Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• behavior in fluorination in view of selectivity and to explore substrate dependency and chemodifferentiation. Based on the different stereochemical structures of the selected model diols as well as the nature of the N-protecting group used, we expected differences in their chemical behavior under

Synthesis of ergostane-type brassinosteroids with modifications in ring A

• Vladimir N. Zhabinskii,
• Darya A. Osiyuk,
• Yuri V. Ermolovich,
• Natalia M. Chaschina,
• Tatsiana S. Dalidovich,
• Miroslav Strnad and
• Vladimir A. Khripach

Beilstein J. Org. Chem. 2017, 13, 2326–2331, doi:10.3762/bjoc.13.229

• ,3α-, and 2β,3β-dihydroxy-, 3-keto-, 3α- and 3β-hydroxy-, 2α-hydroxy-3-keto-) were synthesized from 2α,3α-diols in a few simple steps (Corey–Winter reaction, epoxidation, oxidation, hydride reduction, etc.). Keywords: biosynthetic precursors; brassinosteroids; diols; epibrassinolide; epicastasterone

• -keto-22,23-diols was synthesized and assessed for biological activities in non-plant models. Some of the studied compounds showed a marked cytotoxicity against human cancer cell lines MCF-7 and LNCaP [11][12][13]. We tested two approaches for the transformation of epicastasterone (1) and

• the contrary, no correlation was observed between the corresponding protons in compound 22, which is consistent with the α-orientation of the epoxide ring. 2β,3β-, 2β,3α- and 2α,3β-diols of type 6–8 Experiments on the identification of steroidal phytohormones in immature seeds of Phaseolus vulgaris

Remarkable functions of sn-3 hydroxy and phosphocholine groups in 1,2-diacyl-sn-glycerolipids to induce clockwise (+)-helicity around the 1,2-diacyl moiety: Evidence from conformation analysis by ¹H NMR spectroscopy

• Yoshihiro Nishida,
• Mengfei Yuan,
• Kazuo Fukuda,
• Kaito Fujisawa,
• Hirofumi Dohi and
• Hirotaka Uzawa

Beilstein J. Org. Chem. 2017, 13, 1999–2009, doi:10.3762/bjoc.13.196

• Equation 2 [18]. From the vicinal coupling constants (3J Hz) of H1proR and H1proS signals, the fractional populations (%) of the three staggered conformers are calculated. Equation 1 is a standard equation, in which the three staggered conformers have the dihedral angles of ± 60° or 180° around 1,2-diols

Selective enzymatic esterification of lignin model compounds in the ball mill

• Ulla Weißbach,
• Saumya Dabral,
• Laure Konnert,
• Carsten Bolm and
• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1788–1795, doi:10.3762/bjoc.13.173

• matched/mismatched interactions of the diastereomeric diols and the chiral biocatalyst. Similarly, the unsubstituted model compound 1e reacted smoothly to give 3e in 92% yield. Purification of 3e was done by filtration through a pad of celite, since it proved unstable towards standard purification

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

Synthesis of ribavirin 2’-Me-C-nucleoside analogues

• Fanny Cosson,
• Aline Faroux,
• Jean-Pierre Baltaze,
• Jonathan Farjon,
• Régis Guillot,
• Jacques Uziel and
• Nadège Lubin-Germain

Beilstein J. Org. Chem. 2017, 13, 755–761, doi:10.3762/bjoc.13.74

• with tetrabutylammonium fluoride leading to the mixture of diols 17 and 18 in quantitative yield which were easily separated (Scheme 3). Finally, the aminolysis of compound 17 followed by catalytic hydrogenolysis in the presence of palladium chloride led to the desired compound 3 [22] (Scheme 4

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

• set for the central dihydroxylation reaction that would give access to key intermediates 20 and 21 (Scheme 4). To our delight dihydroxylation with potassium osmate in the presence of citric acid was smooth and gave excellent yields of diols 20 and 21 [11]. Diols 20 and 21 were found to be unstable

Studies directed toward the exploitation of vicinal diols in the synthesis of (+)-nebivolol intermediates

• Runjun Devi and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2017, 13, 571–578, doi:10.3762/bjoc.13.56

• heterocycles has been tremendous, its synthetic utility toward chiral benzo-annulated heterocycles is relatively limited. Thus, in the search for wider applications of Sharpless asymmetric dihydroxylation-derived diols for the synthesis of benzo-annulated heterocycles, we report herein our studies in the

• , method 3) whereupon the overall yield of the reaction sequence diminished [11]. On the other hand, the Sharpless asymmetric dihydroxylation (SAD) has been a workhorse as a synthetic tool for accessing enantiopure vicinal diols [21]. The extensive work in this field has resulted in the discovery of a

• superior in terms of operational simplicity as SAE, it can be run at 0 °C in water as a co-solvent and under an atmosphere open to air. The application of SAD-derived vicinal diols in the synthesis of acyclic molecules and saturated heterocycles has been astonishing. However, their utilities in the

Orthogonal protection of saccharide polyols through solvent-free one-pot sequences based on regioselective silylations

• Serena Traboni,
• Emiliano Bedini and
• Alfonso Iadonisi

Beilstein J. Org. Chem. 2016, 12, 2748–2756, doi:10.3762/bjoc.12.271

• saccharide alcohols [34], the first catalytic tin-mediated procedure for regioselective benzylation/allylation of hydroxy groups incorporated into vicinal diols [35], and three alternative acetalation protocols [36]. Besides the avoided use of solvents, these approaches appear advantageous owing to their

A versatile route to polythiophenes with functional pendant groups using alkyne chemistry

• Xiao Huang,
• Li Yang,
• Rikard Emanuelsson,
• Jonas Bergquist,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265

• light yellow oil by chromatography with a yield of 64%. The yield of the transetherification product was influenced by two factors. Substrate concentrations below 0.5 M resulted in much less polymerization, leaving more diols for transetherification. However, still lower concentrations of less than 0.1

• % could be obtained, but this would not be sufficient for large scale production, besides considering the environmental impact of requiring a halogenated solvent. Comparing the structural difference between diols 2 and 7, these results emphasized that the isolation of the alkyne from the ethylenediol by

Formose reaction controlled by boronic acid compounds

• Toru Imai,
• Tomohiro Michitaka and
• Akihito Hashidzume

Beilstein J. Org. Chem. 2016, 12, 2668–2672, doi:10.3762/bjoc.12.263

• optimizing the conditions of the formose reaction [6][7][8][9][10][11][12][13][14][15]. However, the selective formose reaction is still an important subject of investigation [16]. It is known that boronic acid compounds form esters with diols, e.g., sugars [17][18]. Boronic acid compounds may thus stabilize

Synthesis of polyhydroxylated decalins via two consecutive one-pot reactions: 1,4-addition/aldol reaction followed by RCM/syn-dihydroxylation

• Michał Malik and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2016, 12, 2602–2608, doi:10.3762/bjoc.12.255

• ]. After desilylation followed by protection of the free hydroxy with a benzoyl group and deprotection of the isopropylidene moiety, diols 20 and 24 were obtained. With α,β-unsaturated ketones 17 and 18 and two enantiomeric, optically pure aldehydes (R)- and (S)-10 in hand, we started to study the 1,4

• the subsequent syn-dihydroxylation with NaIO4 as a stoichiometric oxidant in the presence of catalytic amounts of CeCl3 (15 mol %). As a result, in the case of diolefin 25 as substrate, a separable mixture of diols (dr = 8:1; 27 being the major isomer) was obtained in fair yield (56%). The same

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• isosorbide was almost quantitative (95.2%). Similarly poly(aliphaticdiol-co-isosorbide carbonate)s were prepared via melt polycondensation of DMC with isosorbide and several aliphatic diols employing Li(acac) and the TiO2/SiO2-based catalyst (Scheme 4) [85]. High-molecular-weight (Mw = 32,600) and optically

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• prepared from commercially available neryl acetate (15). The auxiliary-controlled, permanganate-promoted oxidation of diene 16 proceeded selectively at low temperatures, affording the corresponding diastereomeric THF diols as an inseparable mixture (dr 7:1, major stereoisomer shown in Scheme 6). Compound

• [84]. Thus, the corresponding THF diols were obtained in 55% yield. In addition to the desired THF diol 28a for the total synthesis of cis-solamin A (29), small amounts of its diastereoisomer 28b were isolated (dr 10:1, Scheme 8 left). Similar permanganate-mediated oxidative cyclizations were also

• [92][97]. In this case, two permanganate-promoted type A oxidative cyclization reactions were used to establish the two THF rings of this acetogenin (Scheme 11). Both THF diols 43 and 47 were isolated as pure diastereoisomers with high diastereocontrol (dr 9:1 for 43 and dr 8.7:1 for 47, respectively

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• should therefore implement greener reactions, such as the direct carboxylation of diols by CO2, for which however, effective catalysts are currently not available. The Asahi Kasei process also highlights that the synthesis of DMC by transesterification of ethylene carbonate with methanol does not

• synthesize organic carbonates consists in the acid or base-catalyzed transesterification of dimethyl carbonate (DMC), the simplest organic carbonate, with alcohols R–OH or diols to yield either acyclic organic carbonates or cyclic carbonates, respectively (Scheme 8). A literature survey on the synthesis of

• diols can be carried out in the presence of basic (e.g., tertiary phosphines and amines, alkali metal hydroxides, alkoxides, halides, carbonates, alkali metal exchanged faujasites and hydrotalcites) or acidic catalysts or co-catalysts, and under thermal (non-catalytic) conditions. All applicable

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• treatment of unsubstituted bicyclic endoperoxides 229 by bases affords 4-hydroxyenones 230 [344] which are useful precursors in asymmetric organic syntheses. Alternative synthetic methods towards this class of compounds normally require a metal-catalyzed or biocatalyzed oxidation of diols 231 in an

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• application to the synthesis of high-boiling diols is more difficult due to their low-vapour pressures. Recently Cohen et al. synthesised mixtures of IPNs via the reaction of (±)-isoprene epoxide with pre-ground bismuth(III) nitrate [19]. Using a preliminary ’flash’ purification (silica gel) afforded an

• the diols or execute a regioselective 1° or 2° mono-O-nitration was not. Eliminating the former problem Hodgson et al. [26] reported rac-17 could be generated from cheap, commercially available 2,5-dihydrofuran which, after epoxidation with meta-chloroperbenzoic acid (mCPBA), afforded epoxide 21 in a

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• asymmetric aldol reaction of trifluoromethyl α-fluorinated β-keto gem-diols with isatins, generating 3-hydroxyoxindoles in high yields (up to 99%) and with excellent enantioselectivities (up to 98% ee, Scheme 28) [45]. The reaction was performed at room temperature using AcOH as the additive in the presence

• of 10% of catalyst loading. Interestingly, the protocol employed gem-diols as equivalents of fluorinated aryl/alkyl methyl ketone enolates for the C–C bond formation accompanied the release of trifluoroacetate. This method showed a broad substrate scope including gem-diols with phenyl rings

• , heterocyclic groups and aliphatic groups. A plausible mechanism was proposed as shown in Scheme 29. The thiourea NH moieties and the tertiary amino group of the catalyst activated the carbonyl groups of isatin and the α-protons of gem-diols, respectively through hydrogen bond interactions. The α-proton of gem

One-pot synthesis of enantiomerically pure N-protected allylic amines from N-protected α-amino esters

• Gastón Silveira-Dorta,
• Sergio J. Álvarez-Méndez,
• Víctor S. Martín and
• José M. Padrón

Beilstein J. Org. Chem. 2016, 12, 957–962, doi:10.3762/bjoc.12.94

• . Disappointingly, the product (E)-4a was obtained in low yield although in excellent (dia)stereoselectivity. In the synthesis of anti-2-amino-1,3-diols, we reported earlier that the addition of DIBAL-H must be done necessarily in two portions [16]. Thus, fine-tuning of the reduction conditions was required in

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• aldehydes in the presence of metal halides to furnish tetrahydro-2H-pyran-2,4-diols in a highly diastereoselective manner, is investigated thoroughly by experiments and computations. The reaction was also successfully implemented on a flow micro reactor system. Keywords: DFT; diastereoselective reaction

• the years [31]. We have already reported a domino aldol–aldol–hemiacetal process that furnishes racemic tetrahydro-2H-pyran-2,4-diols in a highly stereoselective manner (Scheme 1) [30][31][32][33][34][35][36][37]. In this paper, the domino aldol–aldol–hemiacetal reaction involving several metals (Al

• . The larger the amount of aldehyde in the reaction, the higher is the yield of monoaldol product 6a, which supports a thermodynamically controlled equilibrium as further confirmed by the following observations: (1) with gallium(III) two diastereomeric tetrahydro-2H-pyran-2,4-diols are formed at 0 °C

Iridium/N-heterocyclic carbene-catalyzed C–H borylation of arenes by diisopropylaminoborane

• Mamoru Tobisu,
• Takuya Igarashi and
• Naoto Chatani

Beilstein J. Org. Chem. 2016, 12, 654–661, doi:10.3762/bjoc.12.65

• ) complex with 1,3-dicyclohexylimidazol-2-ylidene is found to efficiently catalyze the borylation of arenes and heteroarenes. The resulting aminoborylated products can be converted to the corresponding boronic acid derivatives simply by treatment with suitable diols or diamines. Keywords: boronic acid; C–H

• the synthetic advantage of allowing various substituents to be introduced onto the boron atom during the work-up stage simply by changing the reagents added. For example, addition of different diols delivered the corresponding boronic esters 10-Bnep and 10-Bmep (Scheme 2, bottom). It was also possible

Self and directed assembly: people and molecules

• Tony D. James

Beilstein J. Org. Chem. 2016, 12, 391–405, doi:10.3762/bjoc.12.42

• elements and developed an AND logic system for “cations” and “diols” (Figure 6) [51][52]. In 1998 Michael Bell from Beckman Coulter approached me about working together on a fluorescent glucose sensor system. Therefore, in July and few weeks after the birth of my son Joseph “Joey” Hiro Furukawa James, I

• the enantiomeric excess of the original scalemic mixture of binol (diol) or amine (Figure 15). The three-component system was very versatile and we could use the complexes to determine the enantiomeric excess (ee) of amines [69][70], diamines [71], amino alcohols [72], hydroxylamines [73] and diols

Highly stable and reusable immobilized formate dehydrogenases: Promising biocatalysts for in situ regeneration of NADH

• Barış Binay,
• Dilek Alagöz,
• Deniz Yildirim,
• Ayhan Çelik and
• S. Seyhan Tükel

Beilstein J. Org. Chem. 2016, 12, 271–277, doi:10.3762/bjoc.12.29

• [30]. In this study, Immobead 150 support was kept in 1 M acetic acid solution to produce vicinal diols and then the formed diols were oxidatively cleaved with NaIO4 to produce aldehyde groups onto the support (Figure 1c). The amount of bound protein was determined as 90% of the initial loading

Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation

• Jochen Kraft,
• Martin Golkowski and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 166–171, doi:10.3762/bjoc.12.18

• acidic conditions gave the corresponding diols 3 [20] and 4 as anomeric mixtures. Condensation of the latter with thiocyanic acid in a Ritter-type reaction according to a slightly modified procedure described by Tatibouët et al. [21] gave an anomeric mixture of 1,3-oxazolidin-2-thiones 5 and 6