1-Butyl-3-methylimidazolium tetrafluoroborate as suitable solvent for BF₃: the case of alkyne hydration. Chemistry vs electrochemistry

• Marta David,
• Elisa Galli,
• Richard C. D. Brown,
• Marta Feroci,
• Fabrizio Vetica and
• Martina Bortolami

Beilstein J. Org. Chem. 2023, 19, 1966–1981, doi:10.3762/bjoc.19.147

• -BF4 towards disubstituted alkynes containing a carbonyl group adjacent to the triple bond. This class of substrates, after water addition, yields 1,3-dicarbonyl compounds, which could yield BF2-chelates under our experimental conditions [109]. In order to study their behaviour, we decided to avoid

Non-noble metal-catalyzed cross-dehydrogenation coupling (CDC) involving ether α-C(sp³)–H to construct C–C bonds

• Hui Yu and
• Feng Xu

Beilstein J. Org. Chem. 2023, 19, 1259–1288, doi:10.3762/bjoc.19.94

• tricyclic chromane nucleus from 8-hydroxyisochromanes and 1,3-dicarbonyl compounds in the presence of Cu(OTf)2 and T+BF4− (Scheme 7b) [57]. The strategy has a wide range of applications and is highly diastereoselective, making it an attractive strategy for synthesizing related natural products. The role of

• copper is to activate the 1,3-dicarbonyl compounds through complexation that leads to a highly diastereoselective nucleophilic addition. Scheidt et al. reported an enantioselective Cu-catalyzed intramolecular cross-dehydrogenative coupling approach to substituted tetrahydropyrans with excellent yields

• -dicarbonyl compounds. Rare earth-metal-catalyzed CDC reaction. Visible-light-driven CDC of cycloalkanes with benzazoles. Photoinduced alkylation of quinoline with cyclic ethers. Photocatalyzed CDC reactions between α-C(sp3)–H bonds of ethers and C(sp2)–H bonds of aromatics.

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

• nitronic acid furnishes cyclopropane 1a (method a) [1][4][12][13]. Halogenated malonate 6a [7][14][15][16][17] and nitrostyrene 7 [18] can also be used as substrates in this protocol (methods b and c, respectively). In these methods, diesters are mostly used as 1,3-dicarbonyl compounds, with acetylacetone

• quite difficult, although they would be very useful in synthetic chemistry, if available. In this study, we investigated the synthesis of nitrocyclopropanes using keto esters 3c–f and diketones 3b and 3g instead of diester 3a as the starting 1,3-dicarbonyl compounds. Results and Discussion We commenced

• ), 133.8 (CH), 135.1 (C), 137.8 (C), 167.0 (C), 192.7 (C). Although the adduct was obtained as a mixture of diastereomeric isomers (54:46), these isomers were subjected to subsequent cyclization without separation. When other 1,3-dicarbonyl compounds 3 or nitrostyrene 2b were used, the reaction was

Facile access to 3-sulfonylquinolines via Knoevenagel condensation/aza-Wittig reaction cascade involving ortho-azidobenzaldehydes and β-ketosulfonamides and sulfones

• Ksenia Malkova,
• Andrey Bubyrev,
• Stanislav Kalinin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 800–807, doi:10.3762/bjoc.19.60

• , the method for the synthesis of 3-acyl-substituted quinolines from o-azidobenzaldehydes and 1,3-dicarbonyl compounds was reported [70][71] (Figure 2a). A combination of Knoevenagel condensation and aza-Wittig reaction allowed to build up target products in high yields. In case of [70], the procedure

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• presented in Scheme 31 [136]. An enantioselective oxidation can be achieved by combining a ketone catalyst with a chiral amine [137]. The resulting chiral oxaziridine intermediate promotes the hydroxylation of CH-acidic 1,3-dicarbonyl compounds in high yields and enantioselectivities (up to 99% ee) (Scheme

Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates

• Péter Kisszékelyi,
• Tibor Peňaška,
• Klára Stankovianska,
• Mária Mečiarová and
• Radovan Šebesta

Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124

• 1,3-dicarbonyl compounds using a catalytic amount of hydrazine hydrate without solvent in a short reaction time (10 min) [14]. Reactions of 2-aminothiophenols with β-keto esters and β-diketones under microwave irradiation (MWI) using basic alumina as heterogeneous catalyst without solvent afforded 4H

• -benzo-1,4-thiazines in a yield of 69–85% within 6–11 min [15]. Furthermore, baker’s yeast as whole-cell biocatalyst catalyzed the reaction of 2-aminothiophenols with 1,3-dicarbonyl compounds in methanol and the corresponding 4H-benzo-1,4-thiazines were prepared in 51–82% yield. These reactions were

• significantly accelerated by ultrasonic irradiation [16]. Cyclocondensation of 1,3-dicarbonyl compounds with substituted diaryl disulfides in water in the presence of β-cyclodextrin gave 2,3-disubstituted benzo-1,4-thiazines in 70–91% yield in 50 min [17]. A highly efficient visible-light-mediated one-pot

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• and 1,3-dicarbonyl compounds 84 via synergistic photoredox/iron catalysis (Scheme 14) [90]. This protocol parallels Li’s seminal report in 2007 [44]; however, under these reaction conditions, the reactive radical was propagated across an alkene before termination with the activated methylene unit

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• synthesize tetrahydrobenzo[a]xanthene-11-ones 184 and diazabenzo[a]anthracene-9,11-dione derivatives 185 in good yields via a multicomponent reaction (Scheme 42) [76]. This methodology was based on the cyclocondensation of aromatic aldehydes 180, β-naphthol (181), and cyclic 1,3-dicarbonyl compounds 182 or

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• addition of cyclic 1,3‐dicarbonyl compounds, including 4-hydroxycoumarins 1, to α,β‐unsaturated enones 2 (Scheme 1). This versatile Michael reaction afforded (S)-warfarin (3a) and other Michael adducts 3 in high yields and good enantiomeric excess (ee), using (4S,5S)-4,5-diphenylimidazolidine-2-carboxylic

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• ], electron-rich alkenes (entry 3) [65][66], alkyl sulfides (entry 4) [65][67], 1,3-dicarbonyl compounds [65][68], phosphonate esters (entry 5) [65], steroidal silyl enol ethers and enol acetates (entry 6) [65], pyrimidine bases and nucleosides (entry 7) [67][69], phenylalkynes (entry 8) [70], anthraquinones

• -dicarbonyl compounds using Selectfluor (16-3a) [61]. In 1995, the same group reported that Selectfluor reacted with quinuclidine to form N-fluoroquinuclidinium tetrafluoroborate in quantitative yield [62] (Scheme 35). They described this as a “transfer fluorination” since there was an intermolecular transfer

• , Grignard reagents, and aromatic compounds under mild conditions. In each case Selectfluor gave the corresponding fluorinated products in good to high yields (Scheme 34). As can be seen in Figure 3 and Figure 4, two years later (1994), Banks et al. reported mono- and difluorinations of various 1,3

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• compounds 9. The proposed mechanism for the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles 11 from the reaction of primary amines 10 with 1,3-dicarbonyl compounds 9. Synthesis of fully decorated 1,2,3-triazoles 19 containing a sulfur-based side chain. Mechanism for the formation of fully decorated 1,2,3

• aniline (Scheme 5) [40]. A one-pot and multicomponent route to 1,4,5-trisubstituted 1,2,3-triazoles 11 containing a carboxylic ester group on the triazole ring was reported by Zhao et al. This strategy generates desired products from the reaction of readily available primary amines 10, 1,3-dicarbonyl

• 8 from the reaction of aryl azides 7 with enaminones 6. Proposed mechanism for the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles from the reaction of aryl azides with enaminones. Synthesis of 1,4,5-trisubstituted 1,2,3-triazoles 11 from the reaction of primary amines 10 with 1,3-dicarbonyl

Synthesis of β-triazolylenones via metal-free desulfonylative alkylation of N-tosyl-1,2,3-triazoles

• Soumyaranjan Pati,
• Renata G. Almeida,
• Eufrânio N. da Silva Júnior and
• Irishi N. N. Namboothiri

Beilstein J. Org. Chem. 2021, 17, 762–770, doi:10.3762/bjoc.17.66

• compounds as binucleophiles for the construction of various carbocycles, heterocycles as well as in asymmetric catalysis [44][45][46][47][48][49][50]. Our initial objective to trap the aza vinyl rhodium carbenoid using 1,3-dicarbonyl compounds to form pyrazolone was unsuccessful which instead led to the

• formation of an unexpected product, i.e., β-triazolylenone. Being inspired by the results, we intended to use 1,3-dicarbonyl compounds as detosylative alkylating agents that would lead to the formation of β-triazolylenones in a highly regioselective manner under mild conditions (Scheme 1d). Results and

• (55%) yield. Unfortunately, the reaction was not successful with dimedone (2d), 1,3-indanedione (2e) and acyclic 1,3-dicarbonyl compounds such as acetylacetone (2e) and ethyl acetoacetate (2f). The structure and regiochemistry of all the products were confirmed by detailed analysis of their spectral

Selective synthesis of α-organylthio esters and α-organylthio ketones from β-keto esters and sodium S-organyl sulfurothioates under basic conditions

• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Thiago Barcellos,
• Claudio C. Silveira and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2021, 17, 234–244, doi:10.3762/bjoc.17.24

• , and related compounds. Some of them are catalyzed by expensive transition metals, such as gold, iridium, palladium, and titanium. More recently, the selective formation of C–S bonds using 1,3-dicarbonyl compounds, followed by a C–C bond cleavage has emerged as a versatile and less expensive protocol

• to α-sulfenylated amides (Scheme 1C) [52]. Inspired by those elegant pioneering studies, we explored the reaction of 1,3-dicarbonyl compounds with Bunte salts mediated by a base (Scheme 1D). The choice of NaOH as the base and its concentration were crucial to the selective synthesis of α-thio esters

• of α-thiocarbonyl compounds by C–C bond cleavage of 1,3-dicarbonyl compounds. Formation of the enol 6 from acetylacetone (5). Formation of thio-substituted keto–enol tautomers 7 and 8. Proposed mechanism for the synthesis of 3. A tentative pathway for the synthesis of 4. Optimization of the reaction

Three-component reactions of aromatic amines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal to access N-(hetero)aryl-4,5-unsubstituted pyrroles

• Wenbo Huang,
• Kaimei Wang,
• Ping Liu,
• Minghao Li,
• Shaoyong Ke and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2920–2928, doi:10.3762/bjoc.16.241

• , School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu road, Hongshan District, Wuhan 430074, China 10.3762/bjoc.16.241 Abstract N-(Hetero)aryl-4,5-unsubstituted pyrroles were synthesized from (hetero)arylamines, 1,3-dicarbonyl compounds, and α

• investigated under the optimized reaction conditions. The substrate scope of the 1,3-dicarbonyl component was first examined (Scheme 2). Acetylacetone reacted smoothly with 1a and 2a to form 4b in 52% yield. 1,3-Dicarbonyl compounds bearing an ester group readily participated in this reaction, affording the

• acetal (2a) and 1,3-dicarbonyl compounds was developed by using AlCl3 as a catalyst. The developed chemistry is also successful for the synthesis of functionalized pyrazolo[3,4-b]pyridine derivatives. This study offered a complementary method to construct pyrrole scaffolds through [1 + 2 + 2] annulation

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• of the aromatic S–S bond by visible light. In 2019, Meng and co-workers reported a visible light-mediated disulfide-catalyzed metal-free and base-free α-functionalization of 1,3-dicarbonyl compounds [17]. Under visible-light irradiation, the α-hydroxylation or α-hydroxymethylation of 1,3-dicarbonyl

• expansion of vinyl spiro epoxides. Disulfide-catalyzed aerobic oxidation of diarylacetylene. Disulfide-catalyzed aerobic photooxidative cleavage of olefins. Disulfide-catalyzed aerobic oxidation of 1,3-dicarbonyl compounds. Proposed mechanism of the disulfide-catalyzed aerobic oxidation of 1,3-dicarbonyl

• compounds, was efficiently implemented via this disulfide, which induced an aerobic oxidation. The hydroxylation and hydroxymethylation of a broad range of β-keto esters and β-keto amides that had electron-donating or -withdrawing groups on the phenyl ring gave good to excellent yields (42–98%, Scheme 10

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• oxidizing agent serves to generate oxime radicals from oximes and perform one-electron oxidation of 1,3-dicarbonyl compounds 45. The formation of oxime radicals under the reaction conditions was confirmed by EPR spectroscopy [46]. 1,3-Diketones and 1,3-ketoesters with easily oxidizable groups, such as allyl

• Kharash peroxidation of 1,3-dicarbonyl compounds [88][89][90][91][92][93] did not occur, and a selective formation of the C–O product with oximes was observed. Benzylmalononitrile (47) was introduced into the oxidative C–O coupling with diacetyl oxime (19) analogously to 1,3-dicarbonyl compounds [46], but

• , including oximes, was demonstrated [44]. In contrast to the cross-dehydrogenative coupling of oximes with 1,3-dicarbonyl compounds, both one-electron oxidants (Fe(ClO4)3, (NH4)2Ce(NO3)6) and two-electron oxidants (PhI(OAc)2, Pb(OAc)4), that vary greatly in properties, are applicable for this process. After

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• be isolated in 30% yield, while the aniline derivative was not formed (Scheme 3). There are only a few known methods for the synthesis of this kind of 1H-pyridines. In a cyclocondensation, starting from 1,3-dicarbonyl compounds, Elnagdi and co-workers synthesized 1H-pyridines with an additional cyano

In water multicomponent synthesis of low-molecular-mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines

• Irina G. Tkachenko,
• Sergey A. Komykhov,
• Vladimir I. Musatov,
• Svitlana V. Shishkina,
• Viktoriya V. Dyakonenko,
• Vladimir N. Shvets,
• Mikhail V. Diachkov,
• Valentyn A. Chebanov and
• Sergey M. Desenko

Beilstein J. Org. Chem. 2019, 15, 2390–2397, doi:10.3762/bjoc.15.231

• was assayed with 1,1-diphenyl-2-picrylhydrazyl. Keywords: 5-aminotetrazole; antioxidant activity; 1,3-dicarbonyl compounds; multicomponent synthesis; tetrazolo[1,5-a]pyrimidines; Introduction Tetrazolo[1,5-a]pyrimidines and their partially hydrogenated derivatives are known for their interesting

• promising for further detailed studies. Conclusion The three-component method which is based on the in-water reaction of 5-aminotetrazole with 1,3-dicarbonyl compounds and aliphatic aldehydes, like formaldehyde or acetaldehyde, under microwave activation, was applied for the preparation of low-molecular

• -mass 4,7-dihydrotetrazolo[1,5-a]pyrimidines. The use of acetoacetic ester derivatives as 1,3-dicarbonyl compounds in the reaction showed high selectivity under catalyst-free conditions, whereas in the case of acetylacetone the formation of a side product was observed. The desired product could be

Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones

• Alexander N. Reznikov,
• Anastasiya E. Sibiryakova,
• Marat R. Baimuratov,
• Eugene V. Golovin,
• Victor B. Rybakov and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127

• ) complexes as catalyst for the Michael addition of 1,3-dicarbonyl compounds to nitroalkenes [47][48][49][50][51][52][53][54]. This reaction was used as a key stage in the synthesis of non-racemic analogues of GABA and substituted pyrrolidinones with neurotropic activity [47][51][52][54]. It should be noted

• proposed mechanism for 1,3-dicarbonyl compounds [47] to explain how Ni catalysts are able to activate the substrates. The postulated catalytic cycle is summarized in Scheme 1. We assume that the β-ketosulfone coordinates to the Ni complex generating Ni-enolate B. The nitroalkene is activated by

• coordination to Ni. The complex B regenerates after the conjugate addition via transition state C and coordination of a new β-ketosulfone molecule to Ni. TS1 and TS2 are proposed by analogy with 1,3-dicarbonyl compounds [47] to rationalize the asymmetric induction. As illustrated in Scheme 2, β-ketosulfone is

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• - and meta-substituted anilines 2 did not produce isoindolinones 32, and aliphatic amines only reacted when p-toluenesulfonic acid was present. The reaction has also been applied to 1,3-dicarbonyl compounds, however, only residual amounts of isoindolinones 32 were detected and deamination products

• can intramolecularly attack the ester function, giving rise to lactam 32. As pointed out above, unfortunately this methodology did not work properly when it was first applied to 1,3-dicarbonyl compounds. Nevertheless, more recently, two research groups have disclosed, nearly simultaneously, the three

• -component cyclization of 2-formylbenzoic acids, primary amines and a 1,3-dicarbonyl compounds. The first proposal uses 2-formylbenzoic acid 33 (R = H, conditions A, Scheme 9), cyclic aliphatic and aromatic diketones 34 such as dimedone (R2R3 = -CH2CMe2CH2-) as the 1,3-dicarbonyl partner and a variety of

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• another molecule Mn(OAc)3 [48]. Later, Shi et al. demonstrated an oxidative annulation of MCPs 1 with 1,3-dicarbonyl compounds 7 using manganese(III) catalysis under room temperature conditions, which afforded 4,5-dihydrofuran derivatives 8 as [3 + 2] annulation products (cyclopropyl retained adducts) in

• oxidative radical ring-opening/cyclization of cyclopropane derivatives. Mn(OAc)3-mediated oxidative radical ring-opening and cyclization of MCPs with malonates. Mn(III)-mediated oxidative radical ring-opening and cyclization of MCPs with 1,3-dicarbonyl compounds. Heat-promoted ring-opening/cyclization of

DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• -dicarbonyl compounds, and ammonium acetate promoted by acid under aerobic conditions [37][38]. Furthermore, Brønsted- and Lewis-acid-catalyzed cyclization reactions between β-enamino esters (derived from β-ketoesters and ammonium acetate) and alkynones/α,β-unsaturated carbonyls/in situ generated α,β

• construction of pyridines bearing a carboxylate or CN group at C3 position has been a lucrative target for chemists due to the pharmaceutically privileged status (Figure 1). In this context, Rodriguez’s group successfully established a one-pot three-component reaction between β,γ-unsaturated α-ketoesters, 1,3

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• another published article by this research group, silica-supported sulfonated 1,4-diazabicyclo[2.2.2]octane 71 was used for the one-pot tandem Knoevenagel–Michael cyclization reaction between isatin derivatives 32 or acenaphthenquinone (33), barbituric acid derivatives 73, and 1,3-dicarbonyl compounds 20

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• . Results and Discussion The starting diazocyclopentanediones (DDK, 1a–f) were synthesized from the corresponding 1,3-dicarbonyl compounds [31][32][33] employing a diazotransfer reaction [34][35][36][37][38][39]. Diazocyclopentenedione 1g was prepared by thermal cycloelimination from diazodiketones 1d,e [38