First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• (96% ee) despite using the same procedure as for the reaction between (S)-(+)-5 and PBr3. In addition, bromination of (S)-(+)-5 under Appel reaction conditions employing tetrabromomethane (CBr4) as a halide ion source used along with triphenylphosphine (Ph3P) was also investigated. Although this

Synthesis of modified cyclic and acyclic dextrins and comparison of their complexation ability

• Kata Tuza,
• László Jicsinszky,
• Tamás Sohajda,
• István Puskás and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2014, 10, 2836–2843, doi:10.3762/bjoc.10.301

• synthetic route was worked out via bromination, benzylation, deacetylation and debenzylation to obtain the 2-hydroxypropyl maltooligomer counterparts. The complexation properties of non-modified and modified cyclic and acyclic dextrins were studied and compared by photon correlation spectroscopy (PCS) and

• chloroform/acetone for bromination, 85:15 v/v alcohol free chloroform:acetone for benzylation and 10:7 v/v dioxane:satd. aq ammonia for hydroxypropylation and debenzylation; visualization: 15% cc. H2SO4 in 96% EtOH. Synthesis of HP-maltooligomers 1-Bromo-peracetyl-maltooligomers, according to [14

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• treatment with phosphoryl chloride and N,N-dimethylformamide to give 3, which in turn was brominated with NBS (1.05 equiv) to yield compound 4. Both reactions proceeded in high yields: 90% for the formylation step and 88% for bromination. Compound 7 was prepared following the same procedure used to

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• conditions were used for the preparation of AHLs with unfunctionalized acyl chains in a convenient way. The brominated fatty acids 5, except the commercially available α-bromohexanoic acid (5a), were prepared by a Hell–Volhard–Zelinsky bromination of the corresponding fatty acid 4 with molecular bromine and

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• nortricyclenes using palladium and zinc powder from norbornadiene. The bromination of norbornene [30][31][32] is another route to the nortricyclenes. Here, in this study we report an efficient method for the synthesis of aryl- and vinyl-substituted tetrachloromethylenenortricyclenes from the Diels–Alder (DA

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• to regenerate the base precursor. Via a radical bromination, followed by a nucleophilic elimination under alkaline conditions, the alkane is oxidized to the alkene base precursor. These alkaline conditions and the four electron withdrawing ethoxy carbonyl groups (R1), prevent further bromination of

A versatile δ-aminolevulinic acid (ΑLA)-cyclodextrin bimodal conjugate-prodrug for PDT applications with the help of intracellular chemistry

• Chrysie Aggelidou,
• Theodossis A. Theodossiou,
• Antonio Ricardo Gonçalves,
• Mariza Lampropoulou and
• Konstantina Yannakopoulou

Beilstein J. Org. Chem. 2014, 10, 2414–2420, doi:10.3762/bjoc.10.251

• δ-position silenced, presented a completely straightforward precursor to 1 and proved to be amenable to coupling with 4 under various reaction conditions. Briefly [14], 8 was prepared from levulinic acid (5) through δ-bromination and concomitant methyl ester formation (compound 6), followed by

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• -Bromination with copper(II) bromide [20] gave 8 (96%, direct bromination of 6 gave poor yields). The TBS group was removed in 30% aqueous methanol containing 10–20% methylene chloride and several molar equivalents of potassium hydrogen sulfate to provide hydroxy bromo ketone 9 (yield, 75%) [21], which was

• with Friedel–Crafts acylation of 1-methoxynaphthalene (11) yielding 1-acetyl-4-methoxynaphthalene (12, 73%). α-Bromination with copper(II) bromide gave 13 (44%) which was converted to the phosphate ester using tetramethylammonium diethyl phosphate in dimethoxyethane (DME) at room temperature to give

• α-bromination to 17 (89%). TBS deprotection gave 2-bromo-1-(4-hydroxy-1-naphthyl)ethanone, (18, 59%) which was converted to diethyl (2-(4-hydroxynaphthalen-1-yl)-2-oxoethyl) phosphate (1,4-HNA DEP, 14a, 31%) with tetramethylammonium diethyl phosphate. Benzyl protected diethyl 2-(8-hydroxyquinolin-5

Syntheses of ¹⁵N-labeled pre-queuosine nucleobase derivatives

• Jasmin Levic and
• Ronald Micura

Beilstein J. Org. Chem. 2014, 10, 1914–1918, doi:10.3762/bjoc.10.199

• work-up and reversed-phase column chromatography (C18) (Scheme 2) [14]. Then, the α-bromo aldehyde 7 was obtained in two steps from commercially available 3-phthalimidopropan-1-ol that was oxidized using Dess–Martin periodinane. Subsequent in situ bromination of the 3-phthalimidopropan-1-al with

Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions

• Xuanshu Xia and
• Patrick H. Toy

Beilstein J. Org. Chem. 2014, 10, 1397–1405, doi:10.3762/bjoc.10.143

• reactions discussed above, some of these reactions did not proceed to completion, even when the reaction time was lengthened. Generally, it was observed that the bromination reactions afforded higher product yields than did the corresponding chlorination reactions (Table 2, entries 1–8), except when

Stereoselective synthesis of carbocyclic analogues of the nucleoside Q precursor (PreQ₀)

• Sabin Llona-Minguez and
• Simon P. Mackay

Beilstein J. Org. Chem. 2014, 10, 1333–1338, doi:10.3762/bjoc.10.135

• diastereospecific available [30] (Figure 4). The process started with a Wohl–Ziegler allylic bromination of cyclopentene. The volatile and unstable allylic halide 10 was immediately reacted with excess N,N-dibenzylamine and the resulting allylic amine 11 was obtained in good yield over two steps. Next, we

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• circumtrindene might also be brominated. Fullerenes are known to undergo bromine addition with elemental bromine in chlorinated solvents at room temperature [28]. To avoid the unwanted bromination at interior carbon atoms, the reaction conditions were carefully optimized (see Supporting Information File 1 for

Nonanebis(peroxoic acid): a stable peracid for oxidative bromination of aminoanthracene-9,10-dione

• Vilas Venunath Patil and
• Ganapati Subray Shankarling

Beilstein J. Org. Chem. 2014, 10, 921–928, doi:10.3762/bjoc.10.90

• Vilas Venunath Patil Ganapati Subray Shankarling Department of Dyestuff Technology, Institute of Chemical Technology, N. P. Marg, Matunga, Mumbai - 400019, India. Tel.: 91-22-33612708, Fax: 91-22-33611020 10.3762/bjoc.10.90 Abstract A new protocol for the oxidative bromination of aminoanthracene

• protocol has a broad scope for the bromination of various substituted and unsubstituted aminoanthracene-9,10-diones. Keywords: aminoanthracene-9,10-dione; benzanthrone; KBr; nonanebis(peroxoic acid); oxidative bromination; Introduction The brominated aminoanthracene-9,10-dione derivatives and

• benzanthrone are widely used as intermediates for pharmaceuticals [1][2][3], for medicinal applications [4], as dyes [5][6][7][8][9] and in Hg2+ ion sensors [10]. Although these bromo derivatives have a wide range of applications, it is difficult to carry out their bromination as the two carbonyl groups of

Visible-light photoredox catalysis enabled bromination of phenols and alkenes

• Yating Zhao,
• Zhe Li,
• Chao Yang,
• Run Lin and
• Wujiong Xia

Beilstein J. Org. Chem. 2014, 10, 622–627, doi:10.3762/bjoc.10.53

• Yating Zhao Zhe Li Chao Yang Run Lin Wujiong Xia State Key Lab of Urban Water Resource and Environment, The Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, China 10.3762/bjoc.10.53 Abstract A mild and efficient methodology for the bromination

• of phenols and alkenes has been developed utilizing visible light-induced photoredox catalysis. The bromine was generated in situ from the oxidation of Br− by Ru(bpy)33+, both of which resulted from the oxidative quenching process. Keywords: alkenes; bromination; phenols; photoredox catalyst

• ; visible light; Introduction Bromophenols serve as important synthetic intermediates for a variety of naturally occurring biologically active compounds and are also important constituents of industrial chemicals [1][2][3][4][5]. Thus, numerous methods were developed for the electrophilic bromination of

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• diphenylacetylene was used as starting material, different aryllithium compounds were employed to afford triarylethylene in 38% to 62% isolated yields after being quenched with HCl (Table 1, entries 1–4). Bromination of the reaction mixture by NBS instead hydrolysis afforded bromotriphenylethylene in 37% isolated

• instead of diphenylacetylene. After bromination by NBS (2 mmol), 3j was isolated in 36% yield. 1H NMR (300 MHz, CDCl3, Me4Si) δ 2.18 (s, 3H), 2.25 (s, 3H), 6.80–7.38 (m, 13H); 13C NMR (75 MHz, CDCl3, Me4Si) δ 21.3, 21.4, 122.1, 127.5, 128.2, 128.7, 128.8, 129.6, 130.3, 130.3, 136.7, 137.8, 138.4, 138.5

Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

• Fei Wang,
• Lingchun Li,
• Chuanfa Ni and
• Jinbo Hu

Beilstein J. Org. Chem. 2014, 10, 344–351, doi:10.3762/bjoc.10.32

• TMSCF3 from fluoroform (CF3H), which paved the way for the synthetic applications of TMSCF3 [38][39]. Moreover, the preparation of TMSCF2Br either by fluoro–bromo exchange reaction of TMSCF3 [34] or by bromination of TMSCF2H [34][40] has also been disclosed. To obtain TMSCF2Cl, we tried the halogen

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• to give pentacycle 172. Reduction of the nitro group was followed by Cbz-protection. Allylic alcohol 173 resulted from radical allylic bromination followed by displacement of bromine through water under silver-catalysis. Eschenmoser–Claisen rearrangement [148] led to the formation of the remaining

Synthesis and determination of the absolute configuration of (−)-(5R,6Z)-dendrolasin-5-acetate from the nudibranch Hypselodoris jacksoni

• I. Wayan Mudianta,
• Victoria L. Challinor,
• Anne E. Winters,
• Karen L. Cheney,
• James J. De Voss and
• Mary J. Garson

Beilstein J. Org. Chem. 2013, 9, 2925–2933, doi:10.3762/bjoc.9.329

• . The overall synthesis (Scheme 1) was adapted from Tsubuki et al. [21]. Furan-3-ylmethanol (4) was prepared in 78% yield by reduction of 2-furoic acid with LiAlH4 in dry diethyl ether, whereas geranyl bromide (5) was obtained through bromination of geraniol with carbon tetrabromide and

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• purification. Bromination was carried out using the method of Lester et al. [17], and while it was effective at small scales, larger scale (>150 mmol) reactions were violently exothermic. A modification of the reaction order reported earlier by Gershon and coworkers solved the problem [18]. Chlorobenzene was

Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C₃-building block

• Volker M. Schmiedel,
• Stefano Stefani and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2013, 9, 2564–2569, doi:10.3762/bjoc.9.291

• dihydrofurans 14 and 15 by oxidative azidation (see above) only led to very low yields of the desired α-azidotetrahydrofuranones (6%). The conditions obviously cause decomposition of the auxiliary. As an alternative, the electrophilic bromination of 15 with NBS and the subsequent substitution with sodium azide

• . Subsequent functionalization using oxidative azidation, as shown for methoxy-substituted dihydrofuran 8, did not give the expected α-azidotetrahydrofuranones in acceptable yields, but electrophilic bromination and subsequent substitution with sodium azide turned out to be a good alternative for the synthesis

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

• from 9,10-dihydro-9,10-[1',2']benzenoanthracene-2,3,6,7,14,15-hexacarboxylic acid through its hexaethyl ester. However, their yields were very low, 17% in the first step and 26% in the subsequent LiAlH4 reduction/HBr bromination. Moreover 9,10-dihydro-9,10[1',2']-benzenoanthracene-2,3,6,7,14,15

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

• Knoevenagel adduct 2.12 and methyl butynoate 2.13 (Scheme 25) [68]. The reaction is reported to progress in high regioselectivity (>50:1) albeit in moderate isolated yield. Following debenzylation of the Diels–Alder product a selective allylic bromination was achieved again in good selectivity (>80:20

• dihydropyridine. This regioselective bromination reaction was studied in some detail by the Warner–Lambert Company and is reported to give superior outcomes when compared to the direct Hantzsch synthesis of non-symmetrical dihydropyridines with respect to product yield (70–90% vs 10–30%) and ease of purification

Flexible synthesis of anthracycline aglycone mimics via domino carbopalladation reactions

• Markus Leibeling and
• Daniel B. Werz

Beilstein J. Org. Chem. 2013, 9, 2194–2201, doi:10.3762/bjoc.9.258

• NCS and NBS are able to convert the silane into a reactive species. However, the yields were low in all cases. Changing the bromination reagent to elemental bromine significantly improved the yields (Table 1, entries 4 and 5) [36]. Diethyl ether proved to be important as a solvent, the change to THF

• led to a total decomposition – most probably due to ring-opening reactions with bromosilanes [37]. Further, we investigated the influence of the amount of bromine on the reaction and concluded that stoichiometric quantities entirely fulfill the demands of the bromination (Table 1, entries 7 and 8

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

• ]. The synthesis commenced with the preparation of the isoindolinone building block 134. Friedel–Crafts acetylation of 132, followed by a Lieben haloform degradation gave the corresponding acid, which after methylation yielded 133. Bromination and lactam formation afforded isoindolinone 134. The

• in the total synthesis of 193 by Schmalz (Scheme 24) [149]. Reaction of lithiated 188 (three steps from commercially available 5-methylresorcinol) with the aldehyde 189 (double bromination of 3,5-dimethoxybenzaldehyde) gave the racemic alcohol 190. Oxidation to the benzophenone, installation of the

Total synthesis of (−)-epimyrtine by a gold-catalyzed hydroamination approach

• Thi Thanh Huyen Trinh,
• Khanh Hung Nguyen,
• Patricia de Aguiar Amaral and
• Nicolas Gouault

Beilstein J. Org. Chem. 2013, 9, 2042–2047, doi:10.3762/bjoc.9.242

• stereospecifically the corresponding piperidone 4 in 80% yield. Subsequent bromination with CBr4 in the presence of PPh3 (Appel reaction) gave 5 in 84% yield. Finally, deprotection with 1 M SnCl4 in dichloromethane then neutralization by using K2CO3 afforded the final product (−)-epimyritine in a 80% yield. N-Cbz