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

• [19]. The 7-membered B ring in 21 had no influence on the stereochemical outcome of the reaction with MCPBA which resulted in the formation of the α-epoxide 22. The same was true for the electrophilic addition of Br+ to the olefinic unit of 21. It produced the trans-diaxial bromohydrine 23 that was

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• (+/−)-perhydrohistrionicotoxin. Addition of Gilman’s reagents to α,β-epoxy oximes 53. Addition of Gilman’s reagents to α-chlorooximes. Reaction of silyl nitronate 58 with organolithium reagents via nitrosoalkene NSA12. Reaction of β-ketoxime sulfones 61 and 63 with lithium acetylides. Electrophilic addition of nitrosoalkenes

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• applications of alkynyl selenides are electrophilic addition reactions, many of them modulated by transition-metal catalysts [11]. Some examples are: hydroboration which results in a vinylborane selenide used in Pd-catalyzed Suzuki cross-coupling reactions [12], the addition to tributyltin hydride in the

• (Table 4, entry 10). The subsequent electrophilic addition of I2 to selenide 5q afforded 3-iodo-2-(n-octylselanyl)benzofuran (10) in excellent yield (93% isolated yield, Scheme 4). Finally, we compared our method with syntheses reported in the literature that mainly rely on commercially available

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• ) electrophilic addition of I2 to the alkyne moiety of this intermediate produces the iodonium intermediate B, (iii) isomerization of iodonium B gives intermediate C and (iv) a sequential intramolecular cyclization and HI elimination of C finally affords thiazolidines 27 [88]. Seeking for a greener approach

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

• Shuai Qiu,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222

• activated alkenes, including nitroalkenes, 4-oxo-4-arylbutenones, 4-oxo-4-arylbutenoates and methyleneindolinones [10]. This work elucidated the feasibility of the electrophilic addition to the C2 position of 5H-thiazol-4-ones. More importantly, it provided a direct and convenient approach to synthesize

Mechanism, kinetics and selectivity of selenocyclization of 5-alkenylhydantoins: an experimental and computational study

• Biljana M. Šmit,
• Radoslav Z. Pavlović,
• Dejan A. Milenković and
• Zoran S. Marković

Beilstein J. Org. Chem. 2015, 11, 1865–1875, doi:10.3762/bjoc.11.200

• , State University of Novi Pazar, Vuka Karadžića bb, 36300 Novi Pazar, Serbia 10.3762/bjoc.11.200 Abstract The mechanism and selectivity of a bicyclic hydantoin formation by selenium-induced cyclization are investigated. The proposed mechanism involves the intermediates formed by an electrophilic

• addition of the selenium reagent on a double bond of the starting 5-alkenylhydantoin prior the cyclization. These intermediates are readily converted into the more stable cyclic seleniranium cations. A key step of the mechanism is an intramolecular cyclization which is realized through an anti-attack of

• to the formation of fused bicyclic hydantoins, a computational (DFT) study was carried out. The mechanism of the reaction of 5-alkenylhydantoins with phenylselenyl chloride was examined using the reaction with model substrate 1. The proposed five-step mechanism, starting with an electrophilic

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• oxidation in the presence of various mediators leads to electrophilic addition to the double bond, oxidation at the allylic position, oxidation of the hydroxy group, or functionalization of the side chain. Recent studies have proven that direct electrochemical oxidation of cholesterol is also possible and

• , which were anodically oxidized to chlorine. The electrophilic addition of chlorine to the double bond of the investigated compounds cholesteryl acetate (1a), cholesteryl benzoate (1b), 3β-chloro-5-cholestene (1c), and 5-cholestene (1d), gave the corresponding 5α,6β-dichloro steroids in good yields (70

Aza-Diels–Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

• Amitabh Jha,
• Ting-Yi Chou,
• Zainab ALJaroudi,
• Bobby D. Ellis and
• T. Stanley Cameron

Beilstein J. Org. Chem. 2014, 10, 848–857, doi:10.3762/bjoc.10.81

• the N-aryl group undergo intramolecular electrophilic addition to the alkene yielding isoindolo[2,1-a]quinolines under acidic conditions [18]. Isoindolo[2,1-a]quinolone cores have also been prepared via an aldol-type intramolecular cyclization reaction of N-(2-acetylaryl)phthalimide under anhydrous

• imino-Diels–Alder reaction with N-acyliminium cations as dienes. The most important aspect of this investigation is the dissimilar outcome of the reactions of N-(2-substituted-aryl)-3-hydroxyisoindolinones with N-vinylpyrrolidone under identical conditions which resulted in the electrophilic addition of

Group-assisted purification (GAP) chemistry for the synthesis of Velcade via asymmetric borylation of N-phosphinylimines

• Jian-bo Xie,
• Jian Luo,
• Timothy R. Winn,
• David B. Cordes and
• Guigen Li

Beilstein J. Org. Chem. 2014, 10, 746–751, doi:10.3762/bjoc.10.69

• further purification. B2Pin2 and ICyCuOt-Bu were utilized as the electrophilic addition reagent and catalyst, respectively, for the borylation reaction as previously reported [16][28]. Unlike the previous system, in which benzene was employed as the solvent, we used the much less toxic solvent toluene to

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

• Yuta Nishina,
• Bunsho Ohtani and
• Kotaro Kikushima

Beilstein J. Org. Chem. 2013, 9, 1663–1667, doi:10.3762/bjoc.9.190

• hydrocarbons proceeds through radical abstraction of hydrogen atoms and trapping with bromide, whereas the bromination reactions of aromatic and unsaturated hydrocarbons are induced by electrophilic addition of bromine and/or a cationic bromide. Combinations of N-bromosuccinimide (NBS) with

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• character (NICS(1)). However, while the electrophilic addition to the exocyclic double bond of 47a yields the cyclic conjugated 6π system in 48a, the analogous electrophilic addition to 47c yields the nonaromatic amidinium ion 48c. The high nucleophilicity of 45a, which is mirrored by the high proton

Dioxane dibromide mediated bromination of substituted coumarins under solvent-free conditions

• Subrata Kumar Chaudhuri,
• Sanchita Roy and
• Sanjay Bhar

Beilstein J. Org. Chem. 2012, 8, 323–329, doi:10.3762/bjoc.8.35

• vicinal anti-dibromides through highly diastereoselective electrophilic addition of bromine across various electron-deficient and electron-rich double bonds [14] using DD under solvent-free conditions. Two compounds of the present investigation (2a and 2g in Table 1, see below) were synthesized during the

• detailed results are summarized in Table 1. When an unsubstituted coumarin (1a) was subjected to bromination with DD under solvent-free conditions, vicinally anti-dibromide 2a was obtained exclusively through electrophilic addition of bromine across the electron-deficient double bond of the conjugated δ

• conclusively proved the presence of two bromine atoms in the product, which were due to electrophilic addition of bromine across the olefinic linkage without any vinylic substitution. 4-Methyl-7-(allyloxy)coumarin (1h) (Table 1, entry 9) underwent addition of bromine across the isolated double bond as well as

A concise synthesis of 3-(1-alkenyl)isoindolin-1-ones and 5-(1-alkenyl)pyrrol-2-ones by the intermolecular coupling reactions of N-acyliminium ions with unactivated olefins

• Nianhong Lu,
• Lihong Wang,
• Zhanshan Li and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 192–200, doi:10.3762/bjoc.8.21

• ]. We have long been interested in the reactions of N-acyliminium ions produced easily by the Brønsted acid and Lewis acid catalyzed dehydroxylation of α-hydroxyamides [12][13][14]. The high electrophilicity of these species is very suitable for electrophilic addition to carbon–carbon multiple bonds

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• cyclization of the alkynylindole 251 using gold(III) chloride as the catalyst (Scheme 45). Electron-rich arenes are, in some cases, good nucleophiles [135][136]. An interesting gold-catalyzed electrophilic addition to an arylalkyne for the synthesis of substituted naphthalenes 255 has been developed [137

Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

• Vadim A. Soloshonok and
• Donna J. Nelson

Beilstein J. Org. Chem. 2011, 7, 744–758, doi:10.3762/bjoc.7.85

• selenenylation; asymmetric synthesis; calculations; electronic effects; regioselectivity; relative reactivities; steric effects; Introduction Electrophilic addition to alkenes is one of the most fundamental, generalized, and versatile methods for selective functionalization of hydrocarbons [1]. Despite recent

• progress [2][3] in both synthetic and theoretical investigations of electrophilic selenenylation, it still remains one of the least studied types of electrophilic addition to alkenes, in particular when compared with sulfenylation. On the other hand, electrophilic selenenylation provides for the most

Asymmetric synthesis of tertiary thiols and thioethers

• Jonathan Clayden and
• Paul MacLellan

Beilstein J. Org. Chem. 2011, 7, 582–595, doi:10.3762/bjoc.7.68

• alkene towards attack by the sulfur nucleophile. 2 Carbon–carbon bond formation 2.1 Electrophilic addition to α-thioenolates Diastereoselective alkylation of α-thioenolates has been used to prepare several types of enantiomerically pure tertiary thioethers [49][50][51][52][53][54]. The method of “self

• formed by deprotonation with a lithium base and treated with an electrophile. Electrophilic addition takes place diastereoselectively anti to the bulky tert-butyl group, producing oxathiolanone products 61 in excellent diastereoselectivities. Enantiopure tertiary thiols 62 can be liberated from the

• derivatives: 1) The substrate 67 must be available in an enantiomerically pure form, 2) The lithiated intermediate 68 must be configurationally stable, and 3) Electrophilic addition to give 69 must proceed with either complete retention or complete inversion of stereochemistry. 2.2.1 Configurational stability