Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• by pqs QS, pyocyanin is one of the most prominent. This redox-active pigment is responsible for the greenish-blueish colour of P. aeruginosa cultures. It seems that generation of reactive oxygen species is a major mechanism of pyocyanin cytotoxicity [41]. This tricyclic compound is known to induce

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• ; propellane; ring-closing metathesis; Introduction In 1966 Ginsburg coined the word “propellane” [1][2] and Wiberg reviewed various aspects of medium and small ring propellanes [3][4]. Propellanes consist of tricyclic compounds where three rings are conjoined by a common C–C bond [1][5][6]. Heterocyclic

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• . Structure–activity relationship studies have indicated that the 2-methyl and 3-acetic acid residues are crucial to maintaining the potency of this scaffold [10]. The Boehringer Ingelheim chemical development route toward the synthesis of quinoline 1 is shown in Scheme 1 [11]. The northern tricyclic

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• the CF2CF2 unit between two cyclohexane rings caused significant enhancement in thermal stability in a liquid crystalline phase (Figure 1c) [11]. In addition to the development of a convenient access to CF2CF2-containing pyranoses [12], our group also showed that tricyclic mesogens with a CF2CF2

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

• Mannich reaction to construct the tricyclic framework of 6. The study started with the alkylation under catalysis of 3 in a two-phase system of chlorobenzene and 50% aqueous NaOH solution based on our previous report [14]. When the reaction was run at 0–5 °C, an excellent yield (70%) and enantiomeric

• -methyl-7-methoxy-2-tetralone and a Mannich reaction to construct the tricyclic compound in eight linear steps. The optimization of reaction conditions were carried out to get a practical route delivering the product in excellent yield and purity (>99%). Experimental All solvents and reagents were from

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• %. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2-N-(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products

• compounds. The main objective of our current research was to elucidate the possibility of using carbocyclic diazodiketones in this photochemical process. For this purpose, diazocyclopentanediones 1a–g were tested in the study including unsubstituted diazocyclopentanedione 1a, tricyclic diazodiketones 1b–e

• ][39]. The structures of diazodiketones 1a–g were established using a standard set of spectroscopic methods (1Н and 13С NMR, IR and UV; for details, see Supporting Information File 1, Table S1) and in the case of the tricyclic diazodiketone 1с the structure was also confirmed by means of X-ray analysis

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• engage in π···π donor–acceptor attractions with the pyridinium moiety (outer most ring of the tricyclic moiety) and the two positively charged nitrogen atoms are per se much further apart due to the larger intramolecular separation between the intermolecularly interacting π-systems. In addition, the

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

• Lin-bo Luan Zi-jie Song Zhi-ming Li Quan-rui Wang Department of Chemistry, Fudan University, 2005 Songhu Road, Fudan University, Shanghai 200438, People’s Republic of China 10.3762/bjoc.14.155 Abstract Two new series of tricyclic heterocycles, namely 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d

• furnishing the tricyclic 1,2,4-triazole-fused 1,4-benzodiazepines. Keywords: 1,4-benzodiazepine (BDZ); cyclization; hydrazones; oxidation; rearrangement; Introduction Heterocyclic compounds comprising a 1,4-benzodiazepine (BDZ) ring have been a topic of continued interest as they exhibit a wide spectrum of

• , we wish to describe the synthesis of unprecedented tricyclic heterocycles, i.e., 5,6-dihydro-4H-benzo[b][1,2,4]triazolo[1,5-d][1,4]diazepinium salts 10 and the related neutral free base derivatives 13 via the cationic [3+ + 2]-cycloaddition/rearrangement reactions using the bicyclic 4-acetoxy-4-azo

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• ). Furthermore, spirolactam was used as intermediate in the synthesis of tricyclic compound 43 possessing a similar structure like that of the naturally occurring heterocyclic compound FR901483 [82]. Wardrop and co-workers [83] developed a new method for the preparation of 1-azaspiranes 47 by treatment of α- and

• ) in presence of 3.0 equivalents of TFA as an additive in dichloromethane (Scheme 17). The fused tricyclic compound 53 was obtained as major product in 55% yield along with the spiro compound 54 as a minor product in 8% yield. In 2009, Zhang and co-workers [89] reported an efficient method for the

• ). Furthermore, the absolute configuration of 88 was assigned by its single crystal X-ray analysis. 3.3. Application of spirolactams in natural product synthesis In 2001, Ciufolini and co-workers [103] employed PIDA (15) as an electrophile during the synthesis of naturally occurring tricyclic azaspirane

Metal-free formal synthesis of phenoxazine

• Gabriella Kervefors,
• Antonia Becker,
• Chandan Dey and
• Berit Olofsson

Beilstein J. Org. Chem. 2018, 14, 1491–1497, doi:10.3762/bjoc.14.126

• , unusually stable iodine(III) intermediate in the O-arylation was observed by NMR and could be converted to the product upon longer reaction time. Keywords: arylation; cyclization; diaryl ether; diaryliodonium salt; phenol; Introduction Phenoxazine (1) is a tricyclic compound consisting of an oxazine ring

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• spirocyclization of naphthol carboxylic acid [34]. Later Birman et al. reported a new variation of a chiral I(V) reagent, namely 2-(o-iodoxyphenyl)oxazoline derivative 28 [35]. The reagent was applied to an asymmetric [4 + 2] Diels–Alder dimerization of phenolic derivatives 29 to construct tricyclic derivatives 30

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• ]. Transformation of adduct 31 to 11 starts with the synthesis of the stable cyclopropanoid tricyclic 32 from the reaction of the 7-oxabenzonorbornadiene 31 with dichlorocarbene, generated by the phase-transfer method. The thermolysis of dichloride 32 in nitrobenzene at 165 °C resulted in the formation of ring

• anhydride (204) to give a tricyclic adduct 207 (in 90% yield) (Scheme 35) [141][142]. Later, Middlemiss’ group also used dienophiles such as maleic anhydride (204), N-methylmaleimide (205), and N-phenylmaleimide (206) to give endo-adducts 207–209 [148]. Furthermore, these ethenobenzocycloheptenones 207–209

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• bromocarbocyclization of aryl-geranyl derivatives using a combination of iodine(III) oxidant and a bromide source. In this fashion, the reaction of homogeranylbenzene with bis(tert-butylcarbonyloxy)iodobenzene and triethylsilyl bromide, followed by acidic treatment led to a tricyclic brominated adduct (Scheme 1

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

Continuous-flow retro-Diels–Alder reaction: an efficient method for the preparation of pyrimidinone derivatives

• Imane Nekkaa,
• Márta Palkó,
• István M. Mándity and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2018, 14, 318–324, doi:10.3762/bjoc.14.20

• the developed CF technology is superior to existing conventional batch technologies. Results and Discussion The starting materials, i.e., fused tricyclic or tetracyclic pyrimidinones 1–8 have been previously prepared by literature methods [26][45][46][47][48][49][50]. Cyclization of the corresponding

• di-exo- or di-endo-amino acids or esters with ethyl p-chlorobenzimidate resulted in tricyclic pyrimidinones 1, 2a and 2b [26][45][46][47][48][49]. Methanopyrrolo-, methanopyrido- and methanoazepino[2,1-b]quinazolinones 3–6 were prepared by ring enlargement of di-exo-norbornene-fused azetidinones with

• . The residence time was set by the use of coils with different lengths. The pressure and flow rate of the reactions were kept at constant values of 10 bars and 0.5 mL min−1, respectively. The full reaction parameter optimization is shown only for compound 1 in Table 1. The tricyclic di-exo-2-(4

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

• Lingjun Xu,
• Shuwen Han,
• Linjie Yan,
• Haifeng Wang,
• Haihui Peng and
• Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

• conveniently converted into the corresponding monoester products in high yields and enantioselectivities. Notably, bicyclic anhydrides (Table 2, entries 1 and 2) and tricyclic anhydrides (Table 2, entries 3 and 4) were more reactive than mono-cyclic anhydrides (Table 2, entries 5–12). In the case of mono

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• was accompanied by fluorescence quenching, and Vg-modified aegPNA has been used to probe the interaction between RNA quadruplexes and PNA [181]. Another example of a nucleobase with extended conjugation that has been incorporated into PNA is 1,3-diaza-2-oxophenothiazine (tC), which is a tricyclic

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

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• discovery of fluorinated liquid-crystalline (LC) molecules [10][11] led to the rational molecular design and synthesis of a family of novel fluorinated LC molecules that possess large negative dielectric anisotropy (Δε). In fact, as shown in Figure 1, tricyclic molecules containing a CF2CF2 carbocycle, e.g

• subsequently synthesized 1b, 1c, 2b, and 2c using the corresponding Grignard reagents, e.g., (4-n-PrC6H4)C6H4MgBr or 4-(trans-4-n-Pr-c-C6H10)C6H4MgBr, instead of 4-n-PrC6H4MgBr. As shown in Table 1, all reactions proceeded well to afford the corresponding adducts in acceptable to excellent yields. Tricyclic

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• . Keywords: B-to-Z-DNA transition; fluorescent base analogues; FRET; netropsin; nucleic acid structure and dynamics; quadracyclic adenines; tricyclic cytosines; Z-DNA; Review Introduction The importance of nucleic acid structure and dynamics in the understanding of vital processes in living organisms has

• probe BFdG, 3-MI, 2PyG, as well as the emissive RNA analogue thG [23][26][27][28]. Some notable pyrimidine analogues include our tricyclic analogues tC and tCO [29][30][31], pyrrolo-dC [32] and its derivatives [33] as well as thU, thC [23] and DMAC [34]. Apart from tC, tCO, qAN1 and thG, FBAs have not

• developing the family of fluorescent base analogues known as the tricyclic cytosines (tC) [14][29][30][31][35][36][37][38]. The aromatic core of tC was first prepared by Roth et al. in 1963 as part of a study to obtain pharmacologically active compounds structurally similar to phenothiazines [39]. Compound 1

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

• Irwan Iskandar Roslan,
• Kian-Hong Ng,
• Gaik-Khuan Chuah and
• Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

• regioselectively form this instead of 3a and 4. This tricyclic backbone can be found in compounds that possess a wide range of medicinal properties including those with antimalarial [74], anticancer [75][76], antiallergic [77][78], antibacterial [79], and antimicrobial properties [80][81]. In addition, they have

• attacks at both carbonyl groups to form benzo[4,5]thiazolo[3,2-a]pyrimidin-4-ones. The scope of these regiodivergent protocols was demonstrated with 19 examples of tricyclic benzo[d]imidazo[2,1-b]thiazoles and 27 examples of tricyclic and tetracyclic benzo[4,5]thiazolo[3,2-a]pyrimidin-4-ones. Experimental

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

• ]. The use of pyrocatechol or pyrogallol as reagents in reactions with the analogous mechanism resulted in the formation of mono-, di-, and tricyclic reaction products of phenol derivatives with one or two vinylphosphonium salt molecules (Scheme 62 and Scheme 63) [75]. In a similar reaction with 2

• nucleophilic displacement of the triphenylphosphonium group in intermediate α,β-di(alkoxycarbonyl)vinylphosphonium salts. Synthesis of 6-formylcoumarin derivatives and their application in the synthesis of dyads. Synthesis of di- and tricyclic coumarin derivatives in the reaction of pyrocatechol with two

• vinylphosphonium salt molecules. Synthesis of mono-, di-, and tricyclic derivatives in the reaction of pyrogallol with one or two vinylphosphonium salt molecules. Synthesis of 1,4-benzoxazine derivative by nucleophilic displacement of the triphenylphosphonium group in intermediate α,β-di(methoxycarbonyl

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• distance is 3.437(4) Å. Consequently, π–π interactions must be considered for this structure [51][52]. Bond lengths and angles of the reported crystal structures 4b, 5, and 6 are in the expected range. The tricyclic 1H-benzo[f]isoindole-1,3(2H)-dionyl moiety in 4b, 5 and the corresponding 3-imino-1-oxo-2,3

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• intermediate 45, which was subjected to Wittig olefination. Subsequent aza-Sakurai cyclization of intermediate 46 provided tricyclic derivative 47 as a single stereoisomer, which was then transformed into target myrioneurinol by standard operations. Addition of organometallic reagents to conjugated

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• ][30]. Alternative approaches by utilizing chiral backbones like, e.g., tartaric acid, biphenyls, or tricyclic ammonium salts were also heavily investigated [31][32][33][34][35], thus leading to an enormous recent progress in the field with respect to catalyst design and the development of new