [167], and azomethinimines [168]. These intermediates undergo (3 + 2

Harnessing the versatility of hydrazones through electrosynthetic oxidative transformations

• Aurélie Claraz

Beilstein J. Org. Chem. 2024, 20, 1988–2004, doi:10.3762/bjoc.20.175

• access to diazo compounds as either synthetic intermediates or products. A special attention is paid to the reaction mechanism with the aim to encourage further development in this field. Keywords: C–H functionalization; diazo compound; electrosynthesis; hydrazone; nitrogen-containing heterocycle

• hydrazones initiated with the SET anodic oxidation of the hydrazone and deprotonation to form the N-centered radical 10. After aza-cyclization on the aromatic ring, a second SET oxidation and deprotonation delivered the heterocycle 9. This mechanism was supported by cyclic voltammetry analysis of a model

• point of view, the authors proposed the formation of N-pyridyl radical 18 through the anodic oxidation of in situ-generated anion 17. Subsequent radical cyclization, second anodic cyclization and deprotonation yielded the fused heterocycle 16. Similarly, Youssef and Alajimi disclosed the electrochemical

Regioselective alkylation of a versatile indazole: Electrophile scope and mechanistic insights from density functional theory calculations

• Pengcheng Lu,
• Luis Juarez,
• Paul A. Wiget,
• Weihe Zhang,
• Krishnan Raman and
• Pravin L. Kotian

Beilstein J. Org. Chem. 2024, 20, 1940–1954, doi:10.3762/bjoc.20.170

• indazoles would provide greater synthetic utility for this valuable heterocycle. These examples suggest a common intermediate such as methyl 5-bromo-1H-indazole-3-carboxylate (6) could be used to generate such compounds. An alkylation strategy that uses the vast array of commercially available alcohols as

Novel oxidative routes to N-arylpyridoindazolium salts

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

Beilstein J. Org. Chem. 2024, 20, 1906–1913, doi:10.3762/bjoc.20.166

• electrode in MeCN solution using Bu4NBF4 as a supporting electrolyte. Oxidation of the salts occurs at high positive potentials (>2 V vs Ag/AgCl, KCl(sat.), Figure 1a), in accordance with the cationic nature of the heterocycle. In the negative potential range, an irreversible peak can be observed in the

Access to 2-oxoazetidine-3-carboxylic acid derivatives via thermal microwave-assisted Wolff rearrangement of 3-diazotetramic acids in the presence of nucleophiles

• Ivan Lyutin,
• Vasilisa Krivovicheva,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 1894–1899, doi:10.3762/bjoc.20.164

• (azetidin-2-one) scaffold to medicinal chemistry and drug design is self-evident. This four-membered heterocycle is a key fragment of many antibiotics [1], including penicillin and its analogues, as well as other pharmacologically important molecules [2]. Therefore, the search for new efficient and

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

• subsequent sections. Influence of heterocycle type In this section, we focus on the character and type of the rings comprising the cc-hPASs, going from the broader perspective (size) to a more detailed view (aromatic/antiaromatic) and finally to the specific type of ring. Size of ring In the broadest sense

• in Supporting Information File 1, section 3.2.). Specific identity of heterocycle The previous analyses revealed two relationships: lower LUMO values were shown to correspond to both the presence of boron-containing rings and to the presence of antiaromatic rings. However, two-thirds of our

• shows scatter plots of the HOMO versus LUMO, each colored according to the presence of a specific type of heterocycle. To avoid ambiguity, only molecules that contain benzene and the heterocycle highlighted in the respective plot are colored (i.e., molecules that contain mixtures of heterocycles are not

Discovery of antimicrobial peptides clostrisin and cellulosin from Clostridium: insights into their structures, co-localized biosynthetic gene clusters, and antibiotic activity

• Moisés Alejandro Alejo Hernandez,
• Katia Pamela Villavicencio Sánchez,
• Rosendo Sánchez Morales,
• Karla Georgina Hernández-Magro Gil,
• David Silverio Moreno-Gutiérrez,
• Eddie Guillermo Sanchez-Rueda,
• Yanet Teresa-Cruz,
• Brian Choi,
• Armando Hernández Garcia,
• Alba Romero-Rodríguez,
• Oscar Juárez,
• Siseth Martínez-Caballero,
• Mario Figueroa and
• Corina-Diana Ceapă

Beilstein J. Org. Chem. 2024, 20, 1800–1816, doi:10.3762/bjoc.20.159

• several precursors, forming superclusters. The RiPPMiner platform [5] was used to predict in silico post-translational modifications of the mature lanthipeptides. Based on these predictions, several clusters did not contain precursor peptides with a predicted lanthipeptide heterocycle formation and were

Ugi bisamides based on pyrrolyl-β-chlorovinylaldehyde and their unusual transformations

• Alexander V. Tsygankov,
• Vladyslav O. Vereshchak,
• Tetiana O. Savluk,
• Serhiy M. Desenko,
• Valeriia V. Ananieva,
• Oleksandr V. Buravov,
• Yana I. Sakhno,
• Svitlana V. Shishkina and
• Valentyn A. Chebanov

Beilstein J. Org. Chem. 2024, 20, 1773–1784, doi:10.3762/bjoc.20.156

• , azomethines based on aromatic amines and substituted pyrrolecarbaldehyde [40] or pyrrolyl-β-chlorovinylaldehyde [39], contain several frequently encountered motifs in drugs and drug candidates – a pyrrole heterocycle and an azomethine C=N fragment (Figure 1) – and exhibit some biological activity. Thus, Ugi

Harnessing unprotected deactivated amines and arylglyoxals in the Ugi reaction for the synthesis of fused complex nitrogen heterocycles

• Javier Gómez-Ayuso,
• Pablo Pertejo,
• Tomás Hermosilla,
• Israel Carreira-Barral,
• Roberto Quesada and
• María García-Valverde

Beilstein J. Org. Chem. 2024, 20, 1758–1766, doi:10.3762/bjoc.20.154

• order to improve the synthesis of this fused heterocycle, different strategies were tried, e.g., performing the Ugi reaction in different solvents (dichloromethane, ethyl acetate, methanol) to prevent the precipitation of benzodiazepine 5c, conducting the Ugi reaction in boiling methanol or treating the

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• predominant. The outlined synthetic procedures emphasize the pivotal steps for constructing the heterocycles, often accompanied by a detailed account of the overall synthesis pathway. The review encompasses innovative compounds, including bis-steroids linked by a spiro heterocycle and steroids conjugated to

• the future design of more potent and selective drugs. Keywords: biological activity; drug development; heterocycle; spiro steroid; synthetic transformations; Introduction Small-ring heterocycles constitute valuable scaffolds in medicinal chemistry for generating biologically active derivatives

• functional groups of the steroid involved in heterocycle formation. Many descriptions also include the parent steroid alongside the total steps required to synthesize the target compound. Furthermore, numerous compounds feature data regarding their biological activity, underscoring the remarkable potential

Oxidation of benzylic alcohols to carbonyls using N-heterocyclic stabilized λ³-iodanes

• Thomas J. Kuczmera,
• Pim Puylaert and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2024, 20, 1677–1683, doi:10.3762/bjoc.20.149

• Thomas J. Kuczmera Pim Puylaert Boris J. Nachtsheim Institute for Organic and Analytical Chemistry, University of Bremen, Bremen, Germany Institute for Inorganic Chemistry and Crystallography, University of Bremen, Bremen, Germany 10.3762/bjoc.20.149 Abstract We present N-heterocycle-stabilized

• the corresponding carboxylic acids [16]. Additives such as bromide salts or Al2O3 can eliminate this problem and allow selective oxidation to some extent [17][18][19][20]. During the past years, N-heterocycle-stabilized iodanes (NHIs) were demonstrated as suitable tools for various applications among

• proved to be effective in a model oxidation reaction of n-octanol (2). Since previous investigations have repeatedly shown that the number of heteroatoms in the N-heterocycle correlates with the NHIs activity, a series of tetrazole- and tetrazine-substituted NHIs 1a–e was synthesized (Figure 2) [29][30

Generation of multimillion chemical space based on the parallel Groebke–Blackburn–Bienaymé reaction

• Evgen V. Govor,
• Vasyl Naumchyk,
• Ihor Nestorak,
• Dmytro S. Radchenko,
• Dmytro Dudenko,
• Yurii S. Moroz,
• Olexiy D. Kachkovsky and
• Oleksandr O. Grygorenko

Beilstein J. Org. Chem. 2024, 20, 1604–1613, doi:10.3762/bjoc.20.143

• reaction is a three-component condensation of an α-amino heterocycle (e.g., 2-aminopyridine) 1, an aldehyde 2, and an isonitrile 3 providing the corresponding fused imidazoles (e.g., imidazo[1,2-a]pyridines) of general formula 4 (Scheme 1) [18][19][20][21]. Imidazo[1,2-a]pyridines and related heterocycles

• }). Some of these results (e.g., on the reactivity of aminopyrimidine derivatives) were in accordance with the previous literature data [21][29]. Meanwhile, electronic effects of the substituents in the amino heterocycle reported in the previous works were somewhat contradictory. Whereas for the NO2 group

Benzylic C(sp³)–H fluorination

• Alexander P. Atkins,
• Alice C. Dean and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 1527–1547, doi:10.3762/bjoc.20.137

• ]. The authors proposed the formation of a charge-transfer complex between the heterocycle and Selectfluor, capable of promoting an ET/PT or PCET pathway to furnish the carbon-centred radical at the heterobenzylic position. Fluorine-atom-transfer with Selectfluor then afforded the desired product

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• (Scheme 2) were obtained in good to excellent yields (71–97%) and enantioselectivities (83.5–98% ee). Molecules containing two or more biologically relevant heterocycle motifs are receiving attention in drug discovery research [31][32][33]. The enantioselective synthesis of such hybrid molecules is

Oxidative hydrolysis of aliphatic bromoalkenes: scope study and reactivity insights

• Amol P. Jadhav and
• Claude Y. Legault

Beilstein J. Org. Chem. 2024, 20, 1286–1291, doi:10.3762/bjoc.20.111

• bromoalkenes as substrates delivering dialkyl α-bromoketones which are highly sought-after synthons in heterocycle synthesis and medicinal chemistry, thus overcoming the limitations of previous methods. The reaction accommodates sterically hindered bromoalkenes as substrates, leading to the corresponding α

The Ugi4CR as effective tool to access promising anticancer isatin-based α-acetamide carboxamide oxindole hybrids

• Carolina S. Marques,
• Aday González-Bakker and
• José M. Padrón

Beilstein J. Org. Chem. 2024, 20, 1213–1220, doi:10.3762/bjoc.20.104

• , 72, 74 and 84% yield, respectively. An exception was noticed for N-heterocycle units (pyridine and 1H-pyrrole) substituted in the same position, since compounds 8g, 8l and 8i were obtained in 56, 51 and 36% yield, respectively. The 1,2,3-triazole hybrid isatin compound 8n was obtained in 56% yield

• . Compounds 5ib and 5hb, with N-Boc protected-heterocycle units in the 5-amide position of the oxindole ring (Scheme 2) failed to afford the corresponding 3-deprotected isatin hybrids, since only decomposition byproducts (not identified) were obtained. Antiproliferative activity Considering the potential

Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer

• Mohd Farhan Ansari,
• Atul Kumar Maurya,
• Abhishek Kumar and
• Saravanakumar Elangovan

Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98

One-pot Ugi-azide and Heck reactions for the synthesis of heterocyclic systems containing tetrazole and 1,2,3,4-tetrahydroisoquinoline

• Jiawei Niu,
• Yuhui Wang,
• Shenghu Yan,
• Yue Zhang,
• Xiaoming Ma,
• Qiang Zhang and
• Wei Zhang

Beilstein J. Org. Chem. 2024, 20, 912–920, doi:10.3762/bjoc.20.81

• ; Introduction Tetrazole is a privileged heterocycle existing in a range of biological and medicinally interesting compounds [1][2] with antifungal [3][4], antibacterial [5], anticancer [6][7], antiparasitic [8], and antihypertensive properties [9] including FDA approved drugs such as valsartan and cefmetazole

• [10][11] (Figure 1). The tetrazole ring can also be found in functional materials for photography, imaging, and military applications [12][13][14][15][16][17]. The hydroisoquinoline core, such as 1,2,3,4-tetrahydroisoquinoline and pyrazino[2,1-a]isoquinolinone, is also a privileged heterocycle which

Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles

• Jun Kikuchi,
• Roi Nakajima and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2024, 20, 891–897, doi:10.3762/bjoc.20.79

• , producing the vicinal N-heterocycle-substituted olefin 9 as a mixture of stereoisomers in 65% yield. Finally, 4aa proved to be a viable nucleophilic VBX for the carboiodanation of 3-methoxybenzyne [35], furnishing the new ortho-alkenylated arylbenziodoxole 10 with exclusive C–C bond formation at the distal

(Bio)isosteres of ortho- and meta-substituted benzenes

• H. Erik Diepers and
• Johannes C. L. Walker

Beilstein J. Org. Chem. 2024, 20, 859–890, doi:10.3762/bjoc.20.78

• potential explanation for these observations is an increase in heterocycle basicity on bioisosteric switch of a neighbouring aromatic group. However, the drug-specific half-maximal rescue concentration (RC50 CFTR, lower indicates higher biological activity), indicative of the biological activity, increased

• was also employed for the synthesis of 1,2,4-BCHs [35]. Heterocycle-substituted BCHs were accessed by [2π + 2σ] photocycloaddition by Glorius and co-workers [79] and Houk, Glorius and co-workers [80]. This reactivity was enabled by triplet energy transfer catalysis activating the heterocyclic

Evaluation of the enantioselectivity of new chiral ligands based on imidazolidin-4-one derivatives

• Jan Bartáček,
• Karel Chlumský,
• Jan Mrkvička,
• Lucie Paloušová,
• Miloš Sedlák and
• Pavel Drabina

Beilstein J. Org. Chem. 2024, 20, 684–691, doi:10.3762/bjoc.20.62

• with reduced efficiency in the absence of a second stereogenic centre at position 5. Nonetheless, IV proved to be an effective enantioselective organocatalyst in the asymmetric aldol reaction, matching the enantioselectivity levels of other proline-heterocycle derivatives [25]. Overall, our findings

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• , amoxapine, an ibrutinib derivative, N-desmethyl sildenafil, silodosin, and lapatinib (4d–k, 35–67%). The late-stage modification of these drug agents and their derivatives in this MCR underlined the synthetic value and high functional group tolerance (e.g., aromatic amine, amide, alcohol, heterocycle). We

Synthesis and biological profile of 2,3-dihydro[1,3]thiazolo[4,5-b]pyridines, a novel class of acyl-ACP thioesterase inhibitors

• Jens Frackenpohl,
• David M. Barber,
• Guido Bojack,
• Birgit Bollenbach-Wahl,
• Ralf Braun,
• Rahel Getachew,
• Sabine Hohmann,
• Kwang-Yoon Ko,
• Karoline Kurowski,
• Bernd Laber,
• Rebecca L. Mattison,
• Thomas Müller,
• Anna M. Reingruber,
• Dirk Schmutzler and
• Andrea Svejda

Beilstein J. Org. Chem. 2024, 20, 540–551, doi:10.3762/bjoc.20.46

• -dihydro[1,3]thiazolo[4,5-b]pyridine; acyl-ACP thioesterase; bioisostere; herbicide; heterocycle; Introduction The presence of weed infestations exerts a high strain on food production around the globe by depleting resources for the crops and facilitating the transmission of diseases [1]. Although

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• . Finally, single electron oxidation of 169 at the anode, followed by rearomatization via proton-transfer forms the alkylated heterocycle 170. As discussed in Scheme 25, the Ni-catalyzed cross-electrophile coupling between redox-active esters and aryl halides requires the addition of a stoichiometric