The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• by nucleophiles. As is the case for the nucleophilic opening of epoxides, the regiochemistry of this process is often controlled very effectively by the combined steric and electronic effects of the substituents attached to the ring, with a spectrum of SN1 and SN2-like reactivity possible. Several

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• isomeric halofluorination products can be explained by the preferred formation of the halonium ions T6a–c, respectively, since the halogen cation attacks the C=C bond of the imide 19 from the less hindered side, followed by rearrangement into the intermediates (rac)-T7a–c, respectively. For epoxides and

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: theoretical evidence for an asynchronous concerted pathway

• Esra Demir,
• Ozlem Sari,
• Yasin Çetinkaya,
• Ufuk Atmaca,
• Safiye Sağ Erdem and
• Murat Çelik

Beilstein J. Org. Chem. 2020, 16, 1805–1819, doi:10.3762/bjoc.16.148

• Technology, Oltu Vocational School, Atatürk University, 25400 Oltu, Erzurum, Turkey Department of Chemistry, Faculty of Arts and Sciences, Marmara University, Goztepe Campus, 34722 Istanbul, Turkey 10.3762/bjoc.16.148 Abstract The one-pot reaction of chlorosulfonyl isocyanate (CSI) with epoxides having

• multicomponent reaction of rare-earth metal amides [28], the reaction of CO2 with propargylamines or aziridines [29][30] and the cycloaddition reaction of epoxides with isocyanates [31][32]. On the other hand, for the synthesis of five-membered cyclic carbonates, the cycloaddition of CO2 to epoxides, the

• reaction with the metal complexes or catalysts, and the reaction of a diol with toxic phosgene are the most common processes [16][17][33][34][35][36]. CSI, a highly reactive and versatile isocyanate, reacts with epoxides to give five-membered cyclic carbonates and oxazolidinones [37][38][39]. In 1984

The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• ester [9], which is cleaved in the second step, upon solvolysis, forming the final product (Scheme 1). Bromotrimethylsilane (BTMS) is the main reagent in this reaction and is also known for its ability to cleave lactones, epoxides, acetals, and ethers [10]. BTMS also acted as a brominating agent and

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• , cyclopentanone, and three carbon ring-expanded 1,3-diones from vinyl spiro epoxides [14]. The reaction is initiated by the addition of a thiyl radical to the vinyl epoxide 24, followed by the epoxide fragmentation to the alkoxy radical 25. Then, the β-cleavage to form the carbon-centered radical 26, the final

• expansion of vinyl spiro epoxides. Disulfide-catalyzed aerobic oxidation of diarylacetylene. Disulfide-catalyzed aerobic photooxidative cleavage of olefins. Disulfide-catalyzed aerobic oxidation of 1,3-dicarbonyl compounds. Proposed mechanism of the disulfide-catalyzed aerobic oxidation of 1,3-dicarbonyl

Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles

• Lívia Dikošová,
• Júlia Laceková,
• Ondrej Záborský and
• Róbert Fischer

Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112

• isoxazolidines by means of dihydroxylation [9][10] and epoxidation [11][12] reactions. Regarding the stereochemistry, almost all of the realized additions proceed with an excellent trans stereoselectivity relative to the substituent at C-3, giving isoxazolidine-4,5-diols and isoxazolidinyl epoxides with a C-3/4

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

• Svetlana A. Kuznetsova,
• Alexander S. Gak,
• Yulia V. Nelyubina,
• Vladimir A. Larionov,
• Han Li,
• Michael North,
• Vladimir P. Zhereb,
• Alexander F. Smol'yakov,
• Artem O. Dmitrienko,
• Michael G. Medvedev,
• Igor S. Gerasimov,
• Ashot S. Saghyan and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2020, 16, 1124–1134, doi:10.3762/bjoc.16.99

• , including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate

• catalyst for the Brønsted acid-catalyzed ring opening reactions of epoxides with alcohols and water, with the latter reaction occurring in a three-phase medium. In addition, a Diels–Alder reaction was promoted by F-1 in heptane. Results and Discussion Mixing together aqueous solutions of two equivalents of

• opening. Other epoxides were also studied as substrates for the three-phase ring-opening with water (Table 2, runs 6–9). Propylene oxide and butylene oxide were good substrates for the reaction (Table 2, runs 6 and 7), but hex-1-ene oxide was almost unreactive (Table 2, runs 8 and 9), indicating that some

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• photoinduced cycloaddition of carbon dioxide with epoxides [56]. The synthesis of a 3D supramolecular framework, [{Mn(TCPP)0.5(H2O)}·2H2O]n, where Mn(TCPP) is Mn(II) meso-tetrakis(4-carboxyphenyl)porphyrin, was derived from MnCl2·6H2O and TCPP. The cycloaddition product, a cyclic carbonate, was obtained from

• different epoxides, whose conversion was proportional to the substrate size, using MOF1 and tetra-n-butylammonium bromide (TBAB) as photocatalyst and co-catalyst, respectively (Scheme 25). A successful gram-scale protocol was developed opening up perspectives for using these materials in CO2 reuse

• acids using Pt or Pd porphyrins. Photocatalytic reduction of various nitroaromatics using a Ni-MOF. Photoinduced cycloadditions of CO2 with epoxides by MOF1. TPP-photocatalyzed generation of 1O2 and its application in organic synthesis. Adapted from [67][68][69]. Pericyclic reactions involving singlet

Synthesis of disparlure and monachalure enantiomers from 2,3-butanediacetals

• Adam Drop,
• Hubert Wojtasek and
• Bożena Frąckowiak-Wojtasek

Beilstein J. Org. Chem. 2020, 16, 616–620, doi:10.3762/bjoc.16.57

• unsymmetrically substituted cis-epoxides. The procedure was applied for the preparation of both enantiomers of disparlure and monachalure, the components of the sex pheromones of the gypsy moth (Lymantria dispar) and the nun moth (Lymantria monacha) using methyl (2S,3R,5R,6R)-3-ethylsulfanylcarbonyl-5,6-dimethoxy

• -5,6-dimethyl-1,4-dioxane-2-carboxylate as the starting material. Keywords: 2,3-butanediacetal; cis-epoxide; (−)-disparlure; (+)-disparlure; (−)-monachalure; (+)-monachalure; Introduction Compounds containing chiral epoxides display a wide range of biological activities and a number of them are

• recently developed by Mori and co-workers [6][7]. (2E)-trans-4,5-Epoxy-2-decenal is present in mammalian blood and may be used by predators to track their prey [8][9]. A classical example of cis-epoxides with semiochemical activity is the chemical communication system of the gypsy moth (Lymantria dispar

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• -functionalized silica 46 was added to the mixture, and this was heated to reflux to generate the catalyst 48. Several organic halides or epoxides, nonactivated alkynes, and sodium azide were reacted in an aqueous medium to provide triazoles or β-hydroxytriazoles using 1.0 mol % catalyst loading at 25 °C

• reflux conditions for one day. The resulting powder was filtered off, washed with methanol, and dried. Finally, excess copper was removed by the Soxhlet extraction method (Scheme 9). The 1,3-dipolar reaction of organic alkynes, organic bromides (or aryldiazonium salts or epoxides), and sodium azide

• , washed with THF and dichloromethane, and dried. Different organic halides (benzyl bromides, benzyl chloride, allyl bromide, aliphatic epoxides, and aromatic epoxides) were treated with sodium azide and phenylacetylene in the presence of a catalytic amount of the copper catalyst 121 in water at 70 °C

KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

• Qiao Lin,
• Shiling Zhang and
• Bin Li

Beilstein J. Org. Chem. 2020, 16, 492–501, doi:10.3762/bjoc.16.44

• epoxides as substrates via alternative synthetic procedures [6]. However, under acidic conditions, oxazolines transform into β-substituted carboxamides through nucleophilic ring opening with SN2 attack at the C5 position of the ring [7][8]. Recently, Guo’s group developed an efficient method for the

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• that inhibits cationic polymerization of epoxides [5]. Though conjugate acids are formed according to the routes shown in Scheme 6, cationic photopolymerization only succeeded with aziridines [5]. The different reaction mechanism occurring with such monomers explains these different observations [92

• photoproducts were formed and cationic photopolymerization even of epoxides succeeded with good conversions vide infra. Additional absorbers fitting in this scheme comprise at the meso-position alternative substituents such as Phenyl or Chlorine (see Table 1 for comparison). Surprisingly, this reaction has not

• the sensitizer 48 and the iodonium cation 88 (used as PF6−-salt) to photopolymerize aziridines. The photoproducts formed according to Scheme 6 do not significantly inhibit chain growth of such monomers while no polymerization occurred with epoxides. Again, the strong nucleophilic properties of the

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• towards asymmetric electroepoxidation of olefins 71 in a biphasic CH2Cl2/aqueous NaCl system (Scheme 28). The constant current epoxidation of 71 in an undivided cell resulted in chiral epoxides 73 in good yields and moderate enantioselectivities [66]. In 2008, Onomura and co-workers described the

• oxidant required for this process was initially generated through anodic oxidation of aqueous Na2CO3 in an undivided cell under constant current electrolysis. A catalytic amount of chiral iminium salt 103 and olefinic substrate 71' were added to the same reaction mixture, and chiral epoxides 73' were

• potentiostatic electrolysis, styrene derivatives 143 could be transformed into their asymmetric epoxides 144 via direct electrochemical regeneration of FADH2. The authors claimed that this method is superior with respect to substitution of the complex native regeneration cycle, which consists of three enzymes

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• developed independently by the groups of Buchwald [111] and Wang [112] (Scheme 54). Under similar mild conditions using Togni's reagent II, the desired allyl–CF3 products were obtained and the methods well tolerated a variety of functional groups (e.g., esters, epoxides, amides, alcohols, or aldehydes

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• nanoreactor because there is an acceleration of the dimerization by two orders of magnitude and the turnover of the catalyst was demonstrated. The synthesis of cyclic carbonates from epoxides and CO2 is an efficient method for CO2 fixation. The development of an effective chiral catalyst for the efficient

• kinetic resolution of epoxides with CO2 remains a big challenge. Recently, Ema and co-workers described a chiral binaphthyl strapped Zn(II) porphyrin with triazolium halide units as a bifunctional catalyst for the kinetic resolution of epoxides with CO2 [63]. The condensation of click-reaction-derived

• binaphthyl system and the Lewis acidic metal center facilitated the enantioselective synthesis of cyclic carbonates from epoxides. Various catalyst was screened by changing the linker length (n = 4 to 8) and nucleophilic counter anion (X = I, Cl, Br), and 16c was found to be the best catalyst for the

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• development of total synthesis strategies. Structurally, it has nine chiral centers, three successive epoxides and a butenolide. Since the pioneering works of Berchtold, Tahara and their co-workers [45][63][64][65], several racemic and/or asymmetric total syntheses of triptolide and its relatives have been

• -catalyzed lactonization, and iii) construction of the epoxides by a newly developed methodology. The synthesis commenced from the alkylation of tetralone 22 with 3-(2-iodoethyl)dihydrofuran-2(3H)-one (23) to give diastereomeric lactones that subsequently reacted with dimethylamine to afford a 1:1 mixture of

• conversion of 89 to vinyl triflate 90, followed by reduction and palladium-catalyzed carbonylation–lactone formation to give key intermediate 8 [75][76][77]. After that, the three successive epoxides were installed by known procedures with some modification. The highlights were the introduction of the second

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• aromatic analytes afford strongly induced circular dichroism (ICD) signals in the near-UV and visible regions [18]. Endo-functionalized molecular tubes, first reported by the Glass group [19], were used by the Jiang group for molecular recognition and chiroptical sensing of epoxides in water. The absolute

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• especially useful when the crystalline complex formation with the guest is undesirable. The aggregation properties, by the ready-to-associate secondary rim, are considerably affected by these substituents. One of the most important reactions of CDs occurs with oxiranes (epoxides) under basic conditions to

• factors, but also by the lack of uniformity and the site-by-site variability of prepared CDPs, which have hampered the extensive CDP use. Mechanochemistry has proven to be a useful green tool in the hands of synthetic chemists [25][26][27][28]. The reaction of epoxides with cyclodextrins under green and

• optimisation. Results and Discussion Reaction of epoxides with CDs The reactions of oxiranes, particularly propylene oxide, with CDs in solution have been extensively studied and the products are synthesised on the ton-scale by various companies [6][30][31][32]. The reaction is based on the activation of

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• chloride to give the corresponding β-thioaryl ketone 4 [10]. Reacting 2 with epoxides results in the formation of the 1-(β-hydroxy)cyclopropyl aryl sulfides 5 [10] while reaction with formaldehydes [11] or aldehydes [12] affords 1-(arylthio)cyclopropylcarbinyl alcohols 6. Treating 6 with Burgess reagent or

Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection

• Shahien Shahsavari,
• Dhananjani N. A. M. Eriyagama,
• Bhaskar Halami,
• Vagarshak Begoyan,
• Marina Tanasova,
• Jinsen Chen and
• Shiyue Fang

Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108

• protected with the 2-cyanoethyl group. These protecting groups and the linker have to be cleaved under strongly basic and nucleophilic conditions. As a result, many sensitive groups including acetal, hemiacetal, vinyl ethers, enol ethers, aldehydes, esters, activated esters, thioesters, aziridines, epoxides

Easy, efficient and versatile one-pot synthesis of Janus-type-substituted fullerenols

• Marius Kunkel and
• Sebastian Polarz

Beilstein J. Org. Chem. 2019, 15, 901–905, doi:10.3762/bjoc.15.87

• the characterization of Janus-type fullerenol amphiphiles more than one method is needed to perfectly identify the compounds. Polyhydroxylation reaction of the fullerene can lead to a mixture of several oxygen moieties like hydroxy groups, diols, ketones, hemiketals, epoxides and ethers. The general

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• epoxides, for which the maximum theoretical yield of the reaction is 50%. Here, however, the yield of the sn-1,3-protected monoacylglycerol was high, and consequently we expected the enantiomeric excess of the product to be low. This, assumption was confirmed by analysis of the sample by high-performance

Stereochemical investigations on the biosynthesis of achiral (Z)-γ-bisabolene in Cryptosporangium arvum

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 789–794, doi:10.3762/bjoc.15.75

• analysis of the preceeding epoxides, Figure S5, Supporting Information File 1) were purified by preparative HPLC on a chiral stationary phase to >99% ee for both samples (Figure S6, Supporting Information File 1), before converting them into the NPPs. For comparison, also racemic NPP was synthesised by a

• , labelling experiments for NMR assignment, synthetic procedures for the NPPs, Mosher ester analysis of epoxides, and chiral GC analysis of nerolidols. Supporting Information File 260: Experimental part. Acknowledgements This work was funded by the Deutsche Forschungsgemeinschaft (DI1536/7-1). We thank

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• (cyclohexene carbonate)s was carried out by the β-diiminate (BDI) zinc-catalyzed block copolymerization of functionalized epoxides and CO2 with a norbornenyl-containing initiator (Scheme 5) [68]. The subsequent “grafting through” by ROMP of norbornene resulted in the synthesis of multiblock copolymer brushes