Assembly of synthetic Aβ miniamyloids on polyol templates

• Sebastian Nils Fischer and
• Armin Geyer

Beilstein J. Org. Chem. 2015, 11, 2646–2653, doi:10.3762/bjoc.11.284

• avoided only when two different reactive groups are employed; that is why the reversible esterification between boronic acids and diols appeared an attractive solution to us. In a first approach, we planned to condense short peptide boronic acids with polyol templates for the assembly of an Aβ-dimer. The

• diols on the template must be separated from each other far enough to exclude the simultaneous formation of mixtures of 5- and 6-membered boronic esters. However, the oligosaccharides, which are available with a consistent oligomerization degree of dimer, trimer, tetramer and higher, are known to have

Recent advances in copper-catalyzed asymmetric coupling reactions

• Fengtao Zhou and
• Qian Cai

Beilstein J. Org. Chem. 2015, 11, 2600–2615, doi:10.3762/bjoc.11.280

• -halophenoxyl)-1,3-diols by the same group [54]. However, the palladium catalytic systems suffered from limited substrate scope and poor efficiency and enantioselectivity for the formation of quaternary stereocenters. Recently, Cai et al. carried out such couplings using a CuI/cyclized diamine catalytic system

Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines with aryl iodides

• Svetlana P. Panchenko,
• Alexei D. Averin,
• Maksim V. Anokhin,
• Olga A. Maloshitskaya and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2015, 11, 2297–2305, doi:10.3762/bjoc.11.250

• the literature. One of them employs an iridium-based catalyst with amidophosphonate as the ligand which allows to convert aminoalcohols into N-monoaryl-substituted diamines by the reaction with arylamines [20]. Another method uses a bimetallic catalyst (Pt–Sn/γ-Al2O3) in the reactions of diols with

Design and synthesis of propellane derivatives and oxa-bowls via ring-rearrangement metathesis as a key step

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1727–1731, doi:10.3762/bjoc.11.188

• with a minor amount of compound 9 (8%). The formation of compound 9 may be explained on the basis of a retro-DA reaction [36] followed by reduction and elimination. In the same way, reduction of C-allyl compound 4b under similar reaction conditions gave diol 8b in 88% yield. In the next step, diols 8a

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• beginning of the use of lipases in organic solvents. In 1984 Okumura et al. [48] produced oligomers of several dicarboxylic acids (C6 to C14) in combination with several diols (C2 and C3). Since then the use of lipase-catalyzed preparation of polymers has grow very much and has been reviewed many times (see

• -mercaptosuccinate) could be oxidized by air in DMSO to form a cross-linked insoluble material (Figure 12). In a subsequent paper, the same laboratory prepared different mercaptosuccinate polymers with several diols. In addition they showed that the material cross-linked by air oxidation could be reversibly reduced

• by tributylphosphine to recover the reduced soluble polymer [64]. In a recent review, Khan et al. summarized the synthesis of polymers based on C-5-substituted isophthalates (36, Figure 13) and diols [65]. Using hydroxy or amine groups at C-5 afforded polymers, which could be further modified by

Preparative semiconductor photoredox catalysis: An emerging theme in organic synthesis

• David W. Manley and
• John C. Walton

Beilstein J. Org. Chem. 2015, 11, 1570–1582, doi:10.3762/bjoc.11.173

• representative range of aldehydes and ketones using dispersions of P25 with soft UVA in MeCN/MeOH (9:1) as solvent [79]. Aromatic aldehydes yielded the corresponding primary alcohols along with pinacol byproducts. Control experiments confirmed that these diols were formed by the well-known photochemical coupling

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

• Ivan Šnajdr,
• Kamil Parkan,
• Filip Hessler and
• Martin Kotora

Beilstein J. Org. Chem. 2015, 11, 1392–1397, doi:10.3762/bjoc.11.150

• -deoxyribosides [15]. Finally, there is also a method utilizing an excess of vinylmagnesium bromide in the reaction with 3,5-bis-O-TBDPS-protected 2-deoxy-D-ribofuranose giving rise to a mixture of diastereoisomeric diols. The diasteroisomers were separated and cyclized in the presence of MsCl to the

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• , dibromide 83 was converted to bis-aldehyde 84. Finally, McMurry coupling of dialdehyde 84 provided the cyclophane derivative 85 (28%). Yamoto and co-workers have reported the synthesis of medium-sized cyclophanes, [2.n]metacyclophane-1,2-diols 86 and 87 by using the McMurry coupling as a key step (Figure 8

• was explained on the basis of a tandem isomerization of a terminal double bond followed by the macrocyclization with G-II (13). Finally, the oxidation of diols 186 and 189 generated cyclophanes 187 and 190, respectively (Scheme 30). Guan and coworkers [154] have reported a novel synthetic approach to

Novel stereocontrolled syntheses of tashiromine and epitashiromine

• Loránd Kiss,
• Enikő Forró and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2015, 11, 596–603, doi:10.3762/bjoc.11.66

• convenient route for the preparation of N-heterocyclic β-amino acid derivatives [40][41] or for the stereocontrolled synthesis of functionalized cispentacins [42] and their acyclic counterparts [43][44] (Figure 5). The oxidative ring cleavage of various vicinal diols and the transformation of the resulting

• dialdehyde intermediates has been efficiently applied in recent years for the synthesis of a series of valuable organic molecules [45][46][47][48][49][50][51][52]. In particular, Davies and co-workers have utilized the oxidative ring opening of cyclic vicinal diols followed by ring closure for access to

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• method to synthesize protected syn-1,3-diols by performing intramolecular conjugate additions to a series of α,β-unsaturated esters and amides [71] (Scheme 8). Upon treatment of 24 with KHMDS and benzyaldehyde, a hemiacetal forms which provides the alkoxide nucleophile for the DCA reaction. These

Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• reflectance of the complex decreased while transmittance increased with increased annealing temperature. Our easy synthesis of dithiin-containing compounds led to the production of various BEDT-TTF analogues, comprising monophenyldithiin, diphenyldithiin, diphenylthiophene and diols [40][46][53]. While

Anionic sigmatropic-electrocyclic-Chugaev cascades: accessing 12-aryl-5-(methylthiocarbonylthio)tetracenes and a related anthra[2,3-b]thiophene

• Laurence Burroughs,
• John Ritchie,
• Mkhethwa Ngwenya,
• Dilfaraz Khan,
• William Lewis and
• Simon Woodward

Beilstein J. Org. Chem. 2015, 11, 273–279, doi:10.3762/bjoc.11.31

• Laurence Burroughs John Ritchie Mkhethwa Ngwenya Dilfaraz Khan William Lewis Simon Woodward School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom 10.3762/bjoc.11.31 Abstract 1,4-Diols resulting from the double addition of ArCCLi (Ar = Ph

• Discussion Investigation of the chemistry of Scheme 2 commenced with the preparation of the required diols 8 through simple acetylide addition to o-phthalaldehyde (60–91% yield, see Supporting Information File 1). All of the additions proceeded in high yield, but under all conditions tried, no strong bias to

• equivalent trend in diols 8b–f where two distinct sets of equivalent signals are seen δH 6.14–6.20 and δH 6.23–6.35. On this basis we assign the higher chemical shift signal to the meso diastereomer. Cascade optimisation (Table 1) was carried out using 8a in THF unless otherwise stated. Typically diol 8a (ca

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• convergent approach) and 29 [9] (Scheme 6). Based on ketones 27a–c and diols 28, 29 we obtained ARs 32a–c in two steps consisting of the established double activation acetalization [8] and the CuAAC, catalyzed by Cu/C, with moderate yields (Scheme 7). As mentioned above this sequential approach failed in the

NAA-modified DNA oligonucleotides with zwitterionic backbones: stereoselective synthesis of A–T phosphoramidite building blocks

• Boris Schmidtgall,
• Claudia Höbartner and
• Christian Ducho

Beilstein J. Org. Chem. 2015, 11, 50–60, doi:10.3762/bjoc.11.8

• with ammonium fluoride in methanol at elevated temperature, which afforded diols (S)-27 and (R)-27, each in 66% yield. DMTr protection under standard conditions then provided intermediates (S)-28 and (R)-28 in yields of 72% and 81%, respectively. Finally, phosphitylation of the 3'-hydroxy group gave

Thermal and oxidative stability of the Ocimum basilicum L. essential oil/β-cyclodextrin supramolecular system

• Daniel I. Hădărugă,
• Nicoleta G. Hădărugă,
• Corina I. Costescu,
• Ioan David and
• Alexandra T. Gruia

Beilstein J. Org. Chem. 2014, 10, 2809–2820, doi:10.3762/bjoc.10.298

• isoaromadendrene oxide (22) (up to 0.2%), or the corresponding diols (up to 0.1%). Obtaining of O. basilicum L. essential oil/β-CD complex The O. basilicum L. essential oil/β-CD complex was obtained by using the controlled crystallization method from an ethanol/water suspension (due to the lower water solubility

Design and synthesis of novel bis-annulated caged polycycles via ring-closing metathesis: pushpakenediol

• Sambasivarao Kotha and
• Mirtunjay Kumar Dipak

Beilstein J. Org. Chem. 2014, 10, 2664–2670, doi:10.3762/bjoc.10.280

• synthesis of heptacyclic diol 22. The synthesis of diallylated hexacyclic diols. The attempted synthesis of heptacyclic diol via ring-rearrangement metathesis. Supporting Information Supporting Information File 428: Copies of 1H, 13C NMR and HRMS spectra for all new compounds. Acknowledgements We would

Regio- and stereoselective synthesis of new diaminocyclopentanols

• Evgeni A. Larin,
• Valeri S. Kochubei and
• Yuri M. Atroshchenko

Beilstein J. Org. Chem. 2014, 10, 2513–2520, doi:10.3762/bjoc.10.262

• of stereoselective epoxide opening of these cyclic amine derivatives are limited to the preparation of the corresponding diols under acidic conditions [23]. Other reported strategies involve the formation of diaminocyclohexanols from epoxides under basic conditions [24] or by activating the epoxides

De novo macrolide–glycolipid macrolactone hybrids: Synthesis, structure and antibiotic activity of carbohydrate-fused macrocycles

• Richard T. Desmond,
• Anniefer N. Magpusao,
• Chris Lorenc,
• Jeremy B. Alverson,
• Nigel Priestley and
• Mark W. Peczuh

Beilstein J. Org. Chem. 2014, 10, 2215–2221, doi:10.3762/bjoc.10.229

• remainder of the synthesis separately. Transacetalization of the C4,C6-O-benzylidene protecting group in methanol provided diols 9a and 9b, respectively in nearly quantitative yields. Chemoselective, DCC-mediated acylation of the primary alcohol group of 9a and 9b at 0 °C with pentenoic acid gave 10a (58

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• benzylic alcohols, α-hydroxycarbonyl, and α-cyanohydrin compounds. Moreover, the selective catalytic monoacylation of diols is possible, thus allowing efficient monodeoxygenations as exemplified in the conversion of (+)-diethyl tartrate to unnatural (+)-diethyl malate. Results and Discussion Following the

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

Palladium-catalysed cyclisation of alkenols: Synthesis of oxaheterocycles as core intermediates of natural compounds

• Miroslav Palík,
• Jozef Kožíšek,
• Peter Koóš and
• Tibor Gracza

Beilstein J. Org. Chem. 2014, 10, 2077–2086, doi:10.3762/bjoc.10.216

• tertiary allylic alcohol was performed in a two-step sequence. The addition of methyllithium to ester Z-17 and following deprotection of the corresponding alcohol 27 with aqueous acetic acid afforded tetraol 28 in good yield. Substrates syn-diols 33–35 (not bearing an α-O-protected group) were prepared in

• reaction with the corresponding Grignard reagent in the presence of CeCl3·2LiCl providing diols 33–35 in good overall yields and high diastereoselectivity (d.r. >20:1). Additionally, allylic acetate 37 was obtained starting from 33 in a seven-step sequence in 30% overall yield. The acetonisation of hydroxy

Reaction of selected carbohydrate aldehydes with benzylmagnesium halides: benzyl versus o-tolyl rearrangement

• Maroš Bella,
• Bohumil Steiner,
• Vratislav Langer and
• Miroslav Koóš

Beilstein J. Org. Chem. 2014, 10, 1942–1950, doi:10.3762/bjoc.10.202

• formation (via an intermediate F) of 1-methyl-2-substituted-naphthalenes I, analogues of o-tolyl derivatives 4 and 5 (Scheme 2, final step of path 1), which were in present study, by contrast, isolated as stable products. Moreover, path 2 in Scheme 2 can be excluded, since no diols of type C (analogues of

• diols H in Scheme 3) were detected in the reaction mixture. To extend and confirm these observations, the analogous addition of 1 as well as 2 to another two representative carbohydrate aldehydes – 3-O-benzyl-1,2-O-isopropylidene-α-D-xylo-pentodialdo-1,4-furanose and 1,2:3,4-di-O-isopropylidene-α-D

Facile synthesis of 1-alkoxy-1H-benzo- and 7-azabenzotriazoles from peptide coupling agents, mechanistic studies, and synthetic applications

• Mahesh K. Lakshman,
• Manish K. Singh,
• Mukesh Kumar,
• Raghu Ram Chamala,
• Vijayender R. Yedulla,
• Domenick Wagner,
• Evan Leung,
• Lijia Yang,
• Asha Matin and
• Sadia Ahmad

Beilstein J. Org. Chem. 2014, 10, 1919–1932, doi:10.3762/bjoc.10.200

• hydroxy group, in good yields. In these reactions minor amounts of products arising by reaction at both hydroxy groups were observed. Similarly, reactions of 3-butenol gave products 4a and 4b in good to high yields, which were converted to the acyclic ribonucleoside-like diols (±)-5a and (±)-5b

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• and protection of 12a to 1,2-oxazine derivative 13. Conditions: a) 1. SnCl4, CH3CN, 4 h, −30 °C → rt; 2. TBSCl, imidazole, THF, 4 h, rt; b) NaBH4, EtOH, 4 h, −40 °C, 72%, dr 81:19; c) L-selectride, THF, 2 h, −10 °C, 73%, only 12a; d) TBSOTf, 2,6-lutidine, THF, 2 h, 0 °C. Synthesis of bicyclic diols 15

Aryl substitution of pentacenes

• Andreas R. Waterloo,
• Anna-Chiara Sale,
• Dan Lehnherr,
• Frank Hampel and
• Rik R. Tykwinski

Beilstein J. Org. Chem. 2014, 10, 1692–1705, doi:10.3762/bjoc.10.178

• purification step of the intermediate diols. Once formed, pentacenes 3a–h were obtained in moderate yield over two steps, as deep-blue solids. To expand the π-system in a linear fashion along the short molecular axis of the pentacene core, the general procedure described above was changed slightly, and ketone