Organocatalytic kinetic resolution of 1,5-dicarbonyl compounds through a retro-Michael reaction

• James Guevara-Pulido,
• Fernando González-Pérez,
• José M. Andrés and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2025, 21, 473–482, doi:10.3762/bjoc.21.34

• compounds are better leaving groups than diesters or nitro derivatives in this type of transformation. Another possible explanation is that Michael adducts other than 1,5-dicarbonyl compounds require more robust bases to shift the equilibrium toward the retro-Michael product. It is essential to highlight

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

• Anastasiya V. Agafonova,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

• single-crystal X-ray diffraction analysis. The reaction of azetidine with diacyl chloride 2a gave a complex mixture of products, and O-methyl hydroxylamine did not react. Diacyl chloride 2a reacts with methanol and ethanol to give diesters 11a,b (Scheme 5). An experiment with isoxazole 1a and methanol on

Recent advances in transition-metal-free arylation reactions involving hypervalent iodine salts

• Ritu Mamgain,
• Kokila Sakthivel and
• Fateh V. Singh

Beilstein J. Org. Chem. 2024, 20, 2891–2920, doi:10.3762/bjoc.20.243

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• attention. The controlled formation of C–C and C–X bonds in a stereoselective fashion has found extensive application in asymmetric synthesis. Notably, the addition of malonates has attracted significant interest, albeit primarily limited to methyl or ethyl diesters [18][19][20]. The combination of iminium

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

• applied to synthesize 3,4,5-substituted pyrazoles 173 and 174 via 1,3-dipolar cycloaddition of in situ generated diazo compounds and vinylidenecyclopropane diesters 172, which are synthetic equivalents of alkynes (Scheme 58) [176]. Notably, employing aromatic vinylidenecyclopropane diesters (R2 = aryl) in

• the method regioisomers 174 are selectively formed, while unsubstituted diesters (R2 = H) lead to pyrazoles 173 and 174 in a 1:2 ratio. The aforementioned method can be varied by generating β-diazoketones 176 from arylglyoxals and tosylhydrazine, thus making pyrazole 5-carboxylates accessible. Shu et

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

• indenofluorene (IF) or fluorene cores and containing various dithiafulvene (DTF) donor units that gain aromaticity upon oxidation and a variety of acceptor units, such as vinylic diesters, enediynes, and cross-conjugated radiaannulenes (RAs) that gain aromaticity upon reduction. In some cases, the DTF units are

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

• ][48][49][50]: 1) CuII → CuI → CuII; 2) CuI → CuIII → CuI; 3) CuII → CuIII → CuI → CuII. In 2006, Li et al. demonstrated that the CDC reaction of the C(sp3)–H bond of malonate diesters or other active methylene compounds with the C(sp3)–H bond adjacent to the oxygen atom of cyclic and open-chain

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

Design, synthesis, and evaluation of chiral thiophosphorus acids as organocatalysts

• Karen R. Winters and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2022, 18, 1471–1478, doi:10.3762/bjoc.18.154

• a chiral pocket or environment for enantioselective transformations within the proximity of the acidic proton and phosphoryl oxygen. Additionally, the choice of phosphoric acid diesters also provides a bifunctional catalyst containing both an acidic and basic site (Figure 1). Despite the proven

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• -diketo esters 2 (Scheme 1). On the other hand, two carboxylic acid functionalities adjacent to a keto group result in mesoxalic diesters 3, or mesoxalic ester amides 4. The increased electrophilicity of the keto group and the high density of these complex functional groups make such structures attractive

• diesters and ester amides as key intermediates (+)-Awajanomycin Diethyl mesoxalate (90a) is a valuable building block due to the high density of carbon atoms in high oxidation states. As a vic-tricarbonyl compound, its central keto group is an especially potent electrophile. The Koert group used this

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

• /water in the first step and trimethylamine in the next reaction step [56]. Other procedures In 2008, Lin et al. reported a homo-elongation protocol to obtain acene diesters and dinitriles starting from dialdehydes (Scheme 23) [57]. This methodology was based on a Wittig reaction between substituted [n

• ]acene-2,3-dicarbaldehydes 91 and the Wittig reagents 92; DBU was employed to produce the corresponding substituted [n+1]acene-2,3-diethyl diesters 93. Then, in two steps (reduction and Swern oxidation), the authors converted the diesters 93 to the dialdehydes 94, which could be transformed into the

• corresponding [n+2]acene-2,3-diethyl diesters 95 by the procedure described above. The scope of the reaction included five examples of substituted anthracene-2,3-dicarboxylates bearing Cl or alkoxy groups (43–86% yield). Lin et al. also applied the same approach to synthesize acene-2,3-dinitriles 96 by using

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

• reactions, amino diesters 89 being isolated as single diastereoisomers (Scheme 27). Removal of the sulfinyl group under acidic conditions, and further treatment of the resulting ammonium salts with sodium ethoxide, yielded α-methylene-γ-butyrolactams 90, in a one-pot, two-step process [103]. A six-membered

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• are the reduction of prochiral ketones to chiral secondary alcohols, transamination of prochiral ketones to chiral amines, hydrolysis of symmetrical diesters to a chiral monoester, and esterification of prochiral diacids or diols. In desymmetrisation reactions, the enzyme initially produces the two

• ” kinetics This mechanism will be found for reactions of prochiral diacids using most lipases and esterases: either in the hydrolysis of their diesters, or the synthesis of a monoester from the free acid. Because this kinetic mechanism has different reactions for the two enantiomers at every stage, there are

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• dimethoxymethanofullerene 7. Synthesis of fullerene monoesters and symmetric diesters 8–10 and 11–12, respectively. The synthetic route to the first fullerene–peptide conjugate 16. Synthesis of bioactive fullerene peptides 19 and 20. Synthesis of amino acid–fullerene derivatives 21 and 22. (BtOH is 1H-benzotriazol-1-ol

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• product 145 in 76% yield. The hexacyclic compound 145 was converted to kopsanone (19) in three steps. Miscellaneous In 2012, Wang and co-workers reported a Lewis acid-catalyzed intramolecular [3 + 2] cross-cycloaddition (IMCC) of cyclopropane 1,1-diesters with non-activated alkene to generate bridged [n

• mechanism. (C) The completion of total synthesis of kopsanone (19). (A) Synthesis of phyllocladanol (21) features a Lewis acid-catalyzed formal intramolecular [3 + 2] cross-cycloaddition of cyclopropane 1,1-diesters with alkenes [68]. (B) (5,6-Dihydro-1,4-dithiin-2-yl)methanol 151 used as a versatile allyl

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• cyclic olefins, such as diesters, imides, and lactams with varied functionalization patterns and different structural architectures is described. The synthetic methodologies were based on electrophilic activation through halonium ions of the ring olefin bonds, followed by nucleophilic fluorination with

• (bridgehead alkenes are only stable in large ring systems), elimination was attempted only with (rac)-2a,b, (rac)-5a, (rac)-6b, (rac)-8a,b, and (rac)-11a,b. DBU in THF under reflux was insufficient to promote the elimination of the halofluorinated diesters (rac)-2a,b, (rac)-5a, and (rac)-6b. In contrast, the

• treatment with t-BuOK in THF under reflux was effective. Unexpectedly, all four halofluorinated diesters produced the same condensed ring cyclopropane derivative (rac)-27 (Scheme 15). The stereochemistry of (rac)-27 was determined using NOESY measurements. Regarding the compounds (rac)-2a,b and (rac)-5a

Muyocopronones A and B: azaphilones from the endophytic fungus Muyocopron laterale

• Ken-ichi Nakashima,
• Junko Tomida,
• Tomoe Tsuboi,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 2100–2107, doi:10.3762/bjoc.16.177

• MTPA chloride, enolization and esterification at the C-15 position occurred preferentially over the C-3′ position. Therefore, 2.7 equivalents of the (R)- and (S)-MTPA chlorides were used to prepare the (S)- and (R)-MTPA diesters 1a and 1b, respectively (Scheme 1A). Based on the differences in chemical

• /z): [M + H]+ calcd for C25H33O7, 445.2221; found, 445.2228. Preparation of the MTPA diesters 1a and 1b To a solution of 1 (12.4 mg, 0.028 mmol), DMAP (12.4 mg, 0.10 mmol), and triethylamine (15 μL, 0.11 mmol) in CH2Cl2 (1.2 mL) was added (R)-MTPACl (14 μL, 0.075 mmol). After allowing to stand in the

• experimental ECD spectra (black solid line) of 1 (A) and 2 (B) with the Boltzmann-weighted spectra computed for the (7S,10S,11S)- and (7S,10R,11R)-stereoisomers (green and red dashed lines, respectively) of the simplified models. (A) Synthesis of MTPA diesters 1a and 1b. (B) Δδ Values for the (S)- and (R)-MTPA

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• diesters 20a–c. Partial hydrolysis followed by decarboxylation gave the N-benzyloxycarbonyl ᴅʟ-amino acid esters 22a–c, which upon enzymatic hydrolysis of the ester group using the subtilisin-type Carlsberg enzyme led to ᴅ-amino acid esters 23a–c and the corresponding Cbz-protected p, m-fluoro-, or

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• aliphatic moieties, amide bonds, triple bonds, or ether moieties afforded the desired products in moderate to good yield (156, 158, 162a–e). α,α-Disubstituted aldehydes also afforded the products in good yield and moderate to good selectivity (162f–k). Benzyl diesters and aliphatic diesters were compatible

[1,3]/[1,4]-Sulfur atom migration in β-hydroxyalkylphosphine sulfides

• Katarzyna Włodarczyk,
• Piotr Borowski and
• Marek Stankevič

Beilstein J. Org. Chem. 2020, 16, 88–105, doi:10.3762/bjoc.16.11

• the literature [59]. Another example of such a migration has been reported by Creary and Innocencio for functionalized α-hydroxythiophosphonic acid diesters [60]. What is more interesting, the sulfur atom did not simply replace oxygen at the β-carbon atom: in every case, the mercapto group was placed

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes

• Yo Hiranoi and
• Koji Nakano

Beilstein J. Org. Chem. 2018, 14, 2779–2788, doi:10.3762/bjoc.14.255

• (ROP) of lactones and cyclic diesters [5][6][7][8][9][10]. In contrast to the step-growth polymerization, the ROP does not give any small molecule byproducts and proceeds under mild conditions. In addition, high molecular weight polyesters with narrow polydispersity can be prepared even at a low

• monomer conversion. A variety of lactones and cyclic diesters, such as ε-caprolactone, β-propiolactone, lactic acid (LA), and glycolide have been used for the ROP. However, the employable monomers are rather limited, which restricts the range of polymer properties. In view of the aforementioned, the

Investigation of the electrophilic reactivity of the biologically active marine sesquiterpenoid onchidal and model compounds

• Melissa M. Cadelis and
• Brent R. Copp

Beilstein J. Org. Chem. 2018, 14, 2229–2235, doi:10.3762/bjoc.14.197

• –Wadsworth–Emmons (H.W.E.) reaction of n-hexanal with phosphonoester 19 [15] afforded an E/Z mixture of olefinic diesters, purification of which by silica gel column chromatography afforded a fraction of the desired E diester 20 (60%), a second fraction comprised of a 5:1 E/Z mixture and a third fraction of

• Z diester 21 (10%, Scheme 3). The reduction of diesters 20 (E) and 21 (Z) with LiAlH4 afforded diols 22 and 23 in 63% and 67% yield, respectively. Subsequent oxidation of 22 with DMP afforded dialdehyde 11 in 31% yield. Correspondingly, the reaction of diol 23 with DMP afforded a mixture of

• to onchidal (6) were attempted. H.W.E reaction of 2-cyclohexylacetaldehyde (24) [16] with phosphonoester 19 afforded a fraction of the desired E diester 25 in 15% yield, a fraction of Z diester 26 in 1.5% yield and another fraction of a mixture of the two (5:1) (Scheme 4). The reaction of diesters 25

Oligonucleotide analogues with cationic backbone linkages

• Melissa Meng and
• Christian Ducho

Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

• moderate water solubility and peptide-like folding properties [9] are hurdles for their biological application. As an alternative strategy, the (deoxy)ribose part of the backbone has been retained and only some of the internucleotide phosphate diesters have been selectively replaced by electroneutral

• backbone phosphate diesters, the term 'DNmts' was coined. Just like the guanidinium linkage in DNGs, the S-methylthiourea modification is not stereogenic and stable towards nuclease-mediated cleavage. Furthermore, it retains its positive charge independent of pH conditions. Bruice and co-workers initially

An unusual thionyl chloride-promoted C−C bond formation to obtain 4,4'-bipyrazolones

• Gernot A. Eller,
• Gytė Vilkauskaitė,
• Algirdas Šačkus,
• Vytas Martynaitis,
• Ashenafi Damtew Mamuye,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2018, 14, 1287–1292, doi:10.3762/bjoc.14.110

• of 5-hydroxypyrazole-4-carboxylates in refluxing thionyl chloride. The obtained diesters can be transformed into the corresponding 4,4'-bipyrazoles via alkaline hydrolysis and subsequent decarboxylation. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products

Polysubstituted ferrocenes as tunable redox mediators

• Sven D. Waniek,
• Jan Klett,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86

• . Mono-, 1,1’-diesters and a single 1,1’,3-triester of ferrocene are known [45][46][47][48][49][50][51][52][53]. Elegant routes to 1,1’,3-tris(methoxycarbonyl)ferrocene and 1,1’,3,3’-tetrakis(methoxycarbonyl)ferrocene were developed only very recently [54], complementing the series of methyl esters of