Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones

• Valeria Nori,
• Antonio Arcadi,
• Armando Carlone,
• Fabio Marinelli and
• Marco Chiarini

Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95

• containing electron-donating substituents; electron-poor arylboronic acids proved to be slightly less effective, probably because of their lower nucleophilicity that could have affected the transmetalation step. Moreover, we screened the reaction of a number of aromatic boronic acids 3a–j with a set of N

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• photopolymerization of epoxides [65]. Though [Al(O-t-C4F9)4]− possesses the lowest nucleophilicity in this series, its high molecular weight requires a higher loading to obtain similar OD compared with sensitizers carrying anions with lower molecular weight. There exists still the issue regarding HF formation in the

• . The nitrogens in the cyanine chain still exhibit low nucleophilicity since electron density distributes over the entire methine chain. Thus, protonation of the nitrogen in the cyanine moiety occurs with less efficiency compared to amines [117]. This strategy helped to enable cationic

Microwave-assisted synthesis of 2-substituted 4,5,6,7-tetrahydro-1,3-thiazepines from 4-aminobutanol

• María C. Mollo,
• Natalia B. Kilimciler,
• Juan A. Bisceglia and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2020, 16, 32–38, doi:10.3762/bjoc.16.5

• of the corresponding tetrahydro-1,3-oxazepines. This unexpected reaction path is reasonable considering the relative ease of formation of five-membered rings as compared to the isomeric seven-membered heterocycles together with the relatively poor nucleophilicity of the carboxamide oxygen. An

• energy associated to the formation of a seven-membered heterocycle would favour the competitive ring closure leading to the five-membered ring (Scheme 2, reaction a), which would involve attack of the carboxamide nitrogen to the ω-carbon. On the other hand, the higher nucleophilicity of the sulfur in the

SnCl₄-catalyzed solvent-free acetolysis of 2,7-anhydrosialic acid derivatives

• Kesatebrhan Haile Asressu and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2019, 15, 2990–2999, doi:10.3762/bjoc.15.295

• clearly showed that the NHAc group in position C-5 and the OH-4 group were oriented in a trans-diaxial configuration (Figure 2a). This enhanced the nucleophilicity of the OH-4 group due to the absence of hydrogen bonding between these moieties. After confirming the structure of 4 by single crystal X-ray

Facile regiodivergent synthesis of spiro pyrrole-substituted pseudothiohydantoins and thiohydantoins via reaction of [e]-fused 1H-pyrrole-2,3-diones with thiourea

• Aleksandr I. Kobelev,
• Nikita A. Tretyakov,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev,
• Michael Rubin and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 2864–2871, doi:10.3762/bjoc.15.280

• upon heating at reflux for 2–4 h (Table 5). The facility of thiohydantoins 5 formation could be explained by the electron-donating effect of the butyl substituents, which increased the nucleophilicity of the butyl-substituted nitrogen atoms and promoted its attack on the electrophilic center C-3a of

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• dienophiles (Scheme 5a), whereas pentafulvenes substituted with EDG (e.g., NMe2) at the exocyclic C6 position possess an increased electron density about the fulvene π-system, increasing the stability and hence nucleophilicity of the fulvene [29][73][96][97][98][99][100][101][102][103][104]. This allows the

Installation of -SO₂F groups onto primary amides

• Jing Liu,
• Shi-Meng Wang,
• Njud S. Alharbi and
• Hua-Li Qin

Beilstein J. Org. Chem. 2019, 15, 1907–1912, doi:10.3762/bjoc.15.186

• fluorosulfonyl amides 2 with nucleophilicity may attract significant attention for further applications. As depicted in Scheme 4, a plausible reaction mechanism is proposed for SO2F2-mediated transformation of amides to N-fluorosulfonyl amides. The reaction was initiated by the deprotonation of amide 1 with the

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

• Gabrielle R. Hammersley,
• Meghan F. Nichol,
• Helena C. Steffens,
• Jose M. Delgado,
• Gesine K. Veits and
• Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

• furan ring required to initiate the cascade sequence. This highlights that a balance between nucleophilicity and hydrogen bond capabilities are required to obtain an efficient and selective reaction. Compared to the rearrangement of furylcarbinol 1a, sterically bulky aryl groups attached to the

A novel three-component reaction between isocyanides, alcohols or thiols and elemental sulfur: a mild, catalyst-free approach towards O-thiocarbamates and dithiocarbamates

• András György Németh,
• György Miklós Keserű and
• Péter Ábrányi-Balogh

Beilstein J. Org. Chem. 2019, 15, 1523–1533, doi:10.3762/bjoc.15.155

• reaction conditions. The generally lower yields, harsher reaction conditions and stronger negative effect of electron-donating groups might be explained with the softer nucleophilicity of the thiols compared to the alcohols [100]. All five dithiocarbamate derivatives synthesized are new and were

Novel (2-amino-4-arylimidazolyl)propanoic acids and pyrrolo[1,2-c]imidazoles via the domino reactions of 2-amino-4-arylimidazoles with carbonyl and methylene active compounds

• Victoria V. Lipson,
• Tetiana L. Pavlovska,
• Nataliya V. Svetlichnaya,
• Anna A. Poryvai,
• Nikolay Yu. Gorobets,
• Erik V. Van der Eycken,
• Irina S. Konovalova,
• Svetlana V. Shiskina,
• Alexander V. Borisov,
• Vladimir I. Musatov and
• Alexander V. Mazepa

Beilstein J. Org. Chem. 2019, 15, 1032–1045, doi:10.3762/bjoc.15.101

• cyclic or acyclic CH acids the C5 reaction centre in the 2-amino-4-arylimidazoles possesses higher nucleophilicity than both the exo- and endocyclic amino groups. Regarding the short reaction times of novel Yonemitsu-type reactions that has been achieved without application of any catalyst we assume that

An efficient and concise access to 2-amino-4H-benzothiopyran-4-one derivatives

• Peng Li,
• Yongqi Wu,
• Tingting Zhang,
• Chen Ma,
• Ziyun Lin,
• Gang Li and
• Haihong Huang

Beilstein J. Org. Chem. 2019, 15, 703–709, doi:10.3762/bjoc.15.65

• strong nucleophilicity of piperazine and morpholine, the substrates with electron-donating/withdrawing and halogen groups smoothly delivered the N-substituted 2-aminobenzothiopyranones 4j–o and 4t,u in good to excellent yields. Specifically, the substrates containing a strong electron-withdrawing group

• amines such as arylamines successfully afforded the targeted compounds 4r,s albeit in only about 50% yield. The results indicated that the nucleophilicity of the amine exerts a more pronounced effect on the reactivity (i.e., aliphatic amines vs aromatic amines) under the above optimal conditions

Synthesis and selected transformations of 2-unsubstituted 1-(adamantyloxy)imidazole 3-oxides: straightforward access to non-symmetric 1,3-dialkoxyimidazolium salts

• Grzegorz Mlostoń,
• Małgorzata Celeda,
• Katarzyna Urbaniak,
• Marcin Jasiński,
• Vladyslav Bakhonsky,
• Peter R. Schreiner and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2019, 15, 497–505, doi:10.3762/bjoc.15.43

• occurred more slowly and their completion was established only after 3 d leading to 1-adamantyl-3-alkoxyimidazolium bromides 13d–g. These results indicate that the 1-adamantyloxy substituent enhances the nucleophilicity of the N-oxides and the alkylation requires shorter reaction times. In extension of

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• development does not allow yet to introduce arylamino moieties at C(2) due to the diminished nucleophilicity of anilines. The 7-deazapurine derivatives were characterized with a somewhat larger Stokes shift and bathochromic shift of the lowest energy absorption band in comparison to purine derivatives, but

Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis

• Ferran Planas,
• Michael J. McLeish and
• Fahmi Himo

Beilstein J. Org. Chem. 2019, 15, 145–159, doi:10.3762/bjoc.15.15

• ) were obtained using DFT methods, employing a model of the cofactor along with the hydrogen-bonding carboxylate moiety [23]. Subsequently, a similar approach was used to characterize the nucleophilicity of the N1′ and N4′ centers [24]. In many cases, rather than simply focus on the cofactor

Organometallic vs organic photoredox catalysts for photocuring reactions in the visible region

• Aude-Héloise Bonardi,
• Frédéric Dumur,
• Guillaume Noirbent,
• Jacques Lalevée and
• Didier Gigmes

Beilstein J. Org. Chem. 2018, 14, 3025–3046, doi:10.3762/bjoc.14.282

• , both the polymerization rate and the final conversion were both improved by reducing the nucleophilicity of the anion in cationic polymerization. The photochemical properties of TADF CuC 4 are summarized in Table 6. From Table 6, it is observable that the properties of CuC 4 are compatible with its use

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• strongly depends on the nucleophilicity of the quenching medium. Under the conditions of low nucleophilic work-up with aqueous HCl (Table 3, entry 4), the deprotonation takes place leading to butadiene Z-3a. The predominant formation of the Z-isomer of 3a may reveal that cation Ba undergoes deprotonation

• and recyclization, rather than species C. Quenching of species Ba with water (high nucleophilicity) affords alcohol Z-4a. The formation of compound 4a in exclusively Z-configuration may indicate that cation Ba reacts with H2O in SN2 manner, keeping in mind that carbon C5 in Ba possesses a large

• been studied by NMR and DFT calculations. Depending on electrophilic activator, reaction conditions (temperature, time), and nucleophilicity of media for quenching of solutions of 1,2-oxathiolium ions, these species may undergo various transformations leading to the selective formation of one of the

Synthesis of α-D-GalpN₃-(1-3)-D-GalpN₃: α- and 3-O-selectivity using 3,4-diol acceptors

• Emil Glibstrup and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2018, 14, 2805–2811, doi:10.3762/bjoc.14.258

• nucleophilicity and accessibility of the axial 4-OH versus the equatorial 3-OH [40], we wondered, if this could be used to simplify the synthesis of the α-D-GalpN3-(1-3)-D-GalpN3 unit. When consulting the literature, surprisingly few reports were describing diol glycosylations targeting the galacto-configured

• superior nucleophilicity and accessibility of the 3-OH compared to the axial 4-OH. Initially, a small screening of the glycosylation conditions expected to affect the selectivity was performed. As the donor 15 stems from the acceptor 9, it was decided to use a slight excess (1.2 equiv) of the “less

• % yield. Conclusion In conclusion we have shown, how the difference in nucleophilicity along with steric effects can be utilized to employ an unprecedented regioselective glycosylation on a 3,4-diol, resulting in up to 67% isolated yield. Following general guidelines can be given: With bulky 6-O

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• and has an unpaired electron in the axial dz2 orbital. It acts as a high efficient “radical trap” and reacts with alkyl radicals to yield alkylcob(III)alamin (Figure 1b). Four-coordinated cob(I)alamin has a paired electron in the axial dz2 orbital, resulting in high nucleophilicity with a Pearson

Synthesis of dihydroquinazolines from 2-aminobenzylamine: N³-aryl derivatives with electron-withdrawing groups

• Nadia Gruber,
• Jimena E. Díaz and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2018, 14, 2510–2519, doi:10.3762/bjoc.14.227

• ’-diacylation products were observed due to the low nucleophilicity of the secondary amino group, bearing a deactivating aromatic ring and all desired compounds were obtained with excellent yields (Table 2). Then, the microwave-assisted cyclization reaction leading to 3,4-dihydroquinazolines 1 was initially

Revisiting ring-degenerate rearrangements of 1-substituted-4-imino-1,2,3-triazoles

• James T. Fletcher,
• Matthew D. Hanson,
• Joseph A. Christensen and
• Eric M. Villa

Beilstein J. Org. Chem. 2018, 14, 2098–2105, doi:10.3762/bjoc.14.184

• symmetrical pairings of aldehyde and imine reactants. Under both low and high-temperature conditions, the strongly electron-withdrawing nitro derivative was shown incapable of undergoing condensation. This can be attributed to the poor nucleophilicity of 4-nitroaniline. Condensation efficiency was observed to

• increasingly spontaneous for electron-rich amines partnered with electron-poor formyltriazoles [42]. Another expected outcome was that the condensation steps a, c and d would favor electron-rich amines relative to electron-poor amines, due to their superior nucleophilicity. All high-temperature reactions were

• substituent pairings studied, greatly simplified reaction outcomes were observed for those with nitro substituents. Those trials employing nitroaniline as a reactant showed a lack of imine formation due to its poor nucleophilicity (Table 2, entries 1 and 15). Those trials employing nitro-functionalized

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• to both the electronics of the arene and the nucleophilicity of the amine. Particularly electron-rich arenes such as N-methylindole are not tolerated, as is the case for relatively nucleophilic amines such as imidazoles, anilines or alkylamines. The reported substrates are particularly valuable to

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• desired amide bond (Figure 2, step c). On the other hand, reactions with alcohols proceed at slower rates, for the difference in the nucleophilicity of a primary alcohol and a water molecule is not as prominent as the difference found in amine coupling. Steglich esterification is a widely applied approach

• Figure 6, steps b and c, there is significant concurrence in the nucleophilic attacks of the desired hydroxy group-bearing compound (Figure 6, step b) and water (Figure 6, step c) because of the similar nucleophilicity of these molecules. In other words, water only attacks the activated ester because of

Synthesis of new tricyclic 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepine derivatives by [3⁺ + 2]-cycloaddition/rearrangement reactions

• Lin-bo Luan,
• Zi-jie Song,
• Zhi-ming Li and
• Quan-rui Wang

Beilstein J. Org. Chem. 2018, 14, 1826–1833, doi:10.3762/bjoc.14.155

• of nitriles, the strategy was also probed with aromatic nitriles 9 that were reacted with 8 under the same reaction conditions. The nucleophilicity of the N atom in aromatic nitriles should be lower than that of aliphatic ones owing to the conjugation of the triple bond with the benzene ring. To our

• that various electron-donating and electron-withdrawing groups on the benzene ring were compatible with the reaction conditions furnishing the desired products 10i–r in good yields. This indicated that the nucleophilicity of the nitrogen atom of nitrile 9 is strong enough to override the electronic

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• building block A (Figure 1) under harsh conditions. To obtain dendrimer 6, we expected to exploit the nucleophilicity of the phenoxide groups in the N,N’,N”-tris(4-hydroxyphenyl)melamine B (Figure 1) based on the previous example of P. Gamez and co-workers [41], which involved reaction with 2-chloro[4,6-di