Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• deprotonation the latter with sodium hydride base. The compound shows poor solubility in most common organic solvents with moderate solubility in dichloromethane, 1,2-dichlorobenzene and dimethyl sulfoxide (DMSO). Compound 4BGIPN was characterized by high-resolution mass spectrometry (HRMS), elemental analysis

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

• carbocation D. Finally, the nucleophile attacks the carbocation D, to obtain the final coupled product. The deprotonation of the nucleophile occurs before or after the attack on the carbocation intermediate, depending on the acidity of the nucleophile. In 2008, Li et al. reported that Fe2(CO)9 as a catalyst

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

• sulfides, or a separate deprotonation event can also result in similar behavior. Gimeno et al. highlighted this when they designed novel benzimidazole (BIH) donors for the photoreduction with [Cu(dipp)2]2+ photocatalysts [29][30]. They contrasted their work to a previous study by Cunningham and McMillin

• ]. This can be explained by the low oxidation potentials (0.31 to −0.47 V vs Fc/Fc+) amongst other factors. Bases are often added to enhance the quenching rate by deprotonation of benzimidazoles which means they are commonly used with TEA or TEOA [29][30]. Benzimidazoles are also one of the redox

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• the formate via SET to 4-DPAIPN and successive deprotonation by a second formate anion (Figure 11B). Due to its reducing nature, CO2•− (E0 = −2.2 V vs SCE) may promote the photoreductant activity either by reducing another equivalent of photocatalyst or the direct reduction of sufficiently electron

• the corresponding carbocation 4+ while simultaneously generating S32−. Subsequent deprotonation of 4+ yields the C–H arylated product 4 while SET between S4•− and S32− regenerates the catalytically active polysulfide species S42− and S3•− and closes both catalytic cycles. Showing high versatility, the

• ). Nucleophilic addition of the amine to the acyl radical and amine-assisted intermolecular proton transfer [84] generates the α-hydroxy radical 24 from which formation of the amide 25 proceeds either via i) oxidation by [Ir2]+ and deprotonation or ii) radical chain propagation [85]. Electron-deficient, electron

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• carbonyl carbon to form the 5-membered ring E bearing the iminium ion. Finally, N-substituted amines 67 were obtained after deprotonation/protonation, dehydration, and aromatization steps as shown in Scheme 32b. In another report, Ozaki et al. [87] used the Clauson–Kaas approach to synthesize sulfonic

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• mechanism involves the coordination of pyridine to the metal center of the cationic catalyst and B(C6F5)3 promotes the ortho-C–H activation (deprotonation) of pyridine to afford pyridyl species 6. Next, the 2,1-migratory insertion of alkene 2 into the metal–pyridyl bond in 6 gives the intermediate 7, which

• on subsequent deprotonation gives the branched alkylated product 4. Whereas, in case of styrene 3 a 1,2-insertion takes place possibly due to the formation of the stable benzallylic species 8, which on deprotonation gives the linear alkylated product 5. The C–H activation/C–C cross-coupling reaction

• 205 were accessed in moderate to excellent yields and also naphthyridine derivatives (205k and 205l) were synthesized. In the proposed mechanism, the initial deprotonation of HNBn2 by Ln[N(TMS)2]3 provided the lanthanide amide. Activation of the vinyl-substituted pyridin-3-amine 204 by the lanthanide

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• reactions involve the imidothioate IV formed via deprotonation from nitrogen (pKaN in Scheme 2). The imidothioate IV can undergo cyclization to give an energetically favorable five-membered thiazoline ring VII which then either eliminates a leaving group Y− (when Y: alkoxy, amino) or a water molecule (when

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• -dihydrodibenzo[b,f]heteropines via intramolecular Wurtz reaction. Phenol deprotonation and intramolecular etherification in the synthesis of bauhinoxepine J. Palladium-catalysed N-arylation of dibenzo[b,f]azepine. Cu- and Ni-catalysed N-arylation. N-Alkylation of dibenzo[b,f]azepine (1a) and dihydrodibenzo[b,f

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• array of organic synthetic transformations. Enolates are usually formed by deprotonation of the corresponding organic compound. However, other synthetic approaches for their generation exist, such as cleavage of enol ethers and esters, halogen–metal exchange, transmetalations, and conjugate additions to

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

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

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• (established via the α-protonation/deprotonation in the intermediate α-carbanion in the amino acid moiety) and concomitant epimerization of the final product [41]. The results of the thiolation of complex (ΔAlaNi)L7 are given in Table 1. The corresponding ʟ-cysteine derivatives (RCysNi)L7 were isolated in high

• complexes derived from various chiral ligands. The oxidation potential can be determined from the voltammetry curve measured for the quantitatively deprotonated complex. The electrochemical deprotonation using an electro-generated base is the most convenient approach [37][44]. Comparison with the Eox values

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

• Austin Pounder,
• Eric Neufeld,
• Peter Myler and
• William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

• photoexcitation of the photosensitizer 43 to form 44 which can oxidize aniline 36a to give radical cation 46 (Scheme 7). Deprotonation by DBU produces the radical 40. The radical anion photosensitizer 45 can reduce Ni(I) to Ni(0), closing the first catalytic cycle. The Ni(0) complex can undergo oxidative addition

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• events in which all bonds involved in the cycloaddition are formed and broken and (ii) a second one consisting of the deprotonation of the nitrogen yielding a neutral compound and liberating the catalyst. The comparative quantitative analysis of the noncovalent interactions (NCI) [35][36] of fused

Transition-metal-catalyzed C–H bond activation as a sustainable strategy for the synthesis of fluorinated molecules: an overview

• Louis Monsigny,
• Floriane Doche and
• Tatiana Besset

Beilstein J. Org. Chem. 2023, 19, 448–473, doi:10.3762/bjoc.19.35

• C(sp2)–H bond activation involving a concerted metalation–deprotonation pathway affords the metallacycle K. After an oxidative addition in the N-SCF3 bond of the Munavalli reagent V, the palladium(IV) species L is obtained. Finally, the reductive elimination affords the product and regenerates the

• isolated in 70% yield. Mechanistic studies indicated that the C–H bond activation event was the rate-limiting step and the authors suggested a similar mechanism to the one depicted in Scheme 20: formation of a palladacycle thanks to a concerted metalation deprotonation (CMD) process followed by oxidation

Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• , entry 10). Instead of small amounts of liquid, here, deprotonation leads to the formation of dihydrogen. Hence, another gastight mill was utilized for this approach. Unfortunately, a successful synthesis of 5 directly from 3 was not possible under these conditions: NMR analysis of the resulting mixture

Asymmetric synthesis of a stereopentade fragment toward latrunculins

• Benjamin Joyeux,
• Antoine Gamet,
• Nicolas Casaretto and
• Bastien Nay

Beilstein J. Org. Chem. 2023, 19, 428–433, doi:10.3762/bjoc.19.32

• PMB group in 72% yield (18), after deprotonation with NaH and reaction with PMBBr. The ester moiety of 18 was then chemoselectively reduced into alcohol 19 in 90% yield, in presence of LiBH4 to avoid the reduction of the thiazolidinone part. Finally, the aldehyde (8) was generated in 78% yield by

Group 13 exchange and transborylation in catalysis

• Dominic R. Willcox and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

• frustrated Lewis pair (FLP)-mediated C‒H functionalisation (Scheme 4a). Using computational analysis, the mechanism of the reaction was proposed to occur by borane dimer [9]2 dissociation, followed by a concerted deprotonation of the heterocycle 10 to give a zwitterionic intermediate 11. The zwitterion then

• fastest during catalyst activation, rather than during catalysis, leading to an in-depth investigation of catalyst activation using variable time normalisation analysis (VTNA) and kinetic isotope effects. A catalytic cycle was proposed in which (Me2N)C6H4AlH2 83 underwent deprotonation of the alkyne 1 to

• benzyl fluorides and the proposed mechanism. Borane-catalysed S‒H borylation of thiols and the proposed mechanism. Borane-catalysed hydroalumination of alkenes and allenes. a) Aluminium-catalysed hydroboration of alkynes and example catalysts. b) Deprotonation mechanistic proposal. c) Hydroalumination

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

• (177), albolic acid (178), and ceroplastol II (179) (Scheme 37). For the synthesis of hypoestin A (177), the side chain was introduced by selective deprotonation of 184, addition of acetaldehyde, dehydration and conjugated addition of Me2CuLi. These three last steps provided the desired product 177 in

• 50% overall yield. For the synthesis of albolic acid (178) and ceroplastol II (179), the side chain was introduced by deprotonation and addition of the corresponding aldehyde. After dehydration of the subsequent alcohol and conjugated addition of Me2CuLi, the regioselective reductive opening of

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• is terminated by deprotonation to yield a terpene hydrocarbon or by nucleophilic attack of water to generate a terpene alcohol. For the precursor of sesquiterpenes FPP six initial cyclisation modes are possible (Scheme 1). After ionisation to A either a 1,10-cyclisation to the (E,E)-germacradienyl

• combined computational and experimental approach that in this enzyme the main chain carbonyl oxygen of Gly182 near the helix G kink and an active site water are involved in the deprotonation–reprotonation sequence in the biosynthesis of 10 (Scheme 8B) [69]. γ-Selinene (10) has been synthesised from ketone

• that 11 can bind to the main protease Mpro of the SARS-CoV-2 virus that is involved in viral reproduction, but experimental tests supporting this finding are lacking [89]. Selina-5,7(11)-diene (20) can arise from I1 through 1,2-hydride shift to I1a and deprotonation (Scheme 7). This compound was first

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

• Benedikt Kolb,
• Daniela Silva dos Santos,
• Sanja Krause,
• Anna Zens and
• Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

• -butyllithium and 5 equiv of alkyl iodide led to isolation of the alkyl-substituted compounds 25g–j with up to 54% yield. The reaction of 29a and 29f with TBAF·H2O gave bromoenynes 25m in 13% and 25n in 52% yield. Deprotonation of 25a and 25f with n-butyllithium and reaction with ethyl chloroformate yielded 25k

Revisiting the bromination of 3β-hydroxycholest-5-ene with CBr₄/PPh₃ and the subsequent azidolysis of the resulting bromide, disparity in stereochemical behavior

• Christian Schumacher,
• Jas S. Ward,
• Kari Rissanen,
• Carsten Bolm and
• Mohamed Ramadan El Sayed Aly

Beilstein J. Org. Chem. 2023, 19, 91–99, doi:10.3762/bjoc.19.9

• C3 hydroxy of 1 is activated. Deprotonation of 10 at C2 with bromide as base provides diene 9 as the minor product. Bromide 4 is formed via cyclopropyl cation 11, which is generated from 10 by loss of triphenylphosphine oxide being supported by involvement of the Δ5 π-bond electrons from the α-face

Catalytic aza-Nazarov cyclization reactions to access α-methylene-γ-lactam heterocycles

• Bilge Banu Yagci,
• Selin Ezgi Donmez,
• Onur Şahin and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2023, 19, 66–77, doi:10.3762/bjoc.19.6

• starting from the commercially available triethyl phosphonoacetate (14, Scheme 2a). The deprotonation of 14 with NaH followed by alkylation using (iodomethyl)trimethylsilane afforded phosphonate 15 in 60% yield (7.0 g). Its subsequent Horner–Wadsworth–Emmons reaction with isovaleraldehyde resulted in the

Synthetic study toward tridachiapyrone B

• Morgan Cormier,
• Florian Hernvann and
• Michaël De Paolis

Beilstein J. Org. Chem. 2022, 18, 1741–1748, doi:10.3762/bjoc.18.183

• deprotonation of 2-(α’-methoxy-γ-pyrone)-1,3-dithiane. The resulting vinylogous enolate intermediate was trapped with the electrophile 3, amounting to the one-pot preparation of compound 4, having a masked carbonyl function connecting both key fragments [27][28]. Isolated and characterized by Schmitz [17], the

Total synthesis of grayanane natural products

• Nicolas Fay,
• Rémi Blieck,
• Cyrille Kouklovsky and
• Aurélien de la Torre

Beilstein J. Org. Chem. 2022, 18, 1707–1719, doi:10.3762/bjoc.18.181

• substituted cyclohexanone 9, corresponding to the future C ring [24]. After deprotonation, the C3 position was stereoselectively alkylated using propargyl bromide, and the benzyl protecting group was cleaved with FeCl3, leading to spontaneous lactone closure. A Luche reduction stereoselectively converted

• secondary alcohol was oxidized by DMP, the tertiary alcohol was triflated, 4-phenylpyridine was added and the mixture was heated at 80 °C for 14 h. The intermediate carbocation was trapped by the terminal olefin, generating a dienone 51 after deprotonation at the relatively acidic position C2. A singlet

• oxygen ene reaction involving the electron-rich olefin allowed the formation of an aldehyde, which was directly cleaved by an iridium-catalyzed deformylation, affording 52 in one-pot [36]. Deprotonation with KHMDS allowed the formation of an electron-rich diene which could again react with singlet oxygen

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

• coupling, or deprotonation followed by the functionalization of α- and β-positions of the starting aldehyde. NHC-catalyzed photochemical processes [64] and oxidative cyclizations with heterocycle formation [65] were reviewed previously. Acidic molecules or hydrogen-bond donors are used as organocatalysts

• via a SET mechanism. The first electron transfer occurs from the aromatic system to the organocatalyst cation radical. After the deprotonation of the benzylic position a benzylic radical is formed. Then, a benzylic cation is produced by a second oxidative electron transfer followed by nucleophile

• high hydrogen binding energy and low deprotonation free energy. N-Ammonium ylides were used for the electrochemical oxidation of unactivated C–H bonds (Scheme 37). Ylides showed good selectivity and an unusual reactivity pattern in comparison with known mediators for CH-oxidation. For example, a

Synthesis of (−)-halichonic acid and (−)-halichonic acid B

• Keith P. Reber and
• Emma L. Niner

Beilstein J. Org. Chem. 2022, 18, 1629–1635, doi:10.3762/bjoc.18.174

• envisioned for this carbocation (e.g., a nucleophilic attack of formic acid to give a formate ester), only alkene formation was observed in this system. Interestingly, the deprotonation step is completely regioselective, giving the more highly substituted endocyclic trisubstituted alkene found in 8 as

• opposed to the isomeric exocyclic 1,1-disubstituted alkene [7][8]. Alternative mechanistic pathways involving (1) deprotonation to form a bridgehead alkene, or (2) intramolecular nucleophilic attack of the ethyl ester to form a lactone are not possible in this system due to the rigid geometric constraints