Solution phase synthesis of short oligoribonucleotides on a precipitative tetrapodal support

• Alejandro Gimenez Molina,
• Amit M. Jabgunde,
• Pasi Virta and
• Harri Lönnberg

Beilstein J. Org. Chem. 2014, 10, 2279–2285, doi:10.3762/bjoc.10.237

• '-UUGCA-5', has been prepared on a precipitative tetrapodal tetrakis(4-azidomethylphenyl)pentaerythritol support. The 3'-terminal nucleoside was coupled to the support as a 3'-O-(4-pentynoyl) derivative by Cu(I) promoted 1,3-dipolar cycloaddition. Couplings were carried out with 1.5 equiv of the building

• reported [16] pentaerythritol-derived tetraazido support 7 was used to assemble a pentameric oligoribonucleotide, 5'-UUGCA-3', from the building blocks described above. The 3'-terminal block 6a was first attached to the support by Cu(I) promoted 1,3-dipolar cycloaddition [25][26] (Scheme 2). The procedure

End group functionalization of poly(ethylene glycol) with phenolphthalein: towards star-shaped polymers based on supramolecular interactions

• Carolin Fleischmann,
• Hendrik Wöhlk and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 2263–2269, doi:10.3762/bjoc.10.235

• and Discussion We herein describe the synthesis of the host and guest compound, which were further utilized for the preparation of star shaped polymers based on supramolecular interactions. The preparation of both, the host and the guest compound, occurred via 1,3-dipolar cycloaddition, in which the

N–O Cleavage reactions of heterobicycloalkene-fused 2-isoxazolines

• Jaipal R. Nagireddy,
• Geoffrey K. Tranmer,
• Emily Carlson and
• William Tam

Beilstein J. Org. Chem. 2014, 10, 2200–2205, doi:10.3762/bjoc.10.227

• these compounds (17, 18 and 19) was prepared in our laboratories by a combination of Diels–Alder cycloaddition and 1,3-dipolar cycloaddition reactions [21]. We found that the Raney nickel-mediated cleavage took place readily on 17 to yield a β-hydroxyketo-functionalized 7-oxanorbornane 20 (Scheme 3

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• polyoxin C hydrochloride 105*HCl (Scheme 44) [121]. The reaction cascade involved thermal formation of the corresponding azomethine ylide from substrate 105*HCl and benzaldehyde, followed by 1,3-dipolar cycloaddition of the ylide to N-methylmaleimide. The formation of compound 107 as the only product was

Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: new multivalent galectin-3 ligands

• Silvia Bernardi,
• Paola Fezzardi,
• Gabriele Rispoli,
• Stefania E. Sestito,
• Francesco Peri,
• Francesco Sansone and
• Alessandro Casnati

Beilstein J. Org. Chem. 2014, 10, 1672–1680, doi:10.3762/bjoc.10.175

• glycocalixarenes “Click Chemistry” [23] reactions are extensively used to conjugate (oligo)saccharides to macrocyclic structures due to the mild conditions and the high yields [24]. For the synthesis of glycocalixarenes the amino–isothiocyanate condensation [25][26][27][28][29][30] or the 1,3-dipolar cycloaddition

Triazol-substituted titanocenes by strain-driven 1,3-dipolar cycloadditions

• Andreas Gansäuer,
• Andreas Okkel,
• Lukas Schwach,
• Laura Wagner,
• Anja Selig and
• Aram Prokop

Beilstein J. Org. Chem. 2014, 10, 1630–1637, doi:10.3762/bjoc.10.169

• molecules. Since no metal complexes are required to catalyze the 1,3-dipolar cycloaddition [41][42][43], the reaction can be even used for the functionalization of biomolecules in living systems and has therefore been called bioorthogonal [34][35]. To the best of our knowledge, no examples of the Ti

• cycloaddition with an alkyne-functionalized titanocene has been described [44]. Therefore, the properties of triazol-substituted titanocenes, the products of the 1,3-dipolar cycloaddition, are also largely unexplored. Results and Discussion Synthesis of the titanocenes Preparation of the starting materials We

• functionalization through the strain-driven 1,3-dipolar cycloaddition with cyclooctyne. The original conditions of Wittig [36], the reaction of cyclooctyne with phenyl azide, and the numerous applications pioneered by Bertozzi suggest that the reaction proceeds under mild conditions [34][35][37][38][39][40

Synthesis and solvodynamic diameter measurements of closely related mannodendrimers for the study of multivalent carbohydrate–protein interactions

• Yoann M. Chabre,
• Alex Papadopoulos,
• Alexandre A. Arnold and
• René Roy

Beilstein J. Org. Chem. 2014, 10, 1524–1535, doi:10.3762/bjoc.10.157

• -azidoethyl α-D-mannopyranoside 3 [34] under classical copper-catalyzed dipolar cycloaddition (CuAAc) to afford 4 in 56% yield. Structure 4 was readily characterized by the absence of acetylenic protons at δ 3.16 ppm, the appearance of identical triazole protons (3H) at δ 7.74 ppm relative to the anomeric

Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• others, free radical polymerization of C-6 of the glucosamine residues with poly(ethylenglycol) acrylate [58]; free-radical polymerization of C-1 of glucosamine with mPEG [59] and 1,3-dipolar cycloaddition between the azide of an N-azidated chitosan and mPEG derivatives containing a triazolyl moiety [60

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

• Martin Popr,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142

• Huisgen 1,3-dipolar cycloaddition [30] (most popular ‘click reaction’) or the reduction to the amine. Our strategy involved the synthesis of the alkylation agent 1-azido-2-iodoethane (24) (Scheme 5) which would be used for the quaternization of the tertiary amine intermediate. The reaction sequence for

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• groups onto polymers via convenient ‘click’ reaction with organic azido molecules without PLA backbone degradation [17]. ‘Click’ chemistry [20], which is copper(I)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes, has been developed and utilized in recent years as a powerful synthetic strategy

Visible-light photoredox catalyzed synthesis of pyrroloisoquinolines via organocatalytic oxidation/[3 + 2] cycloaddition/oxidative aromatization reaction cascade with Rose Bengal

• Carlos Vila,
• Jonathan Lau and
• Magnus Rueping

Beilstein J. Org. Chem. 2014, 10, 1233–1238, doi:10.3762/bjoc.10.122

• type of compounds [22][23][24][25][26]. Recently, several metal mediated syntheses using a [3 + 2] cycloaddition reaction have been described in the literature. Porco Jr. et al. [27] described a silver-catalyzed cycloisomerization/dipolar cycloaddition for the synthesis of the pyrrolo[2,1-a

• . In this case, the addition of NBS was not necessary, and the corresponding products 6 were isolated in moderate yields (Scheme 3). Conclusion In conclusion, we have developed a metal-free photoredox oxidation/[3 + 2] dipolar cycloaddition/oxidative aromatization cascade catalyzed by Rose Bengal using

N-Alkylated dinitrones from isosorbide as cross-linkers for unsaturated bio-based polyesters

• Oliver Goerz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 902–909, doi:10.3762/bjoc.10.88

• unsaturated polyester was cross-linked by a 1,3-dipolar cycloaddition with the received dinitrones 10a/b. The 1,3-dipolar cycloaddition led to a strong change of the mechanical properties which were investigated by rheological measurements. Nitrones derived from methyl acrylate (3a) and methyl crotonate (3b

• ) were used as model systems and reacted with dimethyl itaconate to further characterize the 1,3-dipolaric cycloaddition. Keywords: bio-based polyesters; cross-linkers; dinitrones; 1,3-dipolar cycloaddition; isosorbide; Introduction Nitrones represent a class of compounds with a versatile use as

• -dipolar cycloaddition with unsaturated bio-based polyester poly(isosorbide itaconate -co- succinate). Results and Discussion N-Alkylated dinitrones derived from acrylates and crotonates were prepared and evaluated in respect to their 1,3-cycloaddition with itaconic acid containing polyester resins. To

Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism

• Denisa Tarabová,
• Stanislava Šoralová,
• Martin Breza,
• Marek Fronc,
• Wolfgang Holzer and
• Viktor Milata

Beilstein J. Org. Chem. 2014, 10, 752–760, doi:10.3762/bjoc.10.70

• ), 1,3-dipolar cycloaddition with diazo compounds as a source of N–N linkage, degradation of fused pyrazoles or rearrangement of other monocyclic heterocycles under chemical, thermal or photochemical conditions [4]. Upon reaction of hydrazine with symmetrical enol ethers, only a single product is formed

Copper–phenanthroline catalysts for regioselective synthesis of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and of pyrrolo[1,2-a]phenanthrolines under mild conditions

• Rupankar Paira,
• Tarique Anwar,
• Maitreyee Banerjee,
• Yogesh P. Bharitkar,
• Shyamal Mondal,
• Sandip Kundu,
• Abhijit Hazra,
• Prakas R. Maulik and
• Nirup B. Mondal

Beilstein J. Org. Chem. 2014, 10, 692–700, doi:10.3762/bjoc.10.62

• -700032, India 10.3762/bjoc.10.62 Abstract A new series of pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines and pyrrolo[1,2-a]phenanthrolines were efficiently built up from an 8-hydroxyquinoline derivative or phenanthroline via 1,3-dipolar cycloaddition reaction involving non-stabilized

• azomethine ylides, generated in situ from the parent furo[3,2-h]quinoliniums/phenanthroliums, in presence of a copper(II) chloride–phenanthroline catalytic system. The methodology combines general applicability with high yields. Keywords: copper(II) chloride–phenanthroline; 1,3-dipolar cycloaddition; furo

• [3,2-h]quinoliniums; phenanthroliums; pyrrolo[1,2-a]phenanthrolines; pyrrolo[3′,4′:3,4]pyrrolo[1,2-a]furoquinolines/phenanthrolines; Introduction The chemistry of the 1,3-dipolar cycloaddition has always been a fascinating undertaking especially when azomethine ylides are involved as the key component

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• -components that bear an additional alkene, alkyne or azide moiety and can be cyclized via either a deprotection–cyclization strategy, a ring-closing metathesis, a 1,3-dipolar cycloaddition or even via a sequence of multiple multicomponent reactions. The sequential IMCR-cyclization reactions can afford small

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• tautomerization. Instead, an Ag(I) complex based on BINAP and AgSbF6 was employed as a catalyst for the enantioselective 1,3-dipolar cycloaddition reaction of azomethine ylides and alkenes for the synthesis of pyrrolidines 81 and 82 (Scheme 38) [97]. The reaction was developed mainly as a two-component reaction

Additive-assisted regioselective 1,3-dipolar cycloaddition of azomethine ylides with benzylideneacetone

• Chuqin Peng,
• Jiwei Ren,
• Jun-An Xiao,
• Honggang Zhang,
• Hua Yang and
• Yiming Luo

Beilstein J. Org. Chem. 2014, 10, 352–360, doi:10.3762/bjoc.10.33

• 4-nitrobenzoic acid, respectively. The substituent effects on the regioselectivity were also investigated. Keywords: 1,3-dipolar cycloaddition; azomethine ylide; regioselectivity; spirooxindole; Introduction Spirooxindoles are important synthetic targets due to their significant biological

• with various dipolarophiles, such as α,β-unsaturated esters [21][22][23][24][25], dienones [26][27], α,β-unsaturated ketones [28][29][30], unsaturated aryl ketones [31][32][33] and electron-poor alkenes [34][35][36][37][38][39]. Among the studied α,β-unsaturated enones for 1,3-dipolar cycloaddition

• , chalcone derivatives are the most widely used dipolarophiles. Sarrafi and co-workers reported a 1,3-dipolar cycloaddition reaction of isatin, benzylamine and chalcone derivatives [31], and only one single regioisomer was obtained in high yield, in which the benzoyl group was connected to C-3 of the newly

Synthesis and biological activity of N-substituted-tetrahydro-γ-carbolines containing peptide residues

• Nadezhda V. Sokolova,
• Valentine G. Nenajdenko,
• Vladimir B. Sokolov,
• Daria V. Vinogradova,
• Elena F. Shevtsova,
• Ludmila G. Dubova and
• Sergey O. Bachurin

Beilstein J. Org. Chem. 2014, 10, 155–162, doi:10.3762/bjoc.10.13

• described the conjugation of N-substituted tetrahydro-γ-carbolines containing a terminal alkyne group 3a–d with various azidopeptides 5 (prepared by Ugi multicomponent reaction) through the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition. The activity of the obtained compounds on rat liver mitochondria

The regioselective synthesis of spirooxindolo pyrrolidines and pyrrolizidines via three-component reactions of acrylamides and aroylacrylic acids with isatins and α-amino acids

• Tatyana L. Pavlovskaya,
• Fedor G. Yaremenko,
• Victoria V. Lipson,
• Svetlana V. Shishkina,
• Oleg V. Shishkin,
• Vladimir I. Musatov and
• Alexander S. Karpenko

Beilstein J. Org. Chem. 2014, 10, 117–126, doi:10.3762/bjoc.10.8

• aroylacrylic acids as dipolarophiles has been realized through a one-pot 1,3-dipolar cycloaddition protocol. Decarboxylation of 2'-aroyl-2-oxo-1,1',2,2',5',6',7',7a'-octahydrospiro[indole-3,3'-pyrrolizine]-1'-carboxylic acids is accompanied by cyclative rearrangement with formation of dihydropyrrolizinyl

• inhibitors [9][10]. The multicomponent 1,3-dipolar cycloaddition of azomethine ylides, generated in situ via decarboxylative condensation of isatins and α-amino acids with olefinic and acetylenic dipolarophiles, represents a key approach for the regio- and stereoselective construction of a variety of complex

• inhibitors there are compounds containing a pyrrolidine-2-one as a part of the spirocyclic system [34]. In the present work we report the synthesis of spirooxindolo pyrrolidines and pyrrolizidines by utilizing a 1,3-dipolar cycloaddition of hitherto uninvestigated acrylamides and aroylacrylic acids with

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

• involves several steps: the 1,3-dipolar cycloaddition of ozone to the double bond to form unstable 1,2,3-trioxolane 164 (so-called molozonide) that is followed by its decomposition to a peroxycarbenium ion and a carbonyl compound (Criegee intermediates). The 1,3-dipolar cycloaddition of the intermediates

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

• formation of these compounds can be rationalized by pathways presented in Scheme 2 [4][22]. 1) Pathway A implies the initial 1,3-dipolar cycloaddition between the diazo compound 2 and the С=S bond of thioketone 1 giving rise to 1,3,4-thiadiazoline 10. The latter is usually an unstable intermediate species

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• but-2-ynedioate and phenyl azide at 100 °C in a sealed tube and suggested that regioisomeric triazoles were formed [1]. However, it was only in the 1960s that Huisgen recognized this type of reaction for its generality, scope and mechanism [2][3][4][5], and coined the term 1,3-dipolar cycloaddition

• a factor of up to 107 in comparison to Huisgen’s uncatalyzed procedure [13][14]. Since Meldal and Sharpless had first reported this copper-catalyzed variant of Huisgen’s 1,3-dipolar cycloaddition, a myriad of protocols employing different catalyst systems has been described. It is essential for the

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

• , Universidad del País Vasco, Apdo. 1072, E-20018 San Sebastián, Spain IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain 10.3762/bjoc.9.280 Abstract The 1,3-dipolar cycloaddition between glycine-derived azlactones with maleimides is efficiently catalyzed by the dimeric chiral complex [(Sa

• : asymmetric catalysis; DFT; 1,3-dipolar cycloaddition; gold catalysis; NICS; NTR; oxazolones; prolines; Introduction The synthesis of α-amino acids employing an α-amino carbonyl template constitutes the most straightforward route to introduce the α-side chain [1]. As a valid example, oxazol-5-(4H)-ones

• electrophilic alkenes have not been exploited. Toste´s group published an efficient 1,3-dipolar cycloaddition (1,3-DC) between alanine, phenylalanine and allylglycine derived azlactones with maleimides and acrylates employing dimetallic (S)-Cy-Segphos(AuOBz)2 complex 1 as a catalyst (2 mol %) in the absence of

Synthesis of enantiopure sugar-decorated six-armed triptycene derivatives

• Paola Bonaccorsi,
• Maria Luisa Di Gioia,
• Antonella Leggio,
• Lucio Minuti,
• Teresa Papalia,
• Carlo Siciliano,
• Andrea Temperini and
• Anna Barattucci

Beilstein J. Org. Chem. 2013, 9, 2410–2416, doi:10.3762/bjoc.9.278

• is the first example of six-armed carbohydrate-substituted triptycenes, which appear as promising candidates for the development of new supramolecular systems with specific properties. Results and Discussion The Huisgen 1,3-dipolar cycloaddition reaction, which represents the key step of click

A one-pot synthesis of 3-trifluoromethyl-2-isoxazolines from trifluoromethyl aldoxime

• Raoni S. B. Gonçalves,
• Michael Dos Santos,
• Guillaume Bernadat,
• Danièle Bonnet-Delpon and
• Benoit Crousse

Beilstein J. Org. Chem. 2013, 9, 2387–2394, doi:10.3762/bjoc.9.275

• reacted with olefins (such as styrene, allyl derivatives, etc.) through a 1,3-dipolar cycloaddition to give the desired product. Therefore, the development of a straightforward and mild general procedure to access these valuable derivatives remains of great importance. In the present work, we describe a

• unreactive towards trifluoroacetonitrile oxide 4. 1,3-Dipolar cycloaddition reactions have been studied from the theoretical standpoint since the 1970’s onwards [36][37] with an ever-increasing accuracy as computational methods evolved [38]. Assuming that the above-mentioned transformations occur via a