Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N,N-diacyl-β-amino esters

• Youlong Du,
• Haibo Mei,
• Ata Makarem,
• Ramin Javahershenas,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2024, 20, 212–219, doi:10.3762/bjoc.20.21

• efficient way for the synthesis of β-trifluoromethyl β-diacylamino esters. Furthermore, this reaction represents the first example of a Mumm rearrangement of β-trifluoromethyl β-diazo esters. Keywords: β-carbonyl diazo; copper catalyst; fluoroalkyl diazo; Mumm rearrangement; unsymmetrical β-diacylamino

• esters, which enriches the studied content of fluoroalkyl diazo compounds. Results and Discussion Due to the instability of β-carbonyl diazo compounds and the occurrence of possible side reactions [58][59][60][61], screening of reaction conditions to optimize this conversion and inhibit the occurrence of

• ][40][41][58][59], a possible mechanism for this Cu-catalyzed reaction of β-trifluoromethyl β-amino esters was proposed in Scheme 4. Initially, β-trifluoromethyl β-amino ester 1a reacts with tert-butyl nitrite to form trifluoromethylated β-carbonyl diazo intermediate A. Then, the diazo intermediate A

Comparison of glycosyl donors: a supramer approach

• Anna V. Orlova,
• Nelly N. Malysheva,
• Maria V. Panova,
• Nikita M. Podvalnyy,
• Michael G. Medvedev and
• Leonid O. Kononov

Beilstein J. Org. Chem. 2024, 20, 181–192, doi:10.3762/bjoc.20.18

• versus α:β = 13:1 for 2). One could speculate that a more nucleophilic carbonyl oxygen of the chloroacetyl group at O-9 in sialyl donor 2 might participate in a stabilization of the intermediate glycosyl cation from the α-side (as we discussed earlier [52][53]) diminishing the α/β ratio. Conversely, at

Tandem Hock and Friedel–Crafts reactions allowing an expedient synthesis of a cyclolignan-type scaffold

• Viktoria A. Ikonnikova,
• Cristina Cheibas,
• Oscar Gayraud,
• Alexandra E. Bosnidou,
• Nicolas Casaretto,
• Gilles Frison and
• Bastien Nay

Beilstein J. Org. Chem. 2024, 20, 162–169, doi:10.3762/bjoc.20.15

• are excellent substrates for such reactions, affording electrophilic carbonyl derivatives susceptible to react with nucleophiles in the acidic reaction mixture [4][5][6][7][8]. Consequently, the Hock rearrangement is likely to be part of tandem processes involving this carbonyl function [9][10][11

• oxocarbenium 7 and 7’ which exists as a stabilized form including an intramolecular stabilizing interaction between the carbocation and the ester carbonyl group. However, in close agreement with Hess and Baldwin’s values found for the rearrangement of cis-1,3-pentadiene [24], this transition state was high in

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• intermediate. Subsequently, following the production of an oxide ion through the ring-opening reaction of the 2,5-dihydrofuran ring, the oxide ion attacks another TCNEO molecule. This sequence culminates in the elimination of the tetracyanodioxetane moiety (either as dioxetane or carbonyl dicyanide molecules

Visible-light-induced radical cascade cyclization: a catalyst-free synthetic approach to trifluoromethylated heterocycles

• Chuan Yang,
• Wei Shi,
• Jian Tian,
• Lin Guo,
• Yating Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2024, 20, 118–124, doi:10.3762/bjoc.20.12

• 52% (3p) yields, respectively. If the chains did not involve a carbonyl group, the yields were much lower (3q, 25%; 3s, 29%, and 3t, 29%). When a pyrrole ring was used instead of indole, the reaction proceeded but gave the product in low yield (3r). We did not explore the reaction with a primary

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

• expanded by pyrrolo annelation. The optical and redox properties of these compounds, in some cases carbon-rich, were studied by UV–vis absorption spectroscopy and cyclic voltammetry. Synthetically, the work explores IF diones or fluorenone as central building blocks by subjecting the carbonyl groups to a

Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• stabilize the initially formed carbanion as the rate-determining step. A preorganization of the carbonyl bearing Michael acceptors allowed for reasonable fast direct proton transfer from the phenol in aprotic solvents. In contrast, acrylonitrile, not capable of forming a similar preorganization, is hardly

• with several Michael acceptors [34]. In this work we present the formation of stable zwitterions from the reaction of 2,4-di-tert-butyl-6-(diphenylphosphino)phenol (1) and a variety of different Michael acceptors and disclose kinetic investigations on the zwitterion formation with carbonyl and non

• -carbonyl-based Michael acceptors. Results and Discussion Synthesis During our endeavors to identify potent Lewis-base catalysts for the oxa-Michael reaction [13][14], the triarylphosphine 1 was tested in a model reaction (2 equiv allyl alcohol, 1 equiv acrylonitrile, 0.05 equiv 1). However, no conversion

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

• well-known and useful reaction in organic chemistry, affording carbonyl compounds based on an atom-economical approach. Indeed, the addition of water to the triple bond of a terminal alkyne leads to the formation of the corresponding methyl ketone or aldehyde, in the case of Markovnikov or anti

• -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

• ). Unfortunately, any attempt to hydrate disubstituted alkynes containing a carbonyl group adjacent to the triple bond (1m, 1n) with electrogenerated BF3, according to the procedure adopted for the other alkynes, failed, yielding only starting material. We then tried to electrogenerate BF3 in BMIm-BF4, directly in

N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• N–H bond of tetrazoles and 1,2,4-triazole was realized for the first time. This transformation can serve as a powerful tool to carry out N-modification of these heterocycles. Despite all our efforts, it was not possible to obtain N–H insertion products with N-heterocycles containing an α-carbonyl

• group (Figure 2). We observed formation of complex mixtures in the case of δ-valerolactam, glutarimide and oxindole. This observation can be attributed to the competing direction of the attack of the carbenoid onto the carbonyl oxygen atom resulting in unstable intermediates. In the reaction with 5

• have been obtained. Glutarimide-based immunomodulatory drugs (IMiDs) and CRBN ligands. Examples of α-carbonyl NH-heterocycles for which N–H insertion products could not be obtained. Main literature approaches towards α-hetaryl glutarimides 1 (routes A and B) and new “diazo” methodology based on Rh(II

Trifluoromethylated hydrazones and acylhydrazones as potent nitrogen-containing fluorinated building blocks

• Zhang Dongxu

Beilstein J. Org. Chem. 2023, 19, 1741–1754, doi:10.3762/bjoc.19.127

• ], trifluorinated α-methylene-γ-lactams [99][100], and β-trifluoromethyl-β-acylhydrazonyl carbonyl compounds [101] (Scheme 15). Among these fluorinated products, the trifluoromethylated homoallylic acylhydrazines were easily transformed to CF3-substituted pyrazolines and 1,6-dihydropyridazines via a cascade

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• -acylhydrazones were synthesized and fully characterized, both in solution and in the solid state. The compounds differ with respect to the carbonyl precursors, i.e., 3-substituted salicylaldehydes with either a methyl or a nitro group. Single crystals of both compounds were isolated from the respective mother

• derived from the same 3,4,5-trimethoxybenzoic acid hydrazide, but differ with respect to the carbonyl precursors: herein, 3-substituted salicylaldehydes (Scheme 1) are used, which assure for a harder donor-atoms set in order to target trivalent metal ions such as aluminum(III), which has been proposed to

• experimental absorptions were performed not only with the aid of DFT calculations, but also checked by comparing them to the vibrations of the respective carbonyl and hydrazide precursors. Although the phenol-related ν(O–H) bands could not be accurately identified due to overlapping with the water stretching

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• ][50][51]. However, to the best of our knowledge, there are only few examples on the reactions of N–H-type semi-stabilized AMYs B3 or B4 which were either derived from special carbonyl compounds (such as isatin) [52][53][54][55] or the AMYs were reacted with uncommon alkenes as the 1,3-dipolarophiles

Sulfur-containing spiroketals from Breynia disticha and evaluations of their anti-inflammatory effect

• Ken-ichi Nakashima,
• Naohito Abe,
• Masayoshi Oyama,
• Hiroko Murata and
• Makoto Inoue

Beilstein J. Org. Chem. 2023, 19, 1604–1614, doi:10.3762/bjoc.19.117

• formula of C45H64O28SNa (calcd 1107.3197). The IR spectrum showed absorption peaks corresponding to hydroxy groups (νmax = 3414 cm−1) and carbonyl groups (νmax = 1782 and 1695 cm−1). The 1H NMR signals (Table 1) were characteristic of a breynogenin moiety, namely, a methyl group [δH 0.92 (d, J = 6.9 Hz

• observed resonances including a carbonyl group [δC 212.3 (C-8)], a spiroketal center [δC 100.6 (C-9)], and a p-hydroxybenzoate [δC 167.6 (C-19), 122.7 (C-20), 133.2 (C-21, 25), 116.7 (C-22, 24), 163.4 (C-23)]. The presence of a breynogenin-α-S-oxide moiety was further evidenced by HSQC, HMBC, and double

• correlations of H-5/C-3, H-16/C-3, and H-17/C-4. The linkage between C-6 and C-7 was supported by the HMBC correlations of H-5/C-6 and H-16/C-5. Furthermore, the presence of a carbonyl group was indicated by the HMBC correlations of both H-5 and H-17 with a carbonyl carbon (δC 177.1). Thus, the structure of

Secondary metabolites of Diaporthe cameroonensis, isolated from the Cameroonian medicinal plant Trema guineensis

• Bel Youssouf G. Mountessou,
• Élodie Gisèle M. Anoumedem,
• Blondelle M. Kemkuignou,
• Yasmina Marin-Felix,
• Frank Surup,
• Marc Stadler and
• Simeon F. Kouam

Beilstein J. Org. Chem. 2023, 19, 1555–1561, doi:10.3762/bjoc.19.112

• overlapping at δH 2.28 due to two acetyl groups, which showed strong HMBC cross peaks with the carbonyl carbon signals at δH 169.0. The structure of 2 was fully assigned by using the 13C NMR spectrum which displayed sixteen carbon signals sorted into three methyl signals of which two overlapping ones at δC

Morpholine-mediated defluorinative cycloaddition of gem-difluoroalkenes and organic azides

• Tzu-Yu Huang,
• Mario Djugovski,
• Sweta Adhikari,
• Destinee L. Manning and
• Sudeshna Roy

Beilstein J. Org. Chem. 2023, 19, 1545–1554, doi:10.3762/bjoc.19.111

• ; gem-difluoroalkenes; organic azides; Introduction gem-Difluoroalkenes and their synthetic preparations soared in the last decade, driven by the high demand for carbonyl mimics in medicinal chemistry and drug discovery [1]. Although a wide array of functionalization strategies for gem-difluoroalkenes

• are typically accessed in two ways: (1) direct synthesis using metal or metal-free catalysis and (2) post-functionalization of disubstituted-1,2,3-triazoles [17][18]. The direct synthesis of fully substituted triazoles entails either metal-free carbonyl-based [19][20][21] or metal-mediated and strain

• regioselective reaction that does not rely on carbonyl- or alkyne-based methods or late-stage modifications to access 1,4,5-trisubstituted-1,2,3-triazoles. However, carbonyl chemistry was utilized to synthesize the gem-difluoroalkene starting material [30]. In fact, our findings offer a straightforward direct

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• ][22]. On the other hand, Pro/Gly DES may also activate carbonyl groups as suggested by Mohire et al. [23] and Theresa et al. [24]. In any event, the DES structure in Pro/Gly seems to play an important role in promoting the reaction. 5-Methylfurfural was selected as another model substrate and similar

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• carbonyl compounds 168 can be achieved with N-thiophthalimides 14 and diaryl disulfides 47, respectively (Scheme 73) [104]. They remarked that the presence of B2pin2 was essential in the coupling reaction of disulfides with α,β-unsaturated carbonyl compounds 168. The sulfenylation involved a 1,4-addition

• HCl-promoted 1,2-thiofunctionalization of aromatic alkenes. Coupling reaction of diazo compounds with N-sulfenylsuccinimides. Multicomponent reactions of disulfides with isocyanides and other nucleophiles. α-Sulfenylation and β-sulfenylation of α,β-unsaturated carbonyl compounds.

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• -enones) undergo intramolecular transformation into 3-trichloromethylindan-1-ones (CCl3-indanones) in Brønsted superacid CF3SO3H (triflic acid, TfOH) at 80 °C within 2–10 h in yields up to 92%. Protonation of the carbonyl oxygen of the starting CCl3-enones by TfOH affords the key reactive intermediates

• form of the starting compound [Cl3CCH=CHC(=OH+)Me]. The presence of two strong electron-withdrawing substituents, the trichloromethyl group (CCl3) and a protonated carbonyl (C(OH+)Me), at the carbon–carbon double bond makes this O-protonated species electrophilic enough to react with arenes (Scheme 1a

• atoms H2 and H3 in cations Aa,c,d and their neutral precursors 1a,c,d were 0.59–0.86 and 0.28–0.31 ppm (Table 2). These downfield shifts of the signals point to an inductively induced positive charge on these hydrogens due to the protonation of the oxygens of the carbonyl and hydroxy groups. According

α-(Aminomethyl)acrylates as acceptors in radical–polar crossover 1,4-additions of dialkylzincs: insights into enolate formation and trapping

• Angel Palillero-Cisneros,
• Paola G. Gordillo-Guerra,
• Fernando García-Alvarez,
• Olivier Jackowski,
• Franck Ferreira,
• Fabrice Chemla,
• Joel L. Terán and
• Alejandro Perez-Luna

Beilstein J. Org. Chem. 2023, 19, 1443–1451, doi:10.3762/bjoc.19.103

• atom to zinc enables this SH2 process which represents a rare example of alkylzinc-group transfer to a tertiary α-carbonyl radical. The zinc enolate thus formed readily undergoes β-fragmentation unless it is trapped by electrophiles in situ. Enolates of substrates having free N–H bonds undergo

• protodemetalation to provide ultimately the 1,4-addition adduct. In the presence of carbonyl acceptors, aldol condensation occurs providing overall a tandem 1,4-addition–aldol process. When a tert-butanesulfinyl moiety is present on the nitrogen atom, these electrophilic substitution reactions occur with good

• carbonyl compounds to provide the corresponding zinc enolates (Scheme 1) [1][2]. While simple, this reaction offers attractive features: 1) it proceeds under mild conditions in the absence of any transition-metal catalyst; 2) the 1,4-addition step can be combined with condensation reactions of the zinc

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

• ]. Later in 2003, Buchwald, Sadighi and Jurkauskas [47] succeeded in the application of [(IPr)CuCl] as NHC–Cu(I) complex to catalyze the conjugate reduction of α,β-unsaturated carbonyl compounds. In the decade following these initial reports, the field has blossomed and NHC–Cu(I) complexes have been

• been found to be highly efficient catalysts in this transformation. Nolan and co-workers reported the catalytic activity of [Cu(IPr)Cl] in the hydrosilylation of carbonyl compounds to form silyl ethers in high yield [48][49]. A series of bis-NHC–copper complexes was synthesized and the compounds were

• . The hydrosilylation of aryl, alkyl, and cyclic ketones could be accomplished with excellent yields (Scheme 35) [48]. In 2011, Gawley and co-worker reported an excellent reactivity and enantioselectivity of a C2-symmetric NHC–Cu(I) complex for the catalytic hydrosilylation of a variety of carbonyl

One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• cannot rigorously exclude their formation. Compared to bis(1,2,3-triazoles) 14 and 17, compounds 20 and 21 are one step closer to the desired divalent aminopyran-substituted carbohydrate mimetics, since they already contain a free hydroxy group instead of the carbonyl group. However, their reductive

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

• involved in the activation of DDQ by coordinating the carbonyl oxygen atom which leads to an increase in the oxidation activity of DDQ. Subsequently, Li et al. improved the above method, using a mixture of indium and copper salts as a catalyst, NHPI (N-hydroxyphthalimide) as a co-catalyst to achieve the

• form the coupling product. However, this method is only applicable to cyclic ethers. In the same year, Correa et al. established a double C(sp3)–H functionalization reaction of α-amino carbonyl compounds and 2-alkyl-1,3-dioxolanes in the presence of Cu(I) (Scheme 6b) [55]. This method allows the

• synthesis of compounds with quaternary centers and natural products with high structural complexity. In 2014, Li et al. reported a CuCl2-catalyzed cross-dehydrogenation coupling reaction of C(sp3)–H bonds adjacent to an ether oxygen and the C(sp3)–H bonds at the α-position of a carbonyl functionality in the

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• effect. The single crystal structure of compound 3a was determined by X-ray crystallographic diffraction (Figure 1). From Figure 1 it can be seen that the two scaffolds of oxindole at neighboring positions are in trans-configuration. The ethoxycarbonyl group is also in trans-position to the carbonyl

• showed that the carbonyl group of the dimedone does not take part in the further cyclization reaction, while the carbonyl group of the benzoyl group participated in the annulation reaction to give the pyrrolidyl ring. This result clearly indicated that the adducts of 3-phenacylideneoxindoles showed

• dimedone moiety is also in trans-position to the carbonyl group in the neighboring oxindole scaffold. To demonstrate the synthetic value of this three-component reaction, 3-phenacylideneoxindole adducts of 1,3-cyclohexanedione were also employed in the reaction. In the presence of piperidine, the three

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• sacrificial donors [40]. More recently, other groups have published the electrochemical hydrogenation of carbonyl compounds using more earth-abundant electrocatalysts. For instance, Siewert and co-worker used a manganese complex as an electrocatalyst for the chemoselective carbonyl hydrogenation [41

• ]. Behrouzi et al. reported the electrochemical hydrogenation of carbonyl and amido compounds using nickel electrodes and water as the proton and electron source [42]. Furthermore, the carbonyl and amido compounds used in these electrochemical hydrogenation studies are more structurally similar to organic

• systems and photosensitizers to enable direct electron transfer between them. In contrast to the system of Domen where the photoexcitation only occurs at the Al-SrTiO3 particle [53], the system developed by Ishitani included a second ruthenium chromophore linked the TaON particle to a ruthenium carbonyl

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• found were intermolecular interactions between the lone pairs of either the carbonyl or sulfonyl with the other I–C bond σ* orbital, at energies of 0.70 and 0.29 kcal/mol, respectively. These interactions were presumed to have contributed to the increased stability of such ylides. X-ray crystal