Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• the 13C NMR spectra (102.3–105.3 ppm; Table 3) similarly to the compounds 9a,c described in literature [7]. The tricyclic analogue 3g obtained from diazodimedone (2g) and thioketone 1a showed the absorption signal of the C(2)-atom at lower field (106.8 ppm) most likely due to the stronger deshielding

• contrast, tricyclic derivative 3g displays a chemical shift of C(5) at a lower field (166.6 ppm), most likely due to the similar reasons as for deshielding effect observed for the atom C(2). However, in the case of С(5) this effect is considerably stronger, since this atom is a vinylogue of the C=O group

Synthesis of indole-based propellane derivatives via Weiss–Cook condensation, Fischer indole cyclization, and ring-closing metathesis as key steps

• Sambasivarao Kotha,
• Ajay Kumar Chinnam and
• Arti Tiwari

Beilstein J. Org. Chem. 2013, 9, 2709–2714, doi:10.3762/bjoc.9.307

• propellane derivatives involves a Weiss–Cook condensation, a Fischer indole cyclization, and a ring-closing metathesis as key steps. Keywords: allylation; indole derivatives; propellanes; ring-closing metathesis; Weiss–Cook condensation; Introduction Propellanes are tricyclic systems conjoined with carbon

IBD-mediated oxidative cyclization of pyrimidinylhydrazones and concurrent Dimroth rearrangement: Synthesis of [1,2,4]triazolo[1,5-c]pyrimidine derivatives

• Caifei Tang,
• Zhiming Li and
• Quanrui Wang

Beilstein J. Org. Chem. 2013, 9, 2629–2634, doi:10.3762/bjoc.9.298

• pyrimidine moiety is an important pharmacophore [1]. Especially, the fused bi- or tricyclic heterocyles containing a pyrimidine motif have received considerable interest in the design and discovery of new compounds for pharmaceutical and herbicidal applications [2][3]. For example, the pyrrolo[2,3-d

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• hydroamination intermediate affording tricyclic 3-benzazepines 129 (Scheme 32c). In the same field, Zhang reported the carboamination, carboalkoxylation and carbolactonization of terminal alkenes with arylboronic acids. Under best conditions, oxidative gold catalysis provided expedient access to various

• on the efficiency of gold catalysis in the functionalization of C–H bonds [77]. In particular, N-aryl-N’-allylureas 136 were selectively transformed into tricyclic indolines 137 in good yields. The reaction preceeded through the regioselective 5-exo anti-aminoauration of the C–C double bond (139

• carbolactonization of terminal alkenes with arylboronic acids. Synthesis of tricyclic indolines via gold-catalyzed formal [3 + 2] cycloaddition. Gold(I) catalyzed aminoarylation of terminal alkenes in presence of Selectfluor [dppm = bis(diphenylphosphino)methane]. Mechanistic investigation on the aminoarylation of

Synthetic scope and DFT analysis of the chiral binap–gold(I) complex-catalyzed 1,3-dipolar cycloaddition of azlactones with alkenes

• María Martín-Rodríguez,
• Luis M. Castelló,
• Carmen Nájera,
• José M. Sansano,
• Olatz Larrañaga,
• Abel de Cózar and
• Fernando P. Cossío

Beilstein J. Org. Chem. 2013, 9, 2422–2433, doi:10.3762/bjoc.9.280

• agreement with the experimental results (Table 2, entry 1). The complete reaction path of the cycloaddition process is shown in Scheme 4. We do not study computationaly the second synthetic step, namely the ring-opening of the tricyclic-cycloadduct, because that step has no relevance in the stereochemical

Direct electrophilic N-trifluoromethylthiolation of amines with trifluoromethanesulfenamide

• Sébastien Alazet,
• Kevin Ollivier and
• Thierry Billard

Beilstein J. Org. Chem. 2013, 9, 2354–2357, doi:10.3762/bjoc.9.270

• bis-amines can also be trifluoromethylthiolated, with the most nucleophile atom as a target (Figure 2). In this case, 2.1 equiv of BuLi are required and reaction times are loner (20 h). This new method was applied to synthesize a trifluoromethylthio analog (3l) of the well-known tricyclic

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• of platelet activating factor (PAF) and of histamine used in the treatment of allergies. This compound consists of a highly functional tricyclic core with an unsaturated linkage to a pendant piperidine ring. The picoline derivative 1.23 is first treated with two equivalents of n-butyllithium (n-BuLi

• substituted Grignard reagent 1.26. A Friedel–Crafts type acylation promoted by either triflic acid or polyphosphoric acid (PPA) furnishes the tricyclic structure 1.28 which upon N-demethylation affords clarinex (1.22). One of the top-selling classes of pharmaceuticals containing the pyridine ring are the

• (D)-(+)-O,O-dibenzoyltartaric acid was reported to separate the enantiomers [61]. By analogy to moxifloxacin the synthesis of levofloxacin (1.103) can be accomplished using an intramolecular double SNAr reaction sequence converting the tetrafluoroarene 1.116 into the required tricyclic

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• % yield when heated at 150 °C, presumably through strained tricyclic transition state 27a [1]. In contrast, nitronic ester 26b fails to undergo rearrangement presumably owing to the requirement that the nitro and phenyl groups be cis in the product. The rearrangement of nitronic ester 7 to give nitro

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• provided the depicted endo-diastereomer in good yield. Exchange of the N-benzyl for a Boc-protecting group and cleavage of the silyl enol ether gave the corresponding ketone, which was first converted to an enol-triflate and then to the tricyclic alkene 73. At this stage, the syntheses of cytochalasin B

Cyclization of substitued 2-(2-fluorophenylazo)azines to azino[1,2-c]benzo[d][1,2,4]triazinium derivatives

• Aleksandra Jankowiak,
• Emilia Obijalska and
• Piotr Kaszynski

Beilstein J. Org. Chem. 2013, 9, 1873–1880, doi:10.3762/bjoc.9.219

• computational results. Keywords: DFT; heterocycles; mechanism; synthesis; Introduction Derivatives of benzo[c]quinolizinium [1][2][3][4] (I, X = Y = CH, Figure 1) and its di-aza analogue pyrido[2,1-c]benzo[d][1,2,4]triazinium (I, X = Y = N) belong to a class of tricyclic cations featuring general structure I

• substituents at the benzene ring were prepared by acid-catalyzed photoinduced cyclization of phenylazopyridines [5]. Recently, we demonstrated an efficient alternative method for the formation of 1a and other parent tricyclic azinium cations of general structure I (A = B = H) by light-induced intramolecular

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• substrate for desymmetrization with other reported organocatalysts, and the chlorohydrin 94 was obtained in 90% ee in the presence of 10 mol % of OC-98 in dichloromethane at −90 °C. Interestingly, the tricyclic exo-norbornene oxide afforded the syn-exo-chloroalcohol 123 as the major product in 53% yield and

A reductive coupling strategy towards ripostatin A

• Kristin D. Schleicher and
• Timothy F. Jamison

Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175

• titanium-mediated, alkoxide-directed fragment coupling reaction between vinylcylopropanes and vinyldimethylchlorosilane (Scheme 3, reaction 4) in which the stereochemical outcome of the rearrangement is orchestrated by the adjacent alkoxide, which is believed to direct formation of a tricyclic

Mechanistic studies on the CAN-mediated intramolecular cyclization of δ-aryl-β-dicarbonyl compounds

• Brian M. Casey,
• Dhandapani V. Sadasivam and
• Robert A. Flowers II

Beilstein J. Org. Chem. 2013, 9, 1472–1479, doi:10.3762/bjoc.9.167

• rings (Table 2, entries 5 and 6) did not occur, and oxidation of 1h and 1i instead favored the formation of methyl esters 2h and 2i. Finally, the tricyclic product 2j was generated in an isolated yield of 61% when substrate 1j was oxidized. It is important to note that products 2g and 2j were isolated

Dipolar addition to cyclic vinyl sulfones leading to dual conformation tricycles

• Steven S. Y. Wong,
• Michael G. Brant,
• Christopher Barr,
• Allen G. Oliver and
• Jeremy E. Wulff

Beilstein J. Org. Chem. 2013, 9, 1419–1425, doi:10.3762/bjoc.9.159

• the origin of the fluxional behavior was probed by NMR methods together with DFT calculations. This behavior was ultimately attributed to stereochemical inversion at one of two nitrogen centers embedded in the tricyclic framework. Two tetracycles were also synthesized, and the degree of signal

• pathways are open to the reactants. The additional aromatic substituent in 7 (relative to 4) once again contributed to significant broadening in both the 1H and 13C NMR spectra. Conclusion Our results comprise the first syntheses of tricyclic sulfones by 1,3-dipolar cycloadditions of azomethine imines with

Exploration of an epoxidation–ring-opening strategy for the synthesis of lyconadin A and discovery of an unexpected Payne rearrangement

• Brad M. Loertscher,
• Yu Zhang and
• Steven L. Castle

Beilstein J. Org. Chem. 2013, 9, 1179–1184, doi:10.3762/bjoc.9.132

• triggered by exposure of trimesylate 2 or a related electrophile to ammonia. A sequential alkylation process would serve as a viable alternative in the event of problems with this approach. In turn, cis-fused trimesylate 2 could be derived from trans-fused tricyclic ketone 3 by epimerization and standard

Synthesis and physicochemical characterization of novel phenotypic probes targeting the nuclear factor-kappa B signaling pathway

• Paul M. Hershberger,
• Satyamaheshwar Peddibhotla,
• E. Hampton Sessions,
• Daniela B. Divlianska,
• Ricardo G. Correa,
• Anthony B. Pinkerton,
• John C. Reed and
• Gregory P. Roth

Beilstein J. Org. Chem. 2013, 9, 900–907, doi:10.3762/bjoc.9.103

• tricyclic condensation side product 5 was completely eliminated by performing the reaction with sodium bicarbonate at 23 °C in methanol (Scheme 1, Method B). Thus, compound 4 was isolated as a lyophilized white powder in 78% yield and >98% purity. Deeper in vitro biological investigation using 4 as a

Intramolecular carbonickelation of alkenes

• Rudy Lhermet,
• Muriel Durandetti and
• Jacques Maddaluno

Beilstein J. Org. Chem. 2013, 9, 710–716, doi:10.3762/bjoc.9.81

• construct tricyclic skeletons with an all-carbon quaternary center at a ring junction. This pattern is found in important natural products such as morphine whose ACE ring system exhibits a tetrahydrodibenzofuran motif with an angular ethylamino chain on C13. We thought that the nickel-catalyzed

• the expected (and sole) tricyclic product 14 in 52% isolated yield, resulting from a nickel-catalyzed intramolecular base-free Heck-type coupling and exhibiting an all-carbon quaternary center at a cis-ring junction (as established by NOESY experiments). This result, added to that obtained above with

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• represents a model study for the total synthesis of gilvocarcin M (47), a natural C-glycoside [27]; while the latter illustrates the possibility of constructing a cyclobutane-containing tricyclic motif related to the one found in penitrem D, 50 [28]. The two-step formation of tetralone 53, starting from

• adduct 62 to the action of potassium carbonate, in a mixture of acetonitrile and tert-butanol under reflux, leads to tricyclic thiochromanone 63 in high yield [32]. This transformation involves attack of the ketone enolate on the thiocarbonyl group of the nearby xanthate, followed by substitution of the

• sulfone is necessary: when the Mannich reaction of benzothiepinone 65b with formaldehyde was attempted, the reaction resulted in the formation of novel tricyclic sulfonium 69 in modest yield [32]. It is also possible to profit from the ability of xanthates to mediate additions to olefins containing

A one-pot catalyst-free synthesis of functionalized pyrrolo[1,2-a]quinoxaline derivatives from benzene-1,2-diamine, acetylenedicarboxylates and ethyl bromopyruvate

• Mohammad Piltan,
• Loghman Moradi,
• Golaleh Abasi and
• Seyed Amir Zarei

Beilstein J. Org. Chem. 2013, 9, 510–515, doi:10.3762/bjoc.9.55

• derivative, the pyrrolo[1,2-a]quinoxaline moiety, in particular, is a tricyclic compound having biological activity [14][15][16][17][18][19]. The syntheses of pyrrolo[1,2-a]quinoxaline derivatives have hitherto been reported by only a few researchers, and they normally required additional additives and long

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• iterative arylzincation/allenylation reactions (Scheme 50). Zirconium-catalyzed dimerization of 1,2-dienes in preparation for the synthesis of useful 1,4-diorganomagnesium compounds from 1,2-dienes (Scheme 51) and its application to the synthesis of tricyclic compounds (Scheme 52) was reported [137][138

• coupling reaction of 1,2-allenoate, organozinc reagent, and ketone. Proposed mechanism for a rhodium-catalyzed arylzincation of allenes. Synthesis of skipped polyenes by iterative arylzincation/allenylation reaction. Synthesis of 1,4-diorganomagnesium compound from 1,2-dienes. Synthesis of tricyclic

One-pot tandem cyclization of enantiopure asymmetric cis-2,5-disubstituted pyrrolidines: Facile access to chiral 10-heteroazatriquinanes

• Ping-An Wang,
• Sheng-Yong Zhang and
• Henri B. Kagan

Beilstein J. Org. Chem. 2013, 9, 265–269, doi:10.3762/bjoc.9.32

• established that the reduction product 5a (Figure 3) was formed with a rigid 10-heteroazaquinane skeleton through an intramolecular Lewis acid–base pair interaction [15][16][17][18]. Three five-membered rings are fused to give a very stable bowl-shaped tricyclic system with five stereogenic centers

Dipyrazolo[1,5-a:4',3'-c]pyridines – a new heterocyclic system accessed via multicomponent reaction

• Wolfgang Holzer,
• Gytė Vilkauskaitė,
• Eglė Arbačiauskienė and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2012, 8, 2223–2229, doi:10.3762/bjoc.8.251

• multicomponent reaction affording new tricyclic compounds with a dipyrazolo[1,5-a:4',3'-c]pyridine core. Detailed NMR spectroscopic investigations (1H, 13C and 15N) were undertaken with all obtained compounds. Keywords: cyclization; nitrogen heterocycles; NMR spectroscopy; multicomponent reaction; pyrazole

• butyraldehyde by propionaldehyde (4b) or 3-phenylpropanal (4c) afforded the corresponding tricyclic products 5g, 5h and 5i in 59–73% yield, respectively (Table 1, entries 7–9). Lastly, application of the cyclic ketones cyclopentanone (4d), cyclohexanone (4e) and 2-methylcyclohexanone (4f) as carbonyl components

Features of the behavior of 4-amino-5-carboxamido-1,2,3-triazole in multicomponent heterocyclizations with carbonyl compounds

• Eugene S. Gladkov,
• Katerina A. Gura,
• Svetlana M. Sirko,
• Sergey M. Desenko,
• Ulrich Groth and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2012, 8, 2100–2105, doi:10.3762/bjoc.8.236

• (Method D) was the procedure of choice in this case as well. Multicomponent heterocyclizations of aminotriazole 1 with aromatic aldehydes 6a–e and cyclohexanediones 8a,b carried out according to Method A, B or C yielded tricyclic compounds 9a–j in 51–91% (Scheme 2, Table 1). The most efficient synthetic

Tricyclic flavonoids with 1,3-dithiolium substructure

• Lucian G. Bahrin,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2012, 8, 1999–2003, doi:10.3762/bjoc.8.226

• a mixture of diastereoisomers, the anti isomer being the major one. The heterocyclization of these compounds provided novel tricyclic flavonoids bearing a 1,3-dithiolium-2-yl ring fused at the 3,4-carbon positions of the benzopyran moiety. Keywords: aminals; benzopyrans; dithiocarbamates

• synthesized from a tricyclic flavonoid bearing a 1,3-dithiolium-2-yl unit as C ring [15]. These complexes have been electrochemically investigated to provide a better understanding of enzymatic activities in thermophilic and hyperthermophilic organisms. This paper outlines the synthesis of novel tricyclic

• heterocyclization of compounds 6 should, hence, provide new tricyclic fused flavonoids 7 by using an appropriate mixture of acids, as described above (Scheme 1, Table 1). Using a concentrated sulfuric acid/glacial acetic acid (1:3 v/v) mixture [22][23][24] the cyclization of dithiocarbamates 6a–f takes place under