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

• tetradentate ligands that were prepared by two CuAAC reactions in a one-pot procedure [39]. As shown in Scheme 19, these ligands exhibited good coordination properties to various metals, and the corresponding Mn(II) complexes showed good catalytic activity for the epoxidation of various aliphatic terminal

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• rearrangement [41] to afford an aldehyde that was converted to dimethylacetal 60. The following epoxidation proceeded with good stereoselectivity (α/β ≈ 11:1) and the regioselective opening of the epoxide moiety using lithium cyanide afforded a β-hydroxy nitrile in a trans-diaxial arrangement. Under basic

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• sesterfisherol (59, Scheme 10), the product of a bifunctional sesterterpene cyclase (C25) from Neosartorya fischeri [69]. In this case, [1-13C,2H3]acetate was fed and the resulting labeling pattern of an epoxidation product was analyzed by 13C NMR, revealing a loss of deuterium from carbons C-2, C-6 and C-10 by

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• chromatographic separation of the diastereomeric mixtures. In contrast, we have shown that the Katsuki–Sharpless epoxidation of (+)-neoisopulegol (4) is much more selective [9]. In the following we describe an improved version of our previously reported synthesis of 1. First we have focused our initial efforts on

• epoxidation of 5 with tert-butylhydroperoxide (TBHP) in toluene gave 6 ([α]D +34.2° (c 1.3, CHCl3)) in 95% yield [9][22]. Then, the diol 7 was obtained in 85% yield from the reduction of epoxide 6 with LiAlH4 in THF at 0 °C. The diol 7 was easily purified by crystallization (85% yield, n-hexane at −50 °C up

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

• step sequence of a Weinreb amide formation 228, epoxidation, and double addition of the vinyl Grignard 229 to generate the advanced intermediate 230. Finally, RCM of diolefin 230 under high dilution conditions afforded muscopyridine (73) (Scheme 37). Hagiwara and co-workers [173] have synthesized

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• employed. Treatment of tetraene 19 with excess bromine provided tetrabromide 25. In epoxidation reactions, both with meta-chloroperbenzoic acid (MCPBA) and dimethyldioxirane (DMDO) two model oligoenes were studied: triene 7 and tetraene 19. Whereas 7 furnished the rearrangement product 31 with MCPBA, it

• . Exploratory photochemical studies were carried out with tetraene 19 as the model compound. On irradiation this reacted with oxygen to the stable endo-peroxide 52. Keywords: bromination; Diels–Alder reactions; epoxidation; photochemistry; polyolefins; reactivity; hydrogenation; Introduction Several years ago

• , resulting in the overall formation of 1,x-bromine adducts. Epoxidations Epoxidation reactions of highly substituted dienes have been carried out by us and by others, and it has been demonstrated that whenever competing reaction pathways exist, it is usually the more highly substituted double bond that is

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• . Results and Discussion Our first attempt to prepare hydrocarbon 4 started from indene (6, Scheme 2). Epoxidation with m-chloroperbenzoic acid (MCPBA) according to a literature method [15] yielded the epoxide 7 in meager yields (Scheme 2). The methylation of 7 to 8 was achieved by the treatment with

Switching the reaction pathways of electrochemically generated β-haloalkoxysulfonium ions – synthesis of halohydrins and epoxides

• Akihiro Shimizu,
• Ryutaro Hayashi,
• Yosuke Ashikari,
• Toshiki Nokami and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2015, 11, 242–248, doi:10.3762/bjoc.11.27

• epoxidation using conventional reagents such as m-chloroperoxybenzoic acid (mCPBA) which epoxidizes alkenes from the less hindered face [33][34]. In this reaction, Br+ adds to the C–C double bond of 2g from the less hindered face to form the corresponding three-membered ring bromonium ion intermediate

Electrochemical selenium- and iodonium-initiated cyclisation of hydroxy-functionalised 1,4-dienes

• Philipp Röse,
• Steffen Emge,
• Jun-ichi Yoshida and
• Gerhard Hilt

Beilstein J. Org. Chem. 2015, 11, 174–183, doi:10.3762/bjoc.11.18

• in electrochemical reactions using selenium cations. Several methods applying electrochemically generated selenium cations with alkenes or alkynes including seleno-etherification and lactonisation, epoxidation and oxoselenylation sequences have been reported in the last decades [20][21][22][23][24

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

• - and stereoisomeric aminocyclitol derivatives remains in demand. One of the optimal routes involves the stereoselective ring opening of epoxides by different nucleophiles in the presence of a variety of activators [15][16][17][18][19]. In this context, epoxidation of cyclic allylic amines and

• aminoglycosides [7], and nucleosides containing 9H-purin-6-amine as a nucleobase portion. High levels of stereoselectivity have been observed in substrate-controlled diastereoselective epoxidation of cyclic alkenes with O- and N-allylic directing groups [20][21]. Several 3-substituted diastereomeric epoxides have

• starting epoxides Epoxides 3a,b (Scheme 1) were obtained by the addition of benzyl(methyl)amine or dibenzylamine to cyclopent-2-en-1-yl acetate (1) followed by epoxidation [28]. Epoxides 6a,b were synthesized from 3a,b through epoxide ring inversion using glacial acetic acid as the oxirane-cleaving agent

Indium-mediated allylation in carbohydrate synthesis: A short and efficient approach towards higher 2-acetamido-2-deoxy sugars

• Christopher Albler,
• Ralph Hollaus,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2014, 10, 2230–2234, doi:10.3762/bjoc.10.231

• azide reduction followed by final deacetylation using methanolic sodium methoxide furnishes the title compounds. Keywords: allylation; carbohydrates; epoxidation; indium; multivalent glycosystems; organocatalysis; Introduction The indium-mediated allylation of carbonyl compounds has proven to be a

• valuable tool for carbon chain elongation [1][2][3] in order to access rare, biologically active carbohydrates [4][5][6][7][8]. Herein we report the extension of this method towards the field of higher aminosugars by additionally applying a stereoselective epoxidation–azide opening strategy. The resulting

• the use of a chiral L-proline derived epoxidation catalyst. The introduction of nitrogen was achieved via a Tsuji–Trost-like azide opening of allylic epoxides. Although global deprotection proved to be cumbersome, we were able to develop a versatile reaction sequence to overcome this problem. The

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

• [26] and threo-10 [27] were prepared from divinylcarbinol using asymmetric epoxidation [28][29]. Diastereomeric mixtures of 3-O-benzyl 11, 3-O-silyl-protected 12 and fully unprotected triol 13 was prepared starting from 1,2-O-isopropylidene-D-glyceraldehyde using described procedures [30]. The

• compound 37 in good yield (77%). Synthesis of the similar substrate rac-42 having two conjugated double bonds is shown in Scheme 5. The synthesis started from the known acetate 38, which was obtained by acetylation of commercially available non-3-ene-1-ol [34]. Epoxidation of acetate 38 with MCPBA in

Expeditive synthesis of trithiotriazine-cored glycoclusters and inhibition of Pseudomonas aeruginosa biofilm formation

• Meriem Smadhi,
• Sophie de Bentzmann,
• Anne Imberty,
• Marc Gingras,
• Raoudha Abderrahim and
• Peter G. Goekjian

Beilstein J. Org. Chem. 2014, 10, 1981–1990, doi:10.3762/bjoc.10.206

• carbohydrate units proved to be problematic, as a result of the instability of the triazine system under either forcing or mild Zemplén deprotection conditions. The tert-butyldimethylsilyl-protected galactopyranosyl azide 5 was therefore prepared via the epoxidation of silylated D-galactal with

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• chiral auxiliary through ozonolysis followed by protection of the side chain as TBDPS ether afforded cyclopentanone 155. Saegusa–Ito oxidation followed by epoxidation of the formed enone gave 156 as the major isomer (dr 9:1). Regioselective reductive opening of the epoxide with Na[PhSeB(OEt)3] produced

Selective allylic hydroxylation of acyclic terpenoids by CYP154E1 from Thermobifida fusca YX

• Anna M. Bogazkaya,
• Clemens J. von Bühler,
• Sebastian Kriening,
• Alexandrine Busch,
• Alexander Seifert,
• Jürgen Pleiss,
• Sabine Laschat and
• Vlada B. Urlacher

Beilstein J. Org. Chem. 2014, 10, 1347–1353, doi:10.3762/bjoc.10.137

• catalyse either the allylic hydroxylation of alkenes or the epoxidation of the corresponding C=C double bond or produce a mixture of the respective allylic alcohols and epoxides. Chemo- and regioselectivity of such reactions depend on the structure of the substrate and P450 used [16]. Different P450

• mutants for the formation of C7-hydroxylated compound 11 as the main product. Variant V286L produced 44% of 7-hydroxygeranylactone (11) as well as the compounds 13 (18%) and 15 (35%). Substrate epoxidation leading to the epoxide 17 was much slower compared to the wild type: this product accounted to less

Heronapyrrole D: A case of co-inspiration of natural product biosynthesis, total synthesis and biodiscovery

• Jens Schmidt,
• Zeinab Khalil,
• Robert J. Capon and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2014, 10, 1228–1232, doi:10.3762/bjoc.10.121

• effect an epoxidation of 8. Application of substoichiometric amounts of oxidant (Oxone®) delivered the isomeric mono-epoxides 9 and 10 as the main constituents, along with minor amounts of the bis-epoxide 11. Of note, on work-up 9 was observed to undergo partial cyclization to the desired tetrahydrofuran

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

• will also be useful for the synthesis of other natural products containing this amino acid. Several synthetic approaches towards (2S,3S)-3-hydroxyleucine have been established utilizing for instance diastereoselective aldol reactions [26][27][28], Sharpless epoxidation [29], asymmetric hydrogenation

Synthesis of (2S,3R)-3-amino-2-hydroxydecanoic acid and its enantiomer: a non-proteinogenic amino acid segment of the linear pentapeptide microginin

• Rajendra S. Rohokale and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2014, 10, 667–671, doi:10.3762/bjoc.10.59

• -groups to olefinic acid by either asymmetric epoxidation, dihydroxylation or aminohydroxylation [10][11][12][13][14][15], (ii) the asymmetric synthesis of β-lactams by a Staudinger reaction between ketene and imine to give the corresponding amino acids [16], and (iii) the Lewis acid catalyzed

Intermediates in monensin biosynthesis: A late step in biosynthesis of the polyether ionophore monensin is crucial for the integrity of cation binding

• Wolfgang Hüttel,
• Jonathan B. Spencer and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 361–368, doi:10.3762/bjoc.10.34

• initially-formed (E,E,E)-triene undergoes stereospecific epoxidation to a tri-epoxide and subsequent ring-opening and cyclisation to generate the polyether rings. This model has been confirmed and extended (Scheme 1) by the results of more recent work in which specific genes have been disrupted or deleted

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

• in the formation of a bridged tetracycle after initial Heck coupling followed by carbo-palladation and subsequent β-hydride elimination [69][70][71]. Double bond regioisomers (between C7 & C8 or C13 & C14) were obtained. Oxidation with DDQ yielded the 1,6-unsaturated ketone 72. Selective epoxidation

• ). Deoxygenation with concomitant isomerization of the double bond according to Gevorgyan [100] was followed by epoxidation to provide barekoxide (106). Acid-catalyzed isomerization finally yielded barekol (107). Davies and coworkers [101][102][103] used the formal [4 + 3]-cycloaddition approach to access the

• ] applied the DVCPR in their total synthesis of gelsemine (146, see Scheme 20 and Scheme 21). Starting from bicycle 160 [140] epoxidation using mCPBA furnished epoxide 161 [141][142], which could be converted into vinylcyclopropanecarbaldehyde 162 upon rearrangement. Olefination using HWE-reagent 163

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

The difluoromethylene (CF₂) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF₂ groups

• Yi Wang,
• Ricardo Callejo,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2014, 10, 18–25, doi:10.3762/bjoc.10.4

• ketone 14 was treated with DAST. Conversion to the CF2 group occurred in modest (45%) yield. Generally aliphatic ketones are less efficiently converted to CF2 groups with DAST in comparison to propargylic ketones. Progression of the resultant CF2 containing olefin 15 by epoxidation, chain extension and

N,N'-(Hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide): Synthesis via cyclodextrin mediated N-alkylation in aqueous solution and further Prilezhaev epoxidation

• Julian Fischer,
• Simon Millan and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2834–2840, doi:10.3762/bjoc.9.318

• concentrations [10][11][12]. An alternative route is a two-step reaction via N-allylation and further Prilezhaev epoxidation with peroxides [13][14][15]. The solubility of hydrophobic reactants in water can be increased significantly by cyclodextrins (CD) and thereby the use of organic solvents can be reduced

• -methylbenzenesulfonamide) (3), as precursor for the subsequent N-alkylation and further Prilezhaev epoxidation, was synthesized easily from p-toluenesulfonyl chloride (1) and hexamethylenediamine (2) [23]. The resulting crystalline sulfonamide was first described in 1927 prepared from 1,6-dibromohexane and p

• moieties to the hydroxy functions is likely [2]). Synthesis of sulfonamide 3, N-alkylation of 3 in organic solution and of CD-complex (3β) in aqueous phase to obtain 5 and the subsequent epoxidation with m-chloroperbenzoic acid (mCPBA) to yield product 6. Cyclization of L-(+)-lysine monohydrochloride to

Stereoselectively fluorinated N-heterocycles: a brief survey

• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2013, 9, 2696–2708, doi:10.3762/bjoc.9.306

• ]-Wittig rearrangement, a diastereoselective epoxidation, and a microwave assisted transannular epoxide opening reaction. It is also noteworthy that the starting material 55 contains an extraneous fluorine atom which is deleted during the synthetic sequence; this approach takes advantage of the often low

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• conjugate addition [93], and a recent synthesis of lucentamycin A was achieved using this strategy [94]. Epoxidation of A leads to a highly functional intermediate C, which has been used in the synthesis of manzacidin B [95]. Among the plethora of olefination reactions, the Wittig [96][97] and Horner