Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• -mn]acridones has been worked out. Keywords: alkaloids; cyclization; metalation; naphthyridine; pyridoacridine; Introduction Polycyclic aromatic alkaloids are a unique class of natural products with a broad pattern of biological activities. One of the most prominent classes are the so-called

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

• Sara Peeters,
• Linn Neerbye Berntsen,
• Pål Rongved and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2019, 15, 2156–2160, doi:10.3762/bjoc.15.212

• compounds with biological activities ranging from antitumor, antiviral, antibiotic and antiparasitic to cannabinoid receptor modulating [22][23][24][25][26][27][28]. Despite the attractive features of the quinolone-3-carboxylate scaffold, there are only four reported routes towards this valuable structural

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• . Keywords: benzimidazole; cesium carbonate; cyclization; selenium; selenoazole; Introduction Selenium-containing heterocyclic ring systems have attracted attention not only because of their chemical properties and reactivities, but also for their wide biological activities [1][2][3][4]. For example

Bipolenins K–N: New sesquiterpenoids from the fungal plant pathogen Bipolaris sorokiniana

• Chin-Soon Phan,
• Hang Li,
• Simon Kessler,
• Peter S. Solomon,
• Andrew M. Piggott and
• Yit-Heng Chooi

Beilstein J. Org. Chem. 2019, 15, 2020–2028, doi:10.3762/bjoc.15.198

• aldehyde moiety in 7. Interestingly, an earlier study showed that 7 promoted the elongation of the shoots of rice seedlings [20]. Compound 12 was reported to have a broad spectrum of biological activities, including phytotoxicity on juvenile plant Bromus tectorum [21], syncytium formation inhibitory

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• and multiple promising biological activities. In this review, progress in the total syntheses of triptolide are systematically summarized. We hope to gain a better understanding of the field and provide constructive suggestions for future studies of triptolide. Keywords: total synthesis; Tripterygium

• treatment of rheumatoid arthritis (RA) [31], systemic lupus erythematosus (SLE) and skin allograft rejection [32]. Despite the promising biological activities of triptolide, the narrow therapeutic window and multi-organ toxicity hindered greatly its clinical progress. Reports have shown that triptolide

• furnish the trans-decalin A/B ring system. Conclusion and Future Perspectives Taken together, the intriguing structural features, the promising multiple biological activities and the lack of natural sources have made triptolide an attractive target for total synthesis. So far, lots of total syntheses and

Reactions of 2-carbonyl- and 2-hydroxy(or methoxy)alkyl-substituted benzimidazoles with arenes in the superacid CF₃SO₃H. NMR and DFT studies of dicationic electrophilic species

• Dmitry S. Ryabukhin,
• Alexey N. Turdakov,
• Natalia S. Soldatova,
• Mikhail O. Kompanets,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1962–1973, doi:10.3762/bjoc.15.191

• biological activities including antiparasitic (albendazole, mebendazole), antiulcer (omeprazole), antihypertensive (candesartan, telmisartan, azilsartan, medoxomil, mebefradil), anticancer (bendamustine), antiemetic/antipsychotic (droperidole), antihistaminic (astemizole, emedastine) and many others (Figure

A golden opportunity: benzofuranone modifications of aurones and their influence on optical properties, toxicity, and potential as dyes

• Joza Schmitt and
• Scott T. Handy

Beilstein J. Org. Chem. 2019, 15, 1781–1785, doi:10.3762/bjoc.15.171

• of snapdragons and cosmos. Most studies of aurones focus on their range of biological activities, but relatively little has been reported with respect to their optical properties, unlike their aza and thio analogs. What little is known has focused entirely on the influence of the benzylidene portion

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• natural products as well as compounds of commercial interest as medications. Synthetic strategies to molecules as simple as amino alcohols to as complex as indolizine alkaloids will be discussed with a special focus on stereoselectivities of key transformations. Whenever possible biological activities of

• biological activities [106]. (−)-Dihydropinidine (2S,6R)-187a, isosolenopsin (2S,6R)-187b, and isosolenopsins A (2S,6R)-187c and B (2S,6R)-187d were synthesized as hydrochloride salts from the aldehyde (2S,1'R)-6 applying a reductive amination as a key step (Scheme 50) [33]. To this end the aldehyde (2S,1'R

• (+)-deoxocassine ((2S,3S,6R)-190a) and (+)-spectaline ((2S,3S,6R)-190b) as already described. (+)-Microgrewiapine A ((2R,3S,6R)-194a) [107] and (+)-microcosamine A ((2R,3S,6R)-194b) [108] have recently been isolated and exhibited interesting biological activities, for example cytotoxicity [107]. The total

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

A heteroditopic macrocycle as organocatalytic nanoreactor for pyrroloacridinone synthesis in water

• Piyali Sarkar,
• Sayan Sarkar and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2019, 15, 1505–1514, doi:10.3762/bjoc.15.152

• ; pyrroloacridinones; sustainable chemistry; water; Introduction Acridines are a renowned heterocyclic entity not only for their biological activities but also for their fluorescence and chemiluminescence properties. Acridine dyes (e.g., acridine orange, acridine yellow, etc.), are predominantly used in staining of

Synthesis and biological evaluation of truncated derivatives of abyssomicin C as antibacterial agents

• Leticia Monjas,
• Peter Fodran,
• Johanna Kollback,
• Carlo Cassani,
• Thomas Olsson,
• Maja Genheden,
• D. G. Joakim Larsson and
• Carl-Johan Wallentin

Beilstein J. Org. Chem. 2019, 15, 1468–1474, doi:10.3762/bjoc.15.147

• -abyssomicin C with their biological activities, and the truncated derivatives 1 and 2. In red: part of abyssomicin C that is maintained in the truncated derivatives [4][7][8][9][10]. A) Docking poses for atrop-O-benzyl-desmethyl-abyssomicin C (orange) and compound 2 (green) showing key interactions and

Formation of an unexpected 3,3-diphenyl-3H-indazole through a facile intramolecular [2 + 3] cycloaddition of the diazo intermediate

• Andrew T. King,
• Hugh G. Hiscocks,
• Lidia Matesic,
• Mohan Bhadbhade,
• Roger Bishop and
• Alison T. Ung

Beilstein J. Org. Chem. 2019, 15, 1347–1354, doi:10.3762/bjoc.15.134

• unfamiliarity, the C–H···H–C contacts illustrated in Figure 6 are similarly attractive in nature. Proposed mechanism for the formation of 8 Indazoles are well-recognised for their important biological activities. They are known to be used as building blocks in drug development. A review by Gaikwad et al

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides

• Madhu Babu Tatina,
• Xia Mengxin,
• Rao Peilin and
• Zaher M. A. Judeh

Beilstein J. Org. Chem. 2019, 15, 1275–1280, doi:10.3762/bjoc.15.125

• ; pseudo-glycosides; Introduction 2,3-Unsaturated glycosides, also known as pseudo-glycosides or enosides, are an important class of natural products with many biological activities and capacity to serve as substrates for further reactions [1][2][3]. They are involved in biochemical processes such as

Steroid diversification by multicomponent reactions

• Leslie Reguera,
• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Daniel G. Rivera

Beilstein J. Org. Chem. 2019, 15, 1236–1256, doi:10.3762/bjoc.15.121

• displaying biological activities such as antimicrobial, antiviral and anti-inflammatory, among others. Scheme 3 exemplifies the reaction of cholestan-6-one 7 with 2-aminopyridine and phenyl isocyanide to afford the heterocycle–steroid hybrid 8 in good yield and diastereoselectivity, whereas different

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

• Herman O. Sintim,
• Hamad H. Al Mamari,
• Hasanain A. A. Almohseni,
• Younes Fegheh-Hassanpour and
• David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

• ., squalestatin S1/zaragozic acid A (1), Figure 1) have been of enduring interest to synthetic chemists, due to a combination of a synthetically challenging densely functionalised 2,8-dioxabicyclo[3.2.1]octane core [3][4][5][6], combined with an increasing range of intriguing biological activities [7][8][9][10

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

• derivatives show a large variety of biological activities [21][22][23], such as COX-2 inhibition [24], glucokinase activation [25], sodium channel blocking [26], antimycobacterial [27], antiproliferative [28] or carbonic anhydrase inhibition [29], as well as antifungal and antibacterial properties [30

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• stereogenic centers in a one-step [4 + 2] cycloaddition or cyclization reaction [6][7][8] and it has become hugely popular in preparing vital intermediates for the syntheses of key structural subunits of natural products with biological activities (e.g., carbohydrates, antibiotics, toxins etc.) [9][10

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

• found to exhibit a broad range of biological activities [11][12][13]. 3-Formylchromone was used as a suitable starting material for the construction of various heterocyclic skeletons [14][15][16][17]. Pyrazolopyridines are a promising class of heterocyclic compounds which inhibits cyclin-dependent

• workup procedures, and several side reactions with less selectivity of the process. Due to the extended biological activities of pyrazolopyridines, finding a suitable approach for the synthesis of these compounds is a synthetic challenge in organic synthesis. In continuation of our research work to

Synthesis of a novel category of pseudo-peptides using an Ugi three-component reaction of levulinic acid as bifunctional substrate, amines, and amino acid-based isocyanides

• Maryam Khalesi,
• Azim Ziyaei Halimehjani and
• Jürgen Martens

Beilstein J. Org. Chem. 2019, 15, 852–857, doi:10.3762/bjoc.15.82

• -component reaction. The main advantage of this paper refers to the application of three amino acid-based isocyanides in the reaction with levulinic acid as a bifunctional substrate and amines which led to the formation of novel peptidomimetics with potential biological activities. In addition, the presence

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

• good yields and excellent chemical purity without requiring column chromatographical purification. Keywords: 2-amino-4H-benzothiopyran-4-ones; addition–elimination; scale-up synthesis; sulfinyl group; Introduction Benzothiopyranones are a class of molecules displaying biological activities in part

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

• ; Introduction Purine [1][2][3][4][5][6][7] and 7-deazapurine (IUPAC name: pyrrolo[2,3-d]pyrimidine) [8][9][10][11] derivatives have been progressively studied for decades due to their wide range of biological activities and photophysical properties. Currently, the synthesis of push–pull systems is a promising

Study on the regioselectivity of the N-ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide

• Pedro N. Batalha,
• Luana da S. M. Forezi,
• Maria Clara R. Freitas,
• Nathalia M. de C. Tolentino,
• Ednilsom Orestes,
• José Walkimar de M. Carneiro,
• Fernanda da C. S. Boechat and
• Maria Cecília B. V. de Souza

Beilstein J. Org. Chem. 2019, 15, 388–400, doi:10.3762/bjoc.15.35

• antibacterial and antiviral. The presence of a carboxamide unit connected to carbon C-3 of the 4-oxoquinoline core has been associated with various biological activities. Experimentally, the N-ethylation reaction of N-benzyl-4-oxo-1,4-dihydroquinoline-3-carboxamide occurs at the nitrogen of the oxoquinoline

Annulation of 1H-pyrrole-2,3-diones by thioacetamide: an approach to 5-azaisatins

• Aleksandr I. Kobelev,
• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2019, 15, 364–370, doi:10.3762/bjoc.15.32

• which are in great request in medicinal chemistry as they exhibit a variety of biological activities [2][3][4][5][6][7][8][9]. 5-Azaisatins (1H-pyrrolo[3,2-c]pyridine-2,3-diones) are a useful but sparingly studied kind of isatin’s aza isosteres [10][11][12][13][14][15][16]. Presently, few synthetic

A novel and efficient synthesis of phenanthrene derivatives via palladium/norbornadiene-catalyzed domino one-pot reaction

• Yue Zhong,
• Wen-Yu Wu,
• Shao-Peng Yu,
• Tian-Yuan Fan,
• Hai-Tao Yu,
• Nian-Guang Li,
• Zhi-Hao Shi,
• Yu-Ping Tang and
• Jin-Ao Duan

Beilstein J. Org. Chem. 2019, 15, 291–298, doi:10.3762/bjoc.15.26

• used as fundamental building blocks or intermediates in the synthesis of complex natural products such as tuberosinone [1], aristolactam Ia [2] and (−)-R-tylophorine [3] (Figure 1). Meanwhile, they also demonstrate a wide range of biological activities including anticancer [4], anti-HIV [5

Metal-free C–H mercaptalization of benzothiazoles and benzoxazoles using 1,3-propanedithiol as thiol source

• Yan Xiao,
• Bing Jing,
• Xiaoxia Liu,
• Hongyu Xue and
• Yajun Liu

Beilstein J. Org. Chem. 2019, 15, 279–284, doi:10.3762/bjoc.15.24

• -mercaptobenzoxazoles are not only fundamental building blocks in organic synthesis, but also possess various biological activities (Figure 1) [1][2]. A complex of a transition metal (such as Ru, Pt, Bi, etc.) with either a 2-mercaptobenzoxazole or a 2-mercaptobenzothiazole often provides cytotoxic activity against