Synthesis and reactivity of azole-based iodazinium salts

• Thomas J. Kuczmera,
• Annalena Dietz,
• Andreas Boelke and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2023, 19, 317–324, doi:10.3762/bjoc.19.27

• highly versatile, and a wide range of applications is meanwhile established in organic synthesis [1][2][3][4][5]. They can be applied as mild oxidants [6][7][8], in phenol dearomatizations [9] or in α-oxygenation reactions [10]. In a complemental reactivity, diaryliodonium salts are potent electrophilic

• potential in organic synthesis and catalysis, their structural variation is still limited. In particular, heteroarene-bridged cyclic iodonium salts are rare. Examples include the benzisoxazole-containing iodonium salt 1 described by Lisichkina and Tolstaya (Figure 1) [24][25]. Our group is interested in the

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

• turned into one of the most used and powerful reactions in organic synthesis, and allows the formation of functionalized double or triple bonds. Over the time, this reaction drew more and more scientists’ attention, with increasing numbers of publications on this topic [4][5][6]. Proof of this success

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• rearrangement [57]. Although, these protocols are useful and have exhibited wide applications in organic synthesis (Figure 2), the scope of these reported methods may suffer from drawbacks such as harsh reaction conditions, use of expensive reagents, prolonged reaction times, low product yields, and cumbersome

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

• Bram Ryckaert,
• Ellen Demeyere,
• Frederick Degroote,
• Hilde Janssens and
• Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

• 1,3-Dithianes are text book examples of versatile organic synthesis building blocks. They are familiar carbonyl protecting groups, but are more commonly known as ‘umpolung’ reagents, or acyl anion equivalents [1][2][3][4][5][6]. This is because they can be readily metalated and alkylated, allowing the

• ‘dithiane-scaffolding’ is indicated on the structures of the final targets. Compared to the very accomplished 1,3-dithianes, not many other sulfur-heterocycles have been able to follow into the mainstream organic synthesis tool box. For example, 1,3-dithiolanes are underperforming as heterocyclic building

• Downstream chemistry and further applications: deprotection, cleavage or further functionalization of 1,4-dithianes In organic synthesis, the deprotection of 1,3-dithianes has a reputation of being a troublesome reaction. In the chemical literature, there are probably well over a hundred distinct procedures

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

• reactions constitutes one of the main pillars of organic synthesis [1]. In this respect, the all-carbon Nazarov cyclization of divinyl ketones represents a direct method for the synthesis of five-membered carbocycles [2][3][4][5][6][7][8][9]. Variants of the Nazarov cyclization with substrates bearing one

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• advantage of circumventing the need for external redox additives and/or noble metals, using readily available and cost-effective NaI and PPh3 under mild reaction conditions. In a broader context, phosphine organocatalysis is probably still underappreciated in organic synthesis, and could lead to important

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• the perception that radicals cannot be selectively used took place with the introduction of tin hydrides in organic synthesis. Apart from the lower toxicity compared to organomercury reagents, the stability and longevity of tin-centered radicals allowed better propagation of radical chain reactions

• chemical libraries with natural scaffolds for biological screening. The evidenced increase of divergent radical syntheses in the last few years indicates that this approach is here to change the way chemists will practice total synthesis in the future. Evolution of radical chemistry for organic synthesis

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

• fit with the requisites of modern organic synthesis, as it requires over 40 steps to synthesize grayanotoxin II and was performed in racemic form (in the case of the formal synthesis), it represents an impressive piece of synthetic work. Achieving the synthesis of such a complex structure represented

• , advantages and drawbacks. The clear superiority of recent syntheses beautifully showcases the progresses in the field of organic synthesis over the last decades. Among the last three syntheses, Newhouse’s work has the huge advantage of being convergent, allowing a short synthesis (19 steps longest linear

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

• for organic synthesis and technology [1][2][3][4]. The importance of organocatalysis was acknowledged recently by the awarding of the Nobel Prize in chemistry to Benjamin List and David MacMillan, the leading researchers in this field. Selective oxidative transformations are crucially important for

• organic syntheses [5][6][7][8][9] and offer rich opportunities for the adaptation of organocatalysis. The diversity of such transformations spans from the functionalization of hydrocarbon raw materials to the fine organic synthesis, including functional group transformations, oxidative cyclizations, and

• oxidative coupling processes (also known as cross-dehydrogenative coupling), as well as late-stage CH-functionalization. Oxidation processes are recognized as a challenge in fine organic synthesis technology [10][11] due to selectivity problems and frequent need for toxic transition metal salts and

One-pot double annulations to confer diastereoselective spirooxindolepyrrolothiazoles

• Juan Lu,
• Bin Yao,
• Desheng Zhan,
• Zhuo Sun,
• Yun Ji and
• Xiaofeng Zhang

Beilstein J. Org. Chem. 2022, 18, 1607–1616, doi:10.3762/bjoc.18.171

• ]. Pyrrolothiazole and spirooxindole moieties occupy exclusive positions as valuable source of natural products and therapeutic agents in organic synthesis and drug discovery [60][61][62][63][64][65][66][67][68]. We have developed a number of asymmetric reactions to construct spirooxindole-based scaffolds through

New triazole-substituted triterpene derivatives exhibiting anti-RSV activity: synthesis, biological evaluation, and molecular modeling

• Elenilson F. da Silva,
• Krist Helen Antunes Fernandes,
• Denise Diedrich,
• Jessica Gotardi,
• Marcia Silvana Freire Franco,
• Carlos Henrique Tomich de Paula da Silva,
• Ana Paula Duarte de Souza and
• Simone Cristina Baggio Gnoatto

Beilstein J. Org. Chem. 2022, 18, 1524–1531, doi:10.3762/bjoc.18.161

• Elenilson F. da Silva Krist Helen Antunes Fernandes Denise Diedrich Jessica Gotardi Marcia Silvana Freire Franco Carlos Henrique Tomich de Paula da Silva Ana Paula Duarte de Souza Simone Cristina Baggio Gnoatto Phytochemistry and Organic Synthesis Laboratory, School of Pharmacy, Federal University

One-pot synthesis of 2-arylated and 2-alkylated benzoxazoles and benzimidazoles based on triphenylbismuth dichloride-promoted desulfurization of thioamides

• Arisu Koyanagi,
• Yuki Murata,
• Shiori Hayakawa,
• Mio Matsumura and
• Shuji Yasuike

Beilstein J. Org. Chem. 2022, 18, 1479–1487, doi:10.3762/bjoc.18.155

• , the need for bases, and limited substrate scope. With the development of organobismuth chemistry, these compounds have been applied in various areas of science including biology and organic synthesis because they are normally non-toxic and exhibit unique biological activities [13][14][15][16][17][18

On drug discovery against infectious diseases and academic medicinal chemistry contributions

• Yves L. Janin

Beilstein J. Org. Chem. 2022, 18, 1355–1378, doi:10.3762/bjoc.18.141

• of work. Then, the necessary feedback from the assays along with quite a few controls and further evaluations (i.e., from ligand binding thermodynamics, if the target is known, to cellular toxicity and all the way to early ADME) will also take some time. In other words, organic synthesis remains one

• and the following suggestions are only additions to the far more thorough reviews describing recent contribution of organic synthesis to drug discovery [254][255][256][257]. A report [258] surveying the most used reactions in medicinal chemistry is also of relevance; although whether these emerged

B–N/B–H Transborylation: borane-catalysed nitrile hydroboration

• Filip Meger,
• Alexander C. W. Kwok,
• Franziska Gilch,
• Dominic R. Willcox,
• Alex J. Hendy,
• Kieran Nicholson,
• Andrew D. Bage,
• Thomas Langer,
• Thomas A. Hunt and
• Stephen P. Thomas

Beilstein J. Org. Chem. 2022, 18, 1332–1337, doi:10.3762/bjoc.18.138

• , Chemical Development U.K., AstraZeneca, Macclesfield, SK10 2NA, United Kingdom Medicinal Chemistry, Early Oncology, AstraZeneca, Cambridge, CB4 0WG, United Kingdom 10.3762/bjoc.18.138 Abstract The reduction of nitriles to primary amines is a useful transformation in organic synthesis, however, it often

• of a double B–N/B–H transborylation mechanism. Keywords: boron; catalysis; hydroboration; nitrile; transborylation; Introduction Primary amines are prevalent throughout organic synthesis, finding regular application in materials chemistry, pharmaceuticals, and agrochemicals (Scheme 1a) [1][2][3

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• pharmaceutical activities such as antimicrobial [2][3], antiviral [4], antitumor [5][6], anti-inflammatory [7][8] and so on. Moreover, as a type of important intermediates, thiazole is of prime importance in organic synthesis [9][10] which is used extensively in the preparation of flavors [11], polymers [12

From amines to (form)amides: a simple and successful mechanochemical approach

• Federico Casti,
• Rita Mocci and
• Andrea Porcheddu

Beilstein J. Org. Chem. 2022, 18, 1210–1216, doi:10.3762/bjoc.18.126

• amines plays a crucial role in organic synthesis [1][2][3][4][5][6]. In one respect, it is relevant to protect the amine group straightforwardly and under mild conditions [7][8]. On the other hand, the formamide and acetamide moieties are found in many active pharmaceutical ingredients (APIs) and natural

Reductive opening of a cyclopropane ring in the Ni(II) coordination environment: a route to functionalized dehydroalanine and cysteine derivatives

• Oleg A. Levitskiy,
• Olga I. Aglamazova,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2022, 18, 1166–1176, doi:10.3762/bjoc.18.121

• base complexes; stereoselective electrosynthesis; voltammetric testing; Introduction Electrochemistry provides a direct access to highly reactive species by means of harnessing electrons or electron holes as reagents [1][2]. This capacity can be efficiently exploited in organic synthesis for rational

• ][40][41][42]. The principal possibility of the process was demonstrated but the synthetic potential of the method was not sufficiently implemented. Great success of the donor–acceptor cyclopropane concept in organic synthesis stimulated a renaissance of interest to electrochemical ring opening. Quite

Electro-conversion of cumene into acetophenone using boron-doped diamond electrodes

• Mana Kitano,
• Tsuyoshi Saitoh,
• Shigeru Nishiyama,
• Yasuaki Einaga and
• Takashi Yamamoto

Beilstein J. Org. Chem. 2022, 18, 1154–1158, doi:10.3762/bjoc.18.119

• , first reported in 1944 [3], a wide variety of catalytic systems are still being reported [4][5][6][7][8][9][10][11][12]. Electro-organic synthesis refers to an organic synthetic method combined with electrochemistry [13][14]. A striking feature in electro-organic synthesis is the use of electricity as a

• reagent, which allows to reduce the reagent waste to a minimum. Obviously, as this characteristic matches well with the increasing demands to realize a sustainable society. In electro-organic synthesis, electrode materials are one of the most significant parameters because reactions occur at the anode and

Experimental and theoretical studies on the synthesis of 1,4,5-trisubstituted pyrrolidine-2,3-diones

• Nguyen Tran Nguyen,
• Vo Viet Dai,
• Nguyen Ngoc Tri,
• Luc Van Meervelt,
• Nguyen Tien Trung and
• Wim Dehaen

Beilstein J. Org. Chem. 2022, 18, 1140–1153, doi:10.3762/bjoc.18.118

• form doxapram hydrochloride which helps to increase the respiratory rate [7] (Figure 1). Among the 2-pyrrolidinone derivatives, 1,5-dihydro-2H-pyrrol-2-ones, also named as 3-pyrrolin-2-ones, are important builiding blocks which can be further modified in organic synthesis and medicinal chemistry [8][9

• , additional DFT data and NMR spectra. Acknowledgements We would like to thank Prof. Wim De Borggraeve and Ph.D. researcher Ruben Van Lommel, Laboratory of Organic Synthesis, KU Leuven, Belgium, for comments on structure of compounds via NMR measurements. Funding This research was financially supported by

Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor

• Wei-Hsin Hsu,
• Susanne Reischauer,
• Peter H. Seeberger,
• Bartholomäus Pieber and
• Dario Cambié

Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115

• ; heterogeneous catalysis; metallaphotoredox catalysis; packed bed; photochemistry; Introduction The amount and impact of visible-light-mediated protocols in organic synthesis have increased dramatically since the late 2000s [1]. The main driving force of this phenomenon is the novel reactivity afforded by

• [4][5]. This is underlined by several photochemical and photocatalytic transformations that have been performed on industrial scales in continuous-flow reactors [6][7][8]. A particularly appealing branch of photocatalytic organic synthesis is the combination with other modes of catalysis in dual

• visible-light photocatalysts that enable new reaction pathways that were previously difficult or impossible to realize [2]. Technical advancements, such as the rise of light-emitting diodes (LEDs) and new reactor technologies were similarly important incentives to popularize light-mediated organic

Electrogenerated base-promoted cyclopropanation using alkyl 2-chloroacetates

• Kouichi Matsumoto,
• Yuta Hayashi,
• Kengo Hamasaki,
• Mizuki Matsuse,
• Hiyono Suzuki,
• Keiji Nishiwaki and
• Norihito Kawashita

Beilstein J. Org. Chem. 2022, 18, 1116–1122, doi:10.3762/bjoc.18.114

• organic synthesis as versatile building blocks [1][2][3][4][5]. In general, some synthetic procedures for cyclopropane derivatives have been discovered, e.g., the Simmons–Smith reaction and the use of metal carbenoids being two of the more prominent and reliable methods [6][7][8][9]. Aggarwal and

Electrochemical hydrogenation of enones using a proton-exchange membrane reactor: selectivity and utility

• Koichi Mitsudo,
• Haruka Inoue,
• Yuta Niki,
• Eisuke Sato and
• Seiji Suga

Beilstein J. Org. Chem. 2022, 18, 1055–1061, doi:10.3762/bjoc.18.107

• reactor; Introduction Catalytic hydrogenation of α,β-enones is a significant transformation in organic synthesis [1]. Hydrogenation of enones can give ketones, allyl alcohols, and saturated alcohols, and the control of the chemoselectivity is important. Therefore, there have been numerous studies on the

• environmentally benign organic transformations. Despite these advantages, the utility of PEM reactors in precise organic synthesis has long been unclear. Recently, however, Atobe and co-workers showed that PEM reactors can be used as a powerful and novel tool for precise organic synthesis [22][23][24][25][26

Electrochemical Friedel–Crafts-type amidomethylation of arenes by a novel electrochemical oxidation system using a quasi-divided cell and trialkylammonium tetrafluoroborate

• Hisanori Senboku,
• Mizuki Hayama and
• Hidetoshi Matsuno

Beilstein J. Org. Chem. 2022, 18, 1040–1046, doi:10.3762/bjoc.18.105

• in organic synthesis and sometimes appear in biologically active compounds, pharmaceuticals, agrochemicals and functional molecules, amidomethylation induced by N-acyliminium ions is a helpful and valuable protocol for direct introduction of an amide function into organic molecules. Generation of N

• has also been applied to organic synthesis [17][18][19][20]. However, when electrochemical oxidation of amides/carbamates in the presence of nucleophiles, such as electron-rich arenes or silyl enol ethers, is carried out for Friedel–Crafts-type amidomethylation, electrochemical oxidation of electron

• amidomethylated products in good to high yields. Keywords: electrochemical oxidation; Friedel–Crafts type amidomethylation; N-acyliminium ion; quasi-divided cell; trialkylammonium salt; Introduction Oxidation of amides generates useful intermediates, N-acyliminium ions, which have been widely used in organic

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

• Yi-Lun Li,
• Zhaojiang Shi,
• Tao Shen and
• Ke-Yin Ye

Beilstein J. Org. Chem. 2022, 18, 1026–1031, doi:10.3762/bjoc.18.103

• ; Introduction Organoazides play important roles in pharmaceutical, bioorthogonal chemistry, and many other interdisciplinary research areas [1][2][3]. Among them, azidoketones are also very versatile building blocks in organic synthesis, pharmaceutical, and materials science [4][5][6]. Therefore, the

First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell

• Daniele Rocco,
• Ana A. Folgueiras-Amador,
• Richard C. D. Brown and
• Marta Feroci

Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98

• scale up. In the case of the flow procedure, a 0.1 M solution of the IL is employed, which may be more convenient than using pure ILs. Further investigations of electrogeneration of NHCs and applications in organic synthesis are underway. Experimental Materials and methods Chemicals were purchased from