Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• . E. Simanek and co-workers [1] and then by K. Takagi and co-workers [2] as part of an innovative development of convergent [1][3][4] and divergent [1][5][6] strategies towards iterative dendritic synthesis. Along with their expansion, both the biological impact of the above arborescent structures

• )phenylamino]-s-triazine B, a known starting material for plastics manufacturing [40] and divergent G-1 dendritic synthesis [41], was obtained using 4-aminophenol as amine nucleophile and reacting it with cyanuric chloride by applying a previously patented protocol [40] completed with our own subsequent

• improvements [36]. With regard to (4-aminophenoxy)alkanoic acid-based tripodal melamines C1 and C3, we recently reported their synthesis in three steps via convergent (starting from N-acetyl-4-aminophenol, also known as paracetamol) and divergent (via A) strategies [42] which are summarised in Scheme 1. All

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• availability of homogeneous structurally distinct lipid A, the development of divergent and reproducible approaches for the synthesis of various types of lipid A has become a subject of considerable importance. This review focuses on recent advances in synthetic methodologies toward LPS substructures

• lipid A substructures were synthesized. This review summarizes synthetic approaches developed in the past decade toward diverse LPS partial structures from different bacterial species including lipid A. The review provides comprehensive insight into the divergent and complex chemistry hidden under

How and why kinetics, thermodynamics, and chemistry induce the logic of biological evolution

• Addy Pross and
• Robert Pascal

Beilstein J. Org. Chem. 2017, 13, 665–674, doi:10.3762/bjoc.13.66

• divergent nature [47]. Indeed, provided that the environment provides energy in sufficient quantities and potential to sustain life, there should be no end to the evolutionary process as neither DKS, nor the complexity which accompanies it, appear to have an upper bound. A free energy potential threshold as

Exploring endoperoxides as a new entry for the synthesis of branched azasugars

• Svenja Domeyer,
• Mark Bjerregaard,
• Henrik Johansson and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2017, 13, 644–647, doi:10.3762/bjoc.13.63

• that endoperoxides might provide a new entry to branched azasugars with novel stereochemistry and substitution patterns (Scheme 1). Herein we wish to report our preliminary results in synthesising nitrogen containing endoperoxides as a potential new source for the divergent synthesis of azasugars

• marketed drugs Glyset and Zavesca. Bottom: Our synthetic strategy aimed to explore substituted endoperoxides (e.g. dihydroxylated endoperoxide, box) as key intermediates for the divergent synthesis of novel azasugars. PG = protection group. Synthesis of Boc- and Pht-protected diene substrates for

Polyketide stereocontrol: a study in chemical biology

• Kira J. Weissman

Beilstein J. Org. Chem. 2017, 13, 348–371, doi:10.3762/bjoc.13.39

• with the conserved Leu. In the alternative proposal [62], the direction of reduction is controlled by a divergent degree of ordering within the active sites of A- and B-type domains. In A-type KRs, cofactor binding generates a well-organized and catalysis-ready active site, in which a key residue (Met

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• tolerate many sensitive functional groups, such as free alcohols, silyl enol ethers, and ketones, which makes it an attractive metal for late stage functionalization and elaboration of complex molecules. It is thought that the origin of ruthenium’s divergent behavior stems from a difference in reaction

• relative to substrate. Diastereomeric metal complexes formed after alcohol coordination. Divergent behavior of the palladium and ruthenium-catalyzed Alder–ene reaction. Some asymmetric enyne cycloisomerization reactions. Synthesis of p-anisyl catalyst 1. Using norephedrine-based oxathiazolidine-2-oxide 7

Modular synthesis of the pyrimidine core of the manzacidins by divergent Tsuji–Trost coupling

• Sebastian Bretzke,
• Stephan Scheeff,
• Felicitas Vollmeyer,
• Friederike Eberhagen,
• Frank Rominger and
• Dirk Menche

Beilstein J. Org. Chem. 2016, 12, 1111–1121, doi:10.3762/bjoc.12.107

• ][31]. Conclusion In summary, we have reported in full details the design, development and application of an efficient method for the synthesis of the tetrahydropyrimidinone core of the manzacidins by a divergent intramolecular allylic substitution reaction. The application of this approach enabled a

• precursor 5. Divergent Tsuji–Trost coupling and completion of the synthesis of authentic pyrimidinones 3 and 4. Supporting Information Supporting Information File 132: Full experimental details, characterization data of all products, copies of 1H and 13C NMR spectra and X-ray crystallographic data for 28

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• in Cheng’s group revealed an intriguing divergent catalytic dimerisation of 2-formylcinnamates 72. Co-operative catalysis by NHC precatalyst 73 and a Lewis acid (titanium isopropoxide) afforded isochromenone derivatives 74 via a sequence of reactions initiated by a benzoin condensation. Treatment of

• –Michael cascade. Divergent catalytic dimerization of 2-formylcinnamates. One-pot, multicatalytic asymmetric synthesis of tetrahydrocarbazole derivatives. NHC-chiral secondary amine co-catalysis for the synthesis of complex spirocyclic scaffolds.

Synthesis of bi- and bis-1,2,3-triazoles by copper-catalyzed Huisgen cycloaddition: A family of valuable products by click chemistry

• Zhan-Jiang Zheng,
• Ding Wang,
• Zheng Xu and
• Li-Wen Xu

Beilstein J. Org. Chem. 2015, 11, 2557–2576, doi:10.3762/bjoc.11.276

• 5,5’-bitriazoles from acetylenic amide. The amine-functionalized polysiloxane-mediated divergent synthesis of trizaoles and bitriazoles. The cyclic BINOL-based 5,5’-bitriazoles. The one-pot click–click reactions for the synthesis of bistriazoles. The synthesis of bis(indolyl)methane-derivatized 1,2,3

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• 10.3762/bjoc.11.175 Abstract The construction of redox-active supramolecular assemblies based on star-shaped and radially expanded tetrathiafulvalene (TTF) oligomers with divergent and extended conjugation is summarized. Star-shaped TTF oligomers easily self-aggregate with a nanophase separation to

• derivatives, radially expanded or star-shaped multi-TTFs with C3 and C6 symmetries have attracted considerable attention in the field of materials science because of their divergent and extended π-conjugation. Various C3-symmetric compounds incorporating three conjugated TTF units were designed and

Thiazole-induced rigidification in substituted dithieno-tetrathiafulvalene: the effect of planarisation on charge transport properties

• Rupert G. D. Taylor,
• Joseph Cameron,
• Iain A. Wright,
• Neil Thomson,
• Olena Avramchenko,
• Alexander L. Kanibolotsky,
• Anto R. Inigo,
• Tell Tuttle and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1148–1154, doi:10.3762/bjoc.11.129

• constructing a half-unit functionalised with a 1,3-dithiol-2-one, that can undergo a triethyl phosphite-mediated homocoupling to synthesise the central dithienoTTF in the final step. Herein, we present an alternative divergent route to dithienoTTFs, by utilising 4,6,4’,6’-tetrabromo-[2,2’]bis(thieno[3,4-d][1,3

• ]dithiolylidene) [15] as a core and appending heterocyclic arms through microwave assisted Stille couplings. It is worth noting that the tetrabromo-dithienoTTF core is still prepared via a triethyl phosphite-mediated homocoupling, but in this divergent route valuable heterocyclic groups can be introduced at the

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• tedious and multistep syntheses using either divergent or convergent approaches are arguably the reason for their limited use as support in organic synthesis [18]. To overcome these obstacles, a hybrid dendron-polymer might constitute a valuable alternative for high-loading platforms [19], despite the use

A modular phosphate tether-mediated divergent strategy to complex polyols

• Paul R. Hanson,
• Susanthi Jayasinghe,
• Soma Maitra,
• Cornelius N. Ndi and
• Rambabu Chegondi

Beilstein J. Org. Chem. 2014, 10, 2332–2337, doi:10.3762/bjoc.10.242

• Paul R. Hanson Susanthi Jayasinghe Soma Maitra Cornelius N. Ndi Rambabu Chegondi Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045-7582, USA 10.3762/bjoc.10.242 Abstract An efficient and divergent synthesis of polyol subunits utilizing a phosphate tether

• component in several potent biologically active polyketides [1][2][3][4]. This prevalence has led to the development of various synthetic methods for their construction [5]. In particular, divergent strategies are ideal for analog generation [6][7][8][9][10][11], which in turn, can enhance the quality of

• screening decks in early phase drug discovery. One aim of divergent synthetic strategies is to produce multiple scaffolds from a single set of starting materials [12]. In this regard, one-pot, sequential processes [13][14][15][16] are well suited to address this challenge by forming multiple bonds and

Convergent synthetic methodology for the construction of self-adjuvanting lipopeptide vaccines using a novel carbohydrate scaffold

• Vincent Fagan,
• Istvan Toth and
• Pavla Simerska

Beilstein J. Org. Chem. 2014, 10, 1741–1748, doi:10.3762/bjoc.10.181

• previously reported carbohydrate-based vaccine constructs [11] were prepared by a divergent approach, where the carbohydrate core was coupled to the resin-bound LCP adjuvanting moiety, followed by stepwise synthesis of the B cell epitopes using solid-phase peptide synthesis (SPPS). Using this divergent

• , where each building block can be synthesized and purified prior to final assembly of the vaccine candidates. The building blocks may be assembled in different ways so that libraries of vaccine candidates can be prepared faster and more efficiently compared to the previous divergent approach. Results and

• ‘click’ reaction [20] was employed to couple multiple copies of purified B cell peptide antigens onto the carbohydrate core and lipidic adjuvanting moiety. This type of convergent approach has a number of advantages over the previously described divergent route. Since each component is synthesized

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

• shown). Synthesis of mannosylated trimers 5 and 9 using trimesic acid core transformed into propargylated (2) and azidopropylated (6) scaffolds and then coupled by “click chemistry” with either 2-azidoethyl (3) or propargyl (7) mannopyranosides. Divergent CuAAc “click reaction” between propargylated

• core 10 and azide 3 to afford 9-mer 12. Divergent CuAAc synthesis of “extended” 9-mer 17 using phloroglucinol (13) as core, bromoacylated TRIS as linker and mannopyranosylazide 3. Convergent synthesis of further “extended” 9-mer 21 using mannosylated bromoacyl dendron 18 transformed into azide 19

Design and synthesis of multivalent neoglycoconjugates by click conjugations

• Feiqing Ding,
• Li Ji,
• Ronny William,
• Hua Chai and
• Xue-Wei Liu

Beilstein J. Org. Chem. 2014, 10, 1325–1332, doi:10.3762/bjoc.10.134

• especially versatile for the effective construction of complex glycosylated structures such as clusters, dendrimers, polymers, peptides and macrocycles. In all the cases the triazole ring plays a crucial role in combining divergent units together to establish a complex molecular architecture [23][24][25][26

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• then debenzylated under standard hydrogenation conditions with concomitant reduction of the double bond, thus leading to lipidated amino acid building block 41 suitable for SPPS in 75% yield for the final step. Conclusion In summary, we have developed a divergent approach for the synthesis of several

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• synthesized chemically and isolated, it has to be taken into account that they often tend to undergo destructive side reactions. Therefore, mild reaction conditions are required, and the synthetic routes to them should preferably be organized in a divergent fashion that allows flexible access to all target

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• 5 were obtained in pure form in 78–94% yields (Scheme 2 and Table 2). It is noteworthy, that a similar reaction, in which the less hindered, more reactive formaldehyde was employed as the aldehyde component, took a completely divergent course and afforded 5-arylcarbonyl-1,3

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

• Christina Lohoelter,
• Malte Brutschy,
• Daniel Lubczyk and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2013, 9, 2821–2833, doi:10.3762/bjoc.9.317

• divergent–concave arrangement of functionalities can be obtained upon installation of building blocks with a linear geometry (Figure 3, right). Here, the functionalization of (−)-isosteviol-based triphenylene ketal all-syn-2a as well as the combination of (−)-isosteviol with the triptycene platform is

Gold(I)-catalyzed domino cyclization for the synthesis of polyaromatic heterocycles

• Mathieu Morin,
• Patrick Levesque and
• Louis Barriault

Beilstein J. Org. Chem. 2013, 9, 2625–2628, doi:10.3762/bjoc.9.297

• divergent pathway can be obtained by modulating the steric and electronic properties of the gold(I) catalyst (Scheme 1). The ancillary ligand plays a direct role in the regioselectivity for the first bond formation rather than via a common intermediate created after an initial bond formation [18]. Indeed

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• , including nitroalkanes, was shown to add to iminium ions. The authors proposed two possible mechanisms for the formation of iminium ions based on the two divergent pathways for the conversion of amine radical cations to iminium ions. The first mechanism is based on the pathway involving abstraction of a

• oxidizing than that of Ru(bpy)3 (E1/2*II/I = 0.77 V vs SCE). However, the two catalysts showed a divergent pattern of reactivity in the reaction. Ru(bpy)3 was the more active catalyst for hydrazines, whereas Ru(bpz)3 was more active for hydrazides. The use of MeOH in addition to CH3CN significantly

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

• Kegong Ji,
• Jonathan Nelson and
• Liming Zhang

Beilstein J. Org. Chem. 2013, 9, 1925–1930, doi:10.3762/bjoc.9.227

• rationalized as the results of divergent transformations of the α-oxo gold carbene B: the former is formed via a two-step 2,3-acetoxy migration [22][23], and the latter most likely via a concerted carbene 1,2-C–H insertion[2]. The selective formation of the Z isomer of 5a-OAc can be attributed to that B adopts

Gold-catalyzed oxycyclization of allenic carbamates: expeditious synthesis of 1,3-oxazin-2-ones

• Benito Alcaide,
• Pedro Almendros,
• M. Teresa Quirós and
• Israel Fernández

Beilstein J. Org. Chem. 2013, 9, 818–826, doi:10.3762/bjoc.9.93

• ) have been carried out at the PCM-M06/def2-SVP//B3LYP/def2-SVP level to gain more insight into the reaction mechanism of the above discussed gold-catalyzed divergent oxycyclization reaction. The corresponding computed reaction profiles of the model allene 1M with the model gold catalyst AuPMe3(OTf) are

• be concluded that the observed divergent cyclization finds its origin in the initial 6-endo versus 6-exo oxyauration reaction steps, with the former being kinetically favored whereas the latter is thermodynamically favored. At this point, it cannot be safely discarded that the formation of the

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• groups can be functionalized with various recognition elements to provide multiple final products from a common polymer intermediate in a divergent manner [7][8]. Telechelic polymers provide a means for further modifying the polymer with a variety of reporter molecules [6][7][9]. These polymers have been