Recent advancements in iodide/phosphine-mediated photoredox radical reactions

• Tinglan Liu,
• Yu Zhou,
• Junhong Tang and
• Chengming Wang

Beilstein J. Org. Chem. 2023, 19, 1785–1803, doi:10.3762/bjoc.19.131

• the ability to be readily transformed into various valuable functional molecules, including amines, hydrazines, and nitrogen-containing heterocycles [13]. In a significant advancement in 2021, Lopchuk et al. revealed a novel method for the photodecarboxylative alkylation of diazirines 12 using the

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

• of the product, while benzoyl peroxide (BPO) gave a low yield. Various nucleophiles 161, including ammonia, alkylamines, hydrazines, alcohols and alkoxides, indole, N-alkylpyrrole, N-substituted anilines, PhSH, and PhMgBr worked well under these conditions. Asymmetric thiolation of 4-substituted

Cyanothioacetamides as a synthetic platform for the synthesis of aminopyrazole derivatives

• Valeriy O. Filimonov,
• Alexandra I. Topchiy,
• Vladimir G. Ilkin,
• Tetyana V. Beryozkina and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2023, 19, 1191–1197, doi:10.3762/bjoc.19.87

• pyrazoles has been thus synthesized. The structure of the reaction products was studied using NMR spectroscopy and mass spectrometry and confirmed by X-ray diffraction analysis. Keywords: aminopyrazoles; 2-cyanothioacetamides; enamines; hydrazines; Introduction Compounds containing a pyrazole cycle

• -(substituted)phenylsulfonyl-4-thiocarbamoylpyrazoles in moderate to high yields. It was concluded that in 2-cyanothioacetamides, cyano and enamino groups are more active in the reaction with hydrazines than the thiocarbamoyl function. Experimental X-ray structure determination of 5b, 6a, 7a 5b: Crystal data

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• ). Alternatively, removal of Boc groups could be performed by treatment with aqueous HCl to give the corresponding hydrochloride salts, which could be converted into free hydrazines by treatment with excess NaHCO3 in ethanol (as demonstrated for product 19c). Note that TAADs 19–21 with free amino groups are more

A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines

• Greta Utecht-Jarzyńska,
• Karolina Nagła,
• Grzegorz Mlostoń,
• Heinz Heimgartner,
• Marcin Palusiak and
• Marcin Jasiński

Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108

• hydrazines in a closed ampoule at 75 °C in methanol in the presence of molecular sieves (4 Å) [46]. General procedure To a stirred solution of the respective 1,4-quinone 1 (1.0 mmol) and K2CO3 in dry THF (10 mL), a hydrazonoyl bromide 8 (1.1 mmol) was added, and stirring was continued at room temperature

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

Hydrazides in the reaction with hydroxypyrrolines: less nucleophilicity – more diversity

• Dmitrii A. Shabalin,
• Evgeniya E. Ivanova,
• Igor A. Ushakov,
• Elena Yu. Schmidt and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2021, 17, 319–324, doi:10.3762/bjoc.17.29

• ][9] or calcium carbide [10]) with hydrazines (Scheme 1) [11][12]. The reaction is operationally simple and tolerates a wide range of hydrazines including alkyl-, aryl-, and hetarylhydrazines [11] as well as semicarbazide and its derivatives [12]. However, the scope of this method with a special

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

• ][45][46][47]. Moreover, arylhydrazones and arylhydrazines/hydrazines can be used as well, respectively, as partners in [4 + 2] cyclization reactions [48][49][50][51] or by reacting mostly with carbonyl derivatives [52][53][54][55]. From the state-of-the-art, a strategy that promotes the synthesis of

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• developed, starting from sulfonyl hydrazines in place of sulfonyl chlorides. In this case, the RuII-based photocatalyst was able to reduce tert-butyl peroxybenzoate, triggering the release of a tert-butoxyl radical. This was in turn able to oxidize the hydrazine, allowing the liberation of the desired

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• -workers exploited the copper-catalysed asymmetric ring opening of polycyclic meso hydrazines with organoaluminium reagents (Scheme 13) [43]. This reaction followed a classical allylic substitution pathway. Interestingly, the organoaluminium reagents in this reaction did not only act as alkyl donors but

• oxabicyclic substrates with organolithium reagents (selected examples). Copper-catalysed ring opening of polycyclic meso hydrazines. Copper-catalysed ACA of Grignard reagents to alkenyl-substituted aromatic N-heterocycles. Copper-catalysed ACA of Grignard reagents to β-substituted alkenylpyridines. Copper

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

• Tobias Lucas,
• Jule-Philipp Dietz and
• Till Opatz

Beilstein J. Org. Chem. 2020, 16, 445–450, doi:10.3762/bjoc.16.41

• the formation of fluorinated heterocycles. While attempts to obtain an aminooxazole upon reaction with hydroxylamine were unsuccessful, substituted hydrazines turned out to provide moderate yields of fluorinated pyrazoles. Phenylhydrazine (12a) was chosen as the model substrate for optimization (Table

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• -(2-iodoaryl)acrylamides 113, DABCO·(SO2)2 (69) and hydrazines 114. Proposed mechanism for the preparation of oxindoles 115. Three-component reaction of acrylamide 113, CO (23) and 1,4-benzodiazepine 121. Multicomponent reaction of sulfonylacrylamides 123, aryldiazonium tetrafluoroborates 68 and DABCO

Azologization of serotonin 5-HT₃ receptor antagonists

• Karin Rustler,
• Galyna Maleeva,
• Piotr Bregestovski and
• Burkhard König

Beilstein J. Org. Chem. 2019, 15, 780–788, doi:10.3762/bjoc.15.74

• photochromic derivatives with varying electronic and thus photochromic properties. The respective arylamines 13a–c were converted into their corresponding hydrazines 14a–c via diazonium-salt formation using sodium nitrite and subsequent reduction using tin(II) chloride [70]. The following nucleophilic

Microwave-assisted synthesis of biologically relevant steroidal 17-exo-pyrazol-5'-ones from a norpregnene precursor by a side-chain elongation/heterocyclization sequence

• Gergő Mótyán,
• László Mérai,
• Márton Attila Kiss,
• Zsuzsanna Schelz,
• Izabella Sinka,
• István Zupkó and
• Éva Frank

Beilstein J. Org. Chem. 2018, 14, 2589–2596, doi:10.3762/bjoc.14.236

• of interest from a pharmacological point of view. The first and probably most frequently used method for the synthesis of pyrazolones is based on the Knorr condensation of β-ketoesters with substituted or unsubstituted hydrazines. However, these reactions often suffer from certain disadvantages, such

• preliminary results concerning the cancer selectivity of the selected agents. Results and Discussion Synthetic studies The steroidal β-ketoester precursor 4, suitable for the attempted heterocyclization reaction with hydrazines was synthesized from commercially available pregnenolone acetate (1) via a

• magnesium enolate. Although the presence of a C16–C17 double bond as in 4' is assumed to be beneficial for a P45017α-inhibitory effect, further transformations of this compound were abandoned because of the insufficient yield and its potential tendency to react with monosubstituted hydrazines – not only

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• treat schizophrenia. In an interesting report Aggarwal et al. [74] described the synthesis of 4,7-dihydropyrazolo[3,4-b]pyridine-5-nitriles 92 from the reaction of β-ketonitriles 15 with several aryl/heteroaryl hydrazines 14 in ethanol with a catalytic amount of conc. HNO3 (Scheme 26). The authors

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• )–H with a electrophilic trifluoromethylation reagent (Togni’s reagent): N,N-Dialkylhydrazones were widely used in organic chemistry, including using as synthetic equivalents of carbonyl compounds, as precursors to substituted hydrazines or primary amines. In 2013, Baudoin and co-workers [53] firstly

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• disulfide, thioamide derivatives and sulfides Disulfides and thiosulfates Sulfoxides Sulfinic acids, sulfinate salts and sulfinamides Sulfonyl halides, sulfonyl hydrazines, thionyl chloride and sulfur dioxide C–S bond formations initiated by irradiation with light of wavelengths shorter than 380 nm or by

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• nucleophile then attacks the β-position of the vinylphosphonium salt 64, resulting in the expected resonance-stabilized ylide 65 [62]. The corresponding ylides 66 were also obtained in high yields of 90–94% in an analogous reaction by the use of aryl hydrazines (Scheme 43) [62]. The same type of reaction but

• phosphorus ylides via the reaction of triphenylphosphine with dialkyl acetylenedicarboxylates and arylsulfonic hydrazides. Synthesis of resonance-stabilized phosphorus ylides in the reaction of triphenylphosphine, dialkyl acetylenedicarboxylates, and aryl hydrazines. Synthesis of resonance-stabilized

A concise flow synthesis of indole-3-carboxylic ester and its derivatisation to an auxin mimic

• Marcus Baumann,
• Ian R. Baxendale and
• Fabien Deplante

Beilstein J. Org. Chem. 2017, 13, 2549–2560, doi:10.3762/bjoc.13.251

• new entries into these valuable structures [6]. However, common to the majority of these indole syntheses is the use of hazardous entities such as hydrazines (Fischer), diazonium species (Japp–Klingemann) or azides (Hemetsberger–Knittel) or the necessity to construct specifically functionalised

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• dicyanofumarates E-1 with 1-azabicyclo[1.1.0]butanes 55. Formation of pyrazole derivatives in the reaction of hydrazines with E-1. Formation of 5-aminopyrazole-3,4-dicarboxylate 65 via heterocyclization reactions. Reactions of aryl- and hetarylcarbohydrazides 67 with E-1a. Multistep reaction leading to

Transition-metal-free synthesis of 3-sulfenylated chromones via KIO₃-catalyzed radical C(sp²)–H sulfenylation

• Yanhui Guo,
• Shanshan Zhong,
• Li Wei and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2017, 13, 2017–2022, doi:10.3762/bjoc.13.199

• Yanhui Guo Shanshan Zhong Li Wei Jie-Ping Wan College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, P.R. China 10.3762/bjoc.13.199 Abstract The reactions between o-hydroxylphenyl-functionalized enaminones and sulfonyl hydrazines providing 3-sulfenylated

• protocol toward these compounds through the tandem reactions between o-hydroxyphenylenaminones and sulfonyl hydrazines. In this method, the construction of the target products is furnished via the key C–H sulfenylation without using any transition metal catalyst or oxidative additive. Results and

• ), prolonging the reaction time to 24 h was found to be capable of further improving the yield of 3a (entries 16 and 17, Table 1). To examine the scope of the reaction, enaminones 1 containing different functional groups as well as various sulfonyl hydrazines 2 were subjected to the optimized standard reaction

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

• Josef Jansa,
• Ramona Schmidt,
• Ashenafi Damtew Mamuye,
• Laura Castoldi,
• Alexander Roller,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2017, 13, 895–902, doi:10.3762/bjoc.13.90

• most common strategies employ reactions of 1,3-dicarbonyl compounds or α,β-unsaturated carbonyl compounds with substituted hydrazines [4][6][19]. To overcome the drawbacks of this method, namely insufficient regioselectivity [20], other accesses such as, for instance, regioselective metalations of N

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• alcohol. The diacyl hydrazines 14b,c were obtained through the coupling of the hydrazide derivatives 13b,c with carboxylic acids 12b,c in the presence of N,N'-dicyclohexylcarbodiimide (DCC) as reported earlier [18]. A modified procedure, which avoids the preparation of hydrazides 13, was used for the

• the obtained diacylated hydrazines 14b–g were in the range of 58–74% (Scheme 3). Finally, heating the diacyl hydrazines 14b–g in phosphorus oxychloride led to the formation of the desired 1,3,4-oxadiazoles 15b–g. The product yields were between 65–94% after purification by column chromatography

• -carboxylic acids 7d–g. Synthesis of diacyl hydrazines 14b–g. Synthesis of 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles 15b–g. Reaction conditions and yields for the synthesis of ethyl 5'-aryl-3-decyl-2,2'-bithiophene-5-carboxylates 7d–g. Spectroscopic and luminescent properties