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

• ions generated by the reaction of electrogenerated Br+ and I+ ions stabilized by dimethyl sulfoxide (DMSO) reacted with sodium hydroxide and sodium methoxide to give the corresponding halohydrins and epoxides, respectively, whereas the treatment with triethylamine gave α-halocarbonyl compounds

• . Keywords: DMSO; electrosynthesis; epoxides; halohydrins; halogen cations; Introduction Alkene difunctionalization through three-membered ring halonium ion intermediates [1] is an important transformation in organic synthesis. Usually the halonium ions such as bromonium or iodonium ions are generated by

• expanding the utility of the present method. The treatment of β-haloalkoxysulfonium ions 3-X with sodium hydroxide gave the corresponding halohydrins 5-X, while the treatment with sodium methoxide gave epoxides 6 (Scheme 1). Results and Discussion Reactions of β-bromoalkoxysulfonium ions generated from (Z

Anion effect controlling the selectivity in the zinc-catalysed copolymerisation of CO₂ and cyclohexene oxide

• Sait Elmas,
• Muhammad Afzal Subhani,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 42–49, doi:10.3762/bjoc.11.7

• with epoxides (Scheme 1) is a prime example of a particularly attractive transformation of CO2 [8][9] and is at the verge of commercialisation [8]. In this transformation, the low energy level of the CO2 molecule is overcome by reacting CO2 with an epoxide as energy-rich comonomer [10]. Homogeneous and

• of the transition metal cations (Co, Cr) often employed in Type II catalysts, albeit zinc catalysts have lower activity in the copolymerisation of CO2 and epoxides [16]. The use of catalysts of Types I and II in the copolymerisation of CO2 and epoxides leads commonly to fully alternating

• ]. To keep the catalyst loading during the synthesis of such polyols low, chain transfer between the growing polymer chain and free alcohol groups needs to be realised. In this study, we have addressed such immortal copolymerisation of CO2 and epoxides with zinc catalysts. In the Type I lead catalyst

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

• of 4.1% to 3.3%. In the recovered oil, reduced concentrations of 1.55% to 1.3%, and 2.1% to 1.75% were observed (see Table 1). Furthermore, all terpene epoxides (even those found in lower relative concentrations) were encapsulated in very low concentrations in the β-CD complexes in comparison with

• ) corresponds to a lower relative concentration of the degradation compound in the β-CD complex. Significant protection against oxidation at higher temperatures was observed in the case of alloaromadendrene and in unidentified sesquiterpenes. Their epoxides were encapsulated in β-CD in lower relative

• in β-CD as compared to some of the sesquiterpenes and especially with respect to sesquiterpene epoxides (some of them are reactive and possibly harmful compounds), which indicates the enhanced quality and stability of the O. basilicum L./β-CD complex. Experimental Materials The Ocimum basilicum L

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

• aminolysis of epoxides 6a,b afforded mainly C1 adducts 13a,b arising from trans-diaxal opening of the epoxide ring. Using a Lewis acid catalyst, epoxides 6a,b were transformed into diaminocyclopentanols 14a,b via an alternative pathway involving the formation of aziridinium intermediate 17. Keywords

• : diaminocyclopentanols; epoxides; regioselectivity; ring opening; stereoselectivity; Introduction In recent years mimicry of aminoglycosides [1][2][3][4][5][6][7] and nucleosides [8][9][10] has become an important field in pharmaceutical research. Regio- and stereochemical diversities within a sugar-like moiety in

• - 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

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

• temperatures and pressures to activate CO2 [2][3]. Efficient chemical incorporation of CO2 is limited to rather reactive substrates, like epoxides [4][5][6] and amines [7][8][9] to produce cyclic carbonates and carbamates, respectively, and even then, elevated reaction temperatures and/or complex catalyst

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

• obtained allylic epoxides were regio- and stereoselectively opened with trimethylsilyl azide under palladium catalysis. Finally, a suitable deprotection protocol, starting with acidic acetate cleavage and ozonolysis was established. Peracetylation of the products simplifies purification and subsequent

• (CHCO2Me)) generated allylic epoxides 4a–c, which in turn permitted the application of reliable palladium chemistry for the epoxide opening [27][28][29]. Thus, compounds 4a–c were regio- and stereoselectively opened with trimethylsilyl azide and Pd(PPh3)4 as a catalyst [30], furnishing syn-azido alcohols

• 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

Comparing kinetic profiles between bifunctional and binary type of Zn(salen)-based catalysts for organic carbonate formation

• Carmen Martín and
• Arjan W. Kleij

Beilstein J. Org. Chem. 2014, 10, 1817–1825, doi:10.3762/bjoc.10.191

• employed as active catalysts for the formation of cyclic carbonates from epoxides and CO2. A series of kinetic experiments was carried out to obtain information about the mechanism for this process catalyzed by these complexes and in particular about the order-dependence in catalyst. A comparative analysis

• stock for the synthesis of organic compounds being also of interest in an industrial context [1][2][3][4][5]. This inexpensive, abundant and nontoxic source of carbon has been extensively used to convert epoxides into their respective cyclic carbonates [6][7][8][9] (Scheme 1), that find useful

• investigation of the mechanism of the coupling between CO2 and epoxides catalyzed by Zn-based complexes containing salen ligands. A comparative kinetic analysis between the binary system Zn(salphen) 1/NBu4I and bifunctional, alkylated Zn(salpyr) complex 2 [salpyr = N,N′-bis[salicylidene]-3,4-pyridinediamine

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts

• Jong Yeob Jeon,
• Seong Chan Eo,
• Jobi Kodiyan Varghese and
• Bun Yeoul Lee

Beilstein J. Org. Chem. 2014, 10, 1787–1795, doi:10.3762/bjoc.10.187

• with epoxides [1][2][3][4][5][6]. The pioneering work for this copolymerization was introduced by Inoue in 1969 [7]. Eventually, a highly active and efficient catalyst was developed based on the concept of combining (salen)Co(III) units with quaternary ammonium salts in a molecule [8][9][10][11][12

• from the resin for use in our daily life. In this work, we demonstrate the complete incorporation of the third monomer of phthalic anhydride (PA) in CO2/PO copolymerizations using catalyst 1. Results and Discussion PO/PA copolymerizations Alternating copolymerizations of epoxides and cyclic anhydrides

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

• reagent precursors in a wide range of halogenation reactions. The rasta resin–triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form

• reactions, such as those illustrated in Scheme 2: (1) the conversion of alcohols 4 to alkyl halides 5 (the Appel reaction), (2) the conversion of aldehydes 6 to 1,1-dihaloalkanes 7, (3) halogenation of aziridines 8 to form 2-haloamines 9, (4) halogenation of epoxides 10 to form 1,2-dihaloalkanes 11, (5) and

• indicated that the reactions were complete, 3–4 hours, the reaction mixtures were filtered and the filtrates were concentrated to afford products that were essentially pure according to both 1H and13C NMR analysis. Reactions with epoxides bearing phenyl (Table 6, entries 1 and 2), benzyl (Table 6, entries 3

Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

• Melanie Rauschenberg,
• Eva-Corrina Fritz,
• Christian Schulz,
• Tobias Kaufmann and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2014, 10, 1354–1364, doi:10.3762/bjoc.10.138

• synthesized as described in Supporting Information File 1. The effective immobilization of the amine-terminated carbohydrate inks requires a surface functionalized with epoxides. Epoxides are stable under ambient conditions yet highly reactive towards amines at elevated temperatures and epoxide SAMs on

• morphology [47][48][49][50]. Therefore, the epoxide SAMs were prepared by the method of Julthongpiput et al. because well-defined monolayers of epoxides on glass and silicon substrates can be obtained by using (3-glycidoxypropyl)trimethoxysilane in toluene [42]. The successful surface modification was

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

• products, mainly epoxides but also allylic alcohols [19]. Later a CYP102A1 double mutant F87V/A328L was identified producing 80% allylic alcohols starting with geranylacetone [20]. These hydroxylated products are useful building blocks for the total syntheses of several natural compounds including

• . All three mutants V286L, V286A, and V286F showed strong preference for epoxides when starting with geraniol (1) and nerol (2), respectively. Mutant V286L was able to oxidise geraniol (1) to a mixture of 6,7-epoxygeraniol (5, 26%) and diepoxygeraniol 7 (74%) with 11% conversion, while nerol (2) was

Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• intramolecular nucleophilic substitution reactions e.g. epoxides from β-hydroxy phenyl selenides [9][10], N-benzoyl- and N-tosyl-1,3-oxazolidin-2-ones from β-hydroxyalkyl phenyl selenides [11], N-arenesulfonylazetidines from γ-(phenylseleno)alkyl arylsulfonamides [12], N-acylaziridines [13], 1,3-oxazolines

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

Metal and metal-free photocatalysts: mechanistic approach and application as photoinitiators of photopolymerization

• Jacques Lalevée,
• Sofia Telitel,
• Pu Xiao,
• Marc Lepeltier,
• Frédéric Dumur,
• Fabrice Morlet-Savary,
• Didier Gigmes and
• Jean-Pierre Fouassier

Beilstein J. Org. Chem. 2014, 10, 863–876, doi:10.3762/bjoc.10.83

• delivered, e.g., by household lamps and LED bulbs) can be used; this is a catalytic process without loss of efficiency with irradiation. Photopolymerization under sunlight becomes reachable. The production of the radical or cationic initiating species for the FRP of acrylates or the FRPCP of epoxides

• (JASCO FTIR 4100) at about 1630 cm−1 as in [15]. iv) The ring opening polymerization of epoxides: The photosensitive formulations were deposited (25 µm thick) on a BaF2 pellet under air. The evolution of the epoxy group content was continuously followed by real time FTIR spectroscopy (JASCO FTIR 4100) at

• ][52][53][54][55]) in formulations containing multifunctional synthetic epoxides, acrylates, monomers/oligomers or epoxide/acrylate blends (renewable raw or modified materials are usable to some extent) with lights extending from the UV to the red, using polychromatic or monochromatic light sources

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

• epoxides (see 304) were shown to undergo trans-cis isomerization followed by divinylepoxide rearrangement to give dihydrooxepine 305 at 125 °C. The necessary reaction temperature could be lowered using copper(II) catalysis, accelerating the reaction rate as well. The vinylepoxide–carbaldehyde rearrangement

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

• peroxides. In some cases, the reaction with 1,5-dienes 46a–d produces, along with 1,2-dioxanes 51 (desilylation products of the corresponding 1,2-dioxanes 48), 1,2-dioxolanes (52b,d) as a result of cyclization of the corresponding peroxysilyl epoxides 49. In these reactions, unsaturated triethylsilyl

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

• are relatively comparable to a mixture of BADGE with 8, whereby the observed differences can be caused by different reactivity of the oxirane moieties or unequal solubility of the respective diepoxide with 8. By means of IR spectroscopy, ring opening polymerization of epoxides with amines can be

Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

• Julian Fischer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2803–2811, doi:10.3762/bjoc.9.315

• cyclization [22]. Native amino acids are not suitable for fast reaction with epoxides at low temperatures, presumably due to protonation of their amine groups that results in a reduction of their nucleophilicity [23]. However, by means of the described α-amino-ε-caprolactam (7), we expect to increase the

• reactivity of the primary amine group towards epoxides due to the formation of activating hydrogen bonds. The subsequent epoxide–amine polyaddition was carried out with glycerol diglycidyl ether (8), which was directly used as a mixture of the structural isomers 8a and 8b. To facilitate the following

Flow microreactor synthesis in organo-fluorine chemistry

• Hideki Amii,
• Aiichiro Nagaki and
• Jun-ichi Yoshida

Beilstein J. Org. Chem. 2013, 9, 2793–2802, doi:10.3762/bjoc.9.314

• selectively can be enhanced dramatically by the use of continuous flow microreactor devices. Daikin Industries, Ltd. developed the flow microreactor synthesis of fluorinated epoxides. In the first step (radical addition of perfluoroalkyl iodides to unsaturated alcohols), there is a problem concerning the

• violent exothermic reaction induced by decomposition of AIBN [50]. Furthermore, in the second step (intramolecular nucleophilic substitution of β-iodoalcohols to afford epoxides), efficient mixing technique is required for biphasic aqueous–organic systems. To resolve all the troublesome issues, flow

• microreactor provided improved reaction control over traditional batch reactors; high-yield synthesis of fluorinated epoxides was achieved (Scheme 3). Kitazume et al. demonstrated the benefit of flow microreactors for a highly stereoselective synthesis of difluoromethylated alkenes [51]. They succeeded in

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

• aziridines. Aziridines (1, Figure 1) are generally very stable, in marked contrast with their oxygenated counterparts, the epoxides. However, if one or two fluorine atoms are attached to the aziridine backbone, the resulting molecule is much more susceptible to hydrolysis. De Kimpe and co-workers have

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• to start with diastereomerically pure theaspirane (trans-1) that was obtained by chromatographic separation of the commercial diastereomeric mixture of cis- and trans-theaspirane (1). As depicted in Scheme 4, trans-theaspirane (trans-1) was converted to the corresponding epoxides 4a and 4b following

• reaction mixtures containing minor amounts of the target allyl alcohol 22. In an alternative protocol, we used Yamamoto´s conditions [47] for the isomerization of epoxides (TMP, n-BuLi, Et2AlCl) and obtained allyl alcohol 22 in excellent 93% yield. The conversion of allyl alcohol 22 to vitispirane (23) has

• detected similar oxidation products with PSA and rationalize their formation by an initial epoxidation of the endocyclic double bond to give the allyl epoxide 25, which might then be hydrolyzed to two diastereomeric alcohols 26a and 26b. The latter reaction is known for similar allyl epoxides under

Synthesis of enantiomerically pure N-(2,3-dihydroxypropyl)arylamides via oxidative esterification

• Akula Raghunadh,
• Satish S More,
• T. Krishna Chaitanya,
• Yadla Sateesh Kumar,
• Suresh Babu Meruva,
• L. Vaikunta Rao and
• U. K. Syam Kumar

Beilstein J. Org. Chem. 2013, 9, 2129–2136, doi:10.3762/bjoc.9.250

• the reaction conditions are given in Table 2. All the starting epoxides required for this transformation were prepared by using the reported procedures. After the synthesis of optically pure 3-(1,3-dioxoisoindolin-2-yl)-2-hydroxypropylarylate derivatives (5a–h), the removal of the phthalimide group

Gold(I)-catalyzed formation of furans from γ-acyloxyalkynyl ketones

• Marie Hoffmann,
• Solène Miaskiewicz,
• Jean-Marc Weibel,
• Patrick Pale and
• Aurélien Blanc

Beilstein J. Org. Chem. 2013, 9, 1774–1780, doi:10.3762/bjoc.9.206

• gold(III) has been reported starting from terminal alkenes, glyoxal derivatives and secondary amines [49]. In this emerging research area, we have been focusing our effort on the development of furan motifs from alkynyl epoxides [21][22][50][51] and new precursors, i.e. γ-acyloxyalkynyl ketones. The

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• Ping-An Wang Department of Medicinal Chemistry, School of Pharmacy, Fourth Military Medical University, Changle Xilu 17, Xi-An, 710032, P. R. China 10.3762/bjoc.9.192 Abstract Enantioselective desymmetrization of meso-aziridines and meso-epoxides with various nucleophiles by organocatalysis has

• emerged as a cutting-edge approach in recent years. This review summarizes the origin and recent developments of enantioselective desymmetrization of meso-aziridines and meso-epoxides in the presence of organocatalysts. Keywords: aziridine; desymmetrization; enantioselectivity; epoxide; organocatalysis

• compounds from readily available achiral substrates. The past decade witnessed the renaissance and the golden age of organocatalyzed reactions [7][8][9]. Aziridines and epoxides are quite reactive due to the large tension of their three-membered ring system. The enantioselective ring-opening of aziridines

Computational study of the rate constants and free energies of intramolecular radical addition to substituted anilines

• Andreas Gansäuer,
• Meriam Seddiqzai,
• Tobias Dahmen,
• Rebecca Sure and
• Stefan Grimme

Beilstein J. Org. Chem. 2013, 9, 1620–1629, doi:10.3762/bjoc.9.185

• -based transformations are amongst the most attractive methods for the use in catalytic cycles due to the ease of radical generation, high functional group tolerance, and selectivity in C–C bond formation [3][4][5]. Recently, we have reported a novel catalytic reaction, a radical arylation of epoxides [6

• for the addition of 1 readily explains the excellent synthetic results with epoxides derived from aryl substituted anilines in the radical arylation of epoxides. The reaction of 3 is too slow to be useful in typical radical chain reactions. However, reactions under our catalytic reaction conditions [6

• -substitution. Addition reactions leading to indanes or dihydrobenzofurans are too slow to be useful. Optimized structure of the transition state of the radical addition of 1 (left: spin density plot and atomic spin-density populations; right: SOMO). Experimental results for the radical arylation of epoxides. 5