Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

• observed for diarylamines. The biguanides were synthesized by subsequent reaction of the intermediates with another primary amine hydrochloride with generally fair yields. In 2009, Maeda et al. reported the synthesis of a series of dialkylbiguanides as intermediates for antiseptic compounds (Scheme 25) [58

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• yield from 69% to 84% over the conventional protocol as observed during the study. The explored mechanism in Scheme 16 indicates an in situ anti-azomethine ylide (A) generation (between isatin and primary amine) favored due to steric hindrance in syn-ylide. The crucial step determines the route via

• electron-rich pyrazolylamine led to the formation of intermediate A. Simultaneously, intermediate B (condensation of arylgyoxal and primary amine 32b undergoes C=N addition with intermediate A. Intramolecular cyclization of C yields a macrocyclic intermediate D which is followed by p-TsOH-promoted ring

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

• efficient synthesis of triazoles with different substitution pattern. One important methodology developed by the Sakai group involved the reaction of α,α-dichloroketone, tosyl hydrazide and primary amine [20]. However, in this case, the unstable α,α-dichlorohydrazone intermediate had to be isolated which

Asymmetric Mannich reactions of (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines with yne nucleophiles

• Ziyi Li,
• Li Wang,
• Yunqi Huang,
• Haibo Mei,
• Hiroyuki Konno,
• Hiroki Moriwaki,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2020, 16, 2671–2678, doi:10.3762/bjoc.16.217

• conditions and the target primary amine 4 was obtained with 57% yield. Conclusion In conclusion, we have explored arylethynes as new nucleophiles for the Mannich reactions of (R)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimine. Quite unexpectedly, the diastereoselectivity of the reactions were noticeably

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction

• Tony Jin,
• Malickah Hicks,
• Davis Kurdyla,
• Sabahudin Hrapovic,
• Edmond Lam and
• Audrey Moores

Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201

• ChNCs and ChsNCs confirmed the structural and chemical functional properties of these nanomaterials. We turned to Fourier transform infrared (FTIR) spectroscopy to access the degree of deacetylation (DDA) of the prepared materials (Supporting Information File 1, Figure S2). The ratio of primary amine

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• then reduce 3-nitrobenzoic acid to the corresponding aniline 25 to turn over the cobalt cycle. Simultaneously, 23 condenses with the chiral primary amine catalyst 26 to give enamine intermediate 27, which can be intercepted by 24 to generate imine intermediate 28, which is finally hydrolysed to turn

Controlling the stereochemistry in 2-oxo-aldehyde-derived Ugi adducts through the cinchona alkaloid-promoted electrophilic fluorination

• Yuqing Wang,
• Gaigai Wang,
• Anatoly A. Peshkov,
• Ruwei Yao,
• Muhammad Hasan,
• Manzoor Zaman,
• Chao Liu,
• Stepan Kashtanov,
• Olga P. Pereshivko and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2020, 16, 1963–1973, doi:10.3762/bjoc.16.163

• -component reaction (U-4CR) a carboxylic acid 1, an aldehyde 2, and an isocyanide 3 are complemented by a primary amine 5 that altogether undergo a condensation into a peptide-like adduct 6. These reactions are typically conducted in polar protic solvents such as methanol or water. Several examples of

• been elaborated allowing the engagement of different classes of substrates (Table 2). In addition, the group of Tan adapted their findings to the chiral phosphoric acid-catalyzed three-component Ugi reaction of an aldehyde 2, an isocyanide 3, and a primary amine 5 [58]. As a part of our ongoing

Tuneable access to indole, indolone, and cinnoline derivatives from a common 1,4-diketone Michael acceptor

• Dalel El-Marrouki,
• Sabrina Touchet,
• Abderrahmen Abdelli,
• Hédi M’Rabet,
• Mohamed Lotfi Efrit and
• Philippe C. Gros

Beilstein J. Org. Chem. 2020, 16, 1722–1731, doi:10.3762/bjoc.16.144

• . The reaction mechanism shown in Scheme 3 involves the formation of an imine upon the reaction of the primary amine with the most reactive carbonyl moiety (nonconjugated and exocyclic carbonyl function). Then, depending on the reaction conditions, the imine can react following a 1,2- or 1,4-addition

• directing the reaction exclusively towards indole formation by reacting the diketone with appropriate substrates, combining a primary amine with a tertiary amine or a pyridine separated by several spacer arms (Scheme 6). Under these conditions, the functional indoles 6h–l were obtained exclusively in 45–55

• % yield (Scheme 7). Here again, the amount of indolone was found to be almost constant, whatever the amine involved was, suggesting that the reaction is not dependent on the nature of the amine. It is worth to notice that, for a substrate combining a primary amine with a pyridine separated by a spacer arm

Microwave-assisted efficient one-pot synthesis of N²-(tetrazol-5-yl)-6-aryl/heteroaryl-5,6-dihydro-1,3,5-triazine-2,4-diamines

• Moustafa Sherief Moustafa,
• Ramadan Ahmed Mekheimer,
• Saleh Mohammed Al-Mousawi,
• Mohamed Abd-Elmonem,
• Hesham El-Zorba,
• Afaf Mohamed Abdel Hameed,
• Tahany Mahmoud Mohamed and
• Kamal Usef Sadek

Beilstein J. Org. Chem. 2020, 16, 1706–1712, doi:10.3762/bjoc.16.142

• attack of the primary amine in 7 to the same imine carbon produces the corresponding N2-(tetrazole-5-yl)-6-aryl-1,3,5-triazine-2,4-diamines 4 (route b). Alternatively, intermediate 8 could be obtained by a condensation of 5-aminotetrazole (3) with aromatic aldehydes 2 followed by the addition of

Synthesis of 3-alkenylindoles through regioselective C–H alkenylation of indoles by a ruthenium nanocatalyst

• Abhijit Paul,
• Debnath Chatterjee,
• Srirupa Banerjee and
• Somnath Yadav

Beilstein J. Org. Chem. 2020, 16, 140–148, doi:10.3762/bjoc.16.16

• different functional groups (Table 2). It was found that the reactions tolerated carboxylic acid, ketone, halogen (Cl, Br, I, and F), aldehyde, amide, primary amine, secondary amine, and phenolic functional groups to a reasonably acceptable extent. Recovery and recyclability of the Ru nanocatalyst The

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• , Luo’s group disclosed another potential application of integrating electrochemical oxidation with chiral amine catalysis [77]. Using chiral primary amine 130 as a catalyst, the authors reported an electricity-driven cross-dehydrogenative coupling of ketones 129 with tertiary amines 128. The

Synthesis and properties of sulfur-functionalized triarylmethylium, acridinium and triangulenium dyes

• Marco Santella,
• Eduardo Della Pia,
• Jakob Kryger Sørensen and
• Bo W. Laursen

Beilstein J. Org. Chem. 2019, 15, 2133–2141, doi:10.3762/bjoc.15.210

• groups by one primary amine gives acridinium-type ring systems (Figure 2, step 2) and is a key reaction for the formation of the unsubstituted triangulenium dyes shown in Figure 1b [19][20]. Finally, formation of oxygen bridges in the triangulenium system (Figure 2, step 3) involves demethylation

• types of SNAr reactions typical in triangulenium synthesis, exemplified with the synthesis of A3-ADOTA+: step 1, replacement of p-methoxy groups with dialkylamines. Step 2, replacement of o-methoxy groups with a primary amine followed by intramolecular SNAr reaction. Step 3, intramolecular SNAr

• ] lacking para-substituents and for the para-amino-substituted analogue [17] (step 2 in Figure 1). It was found that the reactivity in SNAr reactions of 1 with primary amines was high and the acridinium compounds 4a,b were obtained in few minutes after the addition of 2 equiv of the corresponding primary

Synthesis of pyrrolo[1,2-a]quinolines by formal 1,3-dipolar cycloaddition reactions of quinolinium salts

• Anthony Choi,
• Rebecca M. Morley and
• Iain Coldham

Beilstein J. Org. Chem. 2019, 15, 1480–1484, doi:10.3762/bjoc.15.149

• ylide, or by condensation of a primary amine with an aldehyde to give an imine followed by prototropy or deprotonation to give N-metalated azomethine ylides (see, for example, [5][6][7][8][9][10][11][12][13][14][15][16][17][18]). An alternative method is to prepare a salt of a heterocycle, typically by

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• water-soluble crown macrocycle 3 was synthesized according to reported protocols, by using potassium cations as template [86][87]. The primary amine group in 3 offers diverse reaction pathways to design crown ethers appended LMW gelators, dendrimers and polymers [88][89][90][91][92]. In order to

A three-component, Zn(OTf)₂-mediated entry into trisubstituted 2-aminoimidazoles

• Alexei Lukin,
• Anna Bakholdina,
• Anna Kryukova,
• Alexander Sapegin and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2019, 15, 1061–1064, doi:10.3762/bjoc.15.103

• .15.103 Abstract A three-component reaction involving in situ generation of propargylureas and subsequent Zn(OTf)2-mediated cyclocondensation with a primary amine yielded trisubstituted 2-aminoimidazoles. These findings are in contrast to the previously reported base-promoted unimolecular cyclization of

• possibility to incorporate of an external primary amine into the cyclization process, which would lead to trisubstituted 2-aminoimidazoles 5 has not been explored (Figure 1). 2-Aminoimidazoles have a remarkably broad utility in medicinal chemistry [7]. Moreover, ureas 4 can, in principle, be generated in situ

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• primary amine 8 was coupled with ALA in the presence of COMU–DIPEA to furnish the second title compound 7 in 68% yield. Indeed, a bathochromic shift of the spectral data was observed (absorption at 514 nm and emission at 566 nm). Spectroscopy. Being typical push–pull aromatic systems, all DAT derivatives

Heck- and Suzuki-coupling approaches to novel hydroquinone inhibitors of calcium ATPase

• Robert J. Kempton,
• Taylor A. Kidd-Kautz,
• Soizic Laurenceau and
• Stefan Paula

Beilstein J. Org. Chem. 2019, 15, 971–975, doi:10.3762/bjoc.15.94

• at C-8 of TG, replacing the natural butanoyl group at that position with an ester moiety terminating in a primary amine. Here, we describe our efforts to use transition metal cross-coupling reactions (Suzuki [10] and Heck [11]) to modify BHQ with a side chain terminating with a free primary amine

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• these conditions and form stable intermediates during this reaction that can further react. In a general procedure, C60Cl6 (200 mg, 0.21 mmol) and the primary amine of choice (8 equiv) are dissolved in a chlorobenzene/water mixture (8 mL/40 mL). The mixture is combined with the phase transfer agent

Efficient synthesis of pyrazolopyridines containing a chromane backbone through domino reaction

• Razieh Navari,
• Saeed Balalaie,
• Saber Mehrparvar,
• Fatemeh Darvish,
• Frank Rominger,
• Fatima Hamdan and
• Sattar Mirzaie

Beilstein J. Org. Chem. 2019, 15, 874–880, doi:10.3762/bjoc.15.85

• -one as a suitable Michael acceptor that can react with benzylamine or any primary amine to produce the intermediate A. There is a conjugated system in intermediate A that allows malononitrile to attack through Michael addition and produces the intermediate B (Scheme 2). Due to the presence of acidic

• molecules based on the pyrazolopyridine framework. ORTEP Structure of compound 4a and intermolecular hydrogen bonding; the ellipsoid probability level of each ORTEP diagram is 50%. Structures of synthesized pyrazolopyridines 4a–m. Reaction conditions: 3-formylchromone derivatives (1 mmol), primary amine

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• interesting to notice the presence in the mixture of dioxygenated products, the formation of which might be justified admitting the reaction of a primary amine group with a dibromide 4 unit and a CO2 molecule (likely absorbed from atmosphere) to afford a 1,3-oxazinan-2-one ring according to Scheme 4. The CO2

Synthesis and SAR of the antistaphylococcal natural product nematophin from Xenorhabdus nematophila

• Frank Wesche,
• Hélène Adihou,
• Thomas A. Wichelhaus and
• Helge B. Bode

Beilstein J. Org. Chem. 2019, 15, 535–541, doi:10.3762/bjoc.15.47

• aluminium chloride (AlCl3) in DCM to give compounds 14 and 21. Subsequent reduction was achieved with triethylsilane (Et3SiH) in TFA to give 15 and 22. For the synthesis of the primary amine, halides 15 and 22 were converted in a Gabriel synthesis with potassium phthalimide in DMF to the appropriate

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• moieties which protect the secondary amine of pteroate core as well as primary amine of ε-amino lysine residue. The N10-(trifluoroacetyl) or secondary amine protecting group of pteroic acid is selectively cleaved using 1% NH2NH2·H2O in DMF without affecting the trifluoroacetyl protecting group of lysine

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• ) using the conditions in entry 9 and a similar yield was obtained (Table 2, entry 11). When cyano compound 12 was reduced by hydrogenation in the presence of Raney-Ni as catalyst in NH3/CH3OH, the proposed primary amine 13 was obtained in 73% yield. Then, for the Mannich cyclization, when 13 was reacted

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

• areas of research, including colloid chemistry and interface science; nevertheless, the basic rules of organic chemistry should be regarded as playing a leading role in covalent functionalization. Review Reactions of carboxyl groups: amidation, esterification A primary amine or a primary alcohol

• (above 1700 cm−1) and a new absorption band in the wavenumber range of 1550 cm−1 to 1620 cm−1 can be directly inferred from the formation of either a hydrogen bond between primary amine and the carboxyl groups of GO or an inner salt formation (i.e., COO−NH3+). The presence of the amide bond in the

Asymmetric Michael addition reactions catalyzed by calix[4]thiourea cyclohexanediamine derivatives

• Zheng-Yi Li,
• Hong-Xiao Tong,
• Yuan Chen,
• Hong-Kui Su,
• Tangxin Xiao,
• Xiao-Qiang Sun and
• Leyong Wang

Beilstein J. Org. Chem. 2018, 14, 1901–1907, doi:10.3762/bjoc.14.164

• compound 6. Subsequently, different chiral cyclohexanediamine derivatives were reacted with calix[4]arene-based compound 6 to form the corresponding substituted thioureas. By this route the monosubstituted primary amine 1, monosubstituted tertiary amine 2 and disubstituted tertiary amine 3, respectively

• primary amine-containing catalyst 1 showed poor performance compared to the corresponding tertiary-amine containing catalysts 2 and 3. Although catalysts 2 and 3 demonstrated similar reactivities, we chose monosubstituted catalyst 2 as catalyst for further optimization according to the principle of atomic