Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

• Ivan Šnajdr,
• Kamil Parkan,
• Filip Hessler and
• Martin Kotora

Beilstein J. Org. Chem. 2015, 11, 1392–1397, doi:10.3762/bjoc.11.150

• homodimerization of the starting alkenes 2 and 8 has not been observed under the reaction conditions used (however, we cannot exclude that minor undetected amounts of homodimers of 2 or 8 were formed), they could be preliminarily considered as type II or III olefins according to the Grubbs classification of

• olefins [45]. Alkenes 3 used in cross-metathesis reactions with 2. Synthesis of vinyl C-deoxyribosides α-2 and β-2. Hydrogenation of β-4b–β-4d to β-5b–β-5d. Deprotection of β-4e and β-5b to β-6e and β-7b. Conditions tested for cross-metathesis of α-2 with 3a. Cross-coupling of 2α and β-2 with alkenes 3

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

• ]. Having the sulfide 5 in hand, our next task was to prepare sulfone 6. In this regard, Trost and Curran [32] have reported the conversion of sulfides to sulfones in the presence of other common functional groups such as olefins by reacting with the oxidizing agent, potassium hydrogen persulfate (KHSO5

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

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

• lamp in deuteriochloroform. The only process that we could observe was a “polymerization” reaction, which slowly destroyed the substrate. Likewise, no photocyclization to the divinylcyclobutene derivate 51 was noted. [2 + 2] Photodimerizations of olefins have often been described, whether in solution

Cathodic hydrodimerization of nitroolefins

• Michael Weßling and
• Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

• the group of activated alkenes that can be hydrodimerized by cathodic reduction. There are many olefins with different electron withdrawing groups used for cathodic hydrodimerization, but not much is known about the behaviour of the nitro group. Synthetic applications of this group could profit from

• formation; 1,4-dinitrocompounds; electrosynthesis; nitroalkene; Introduction Olefins being activated by an electron withdrawing group can be hydrodimerized by cathodic reduction [1][2]. Thereby, the cathode serves as cheap, versatile, immobilized and mostly non-polluting reagent providing economical and

• without hydrogenating the C–C double bond. The hydrodimerization of nitro olefins should lead to 1,4-dinitroalkanes following the regioselectivity found in other hydrodimerizations of activated olefins [1][2]. Thereby, the proton concentration in the electrolyte should be not too high, as otherwise the

Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki–Heck cross-coupling reaction

• Jerzy Zakrzewski and
• Bogumiła Huras

Beilstein J. Org. Chem. 2015, 11, 1155–1162, doi:10.3762/bjoc.11.130

• been obtained using the Mizoroki–Heck cross-coupling reaction between aryl halides and an olefin [7][13][14][15][16][17]. Because cinnamates themselves are also olefins, they can serve as cinnamic substrates to synthesize more complex cinnamates [18][19]. Cinnamic acid derivatives are also formed when

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• [8]. The way towards a really complete organo-type photoredox catalysis has mainly been established for eosin Y as an important alternative for [Ru(bpy)3]2+ [9]. Photocatalytic nucleophilic additions of amines and alcohols to olefins, especially styrenes, became an increasingly important task due to

• /70s, and Lewis identified exciplex states as key intermediates [13][14]. The corresponding photohydration worked only if the aromatic olefins as starting material were directly excited by UV light [15][16]. The first approach towards a photocatalytic version of this type of reaction came from Arnold

• , Maroulis et al. [17][18]. They demonstrated that electron-rich naphthalenes are able to photoinitiate methanol additions to olefins into the Markovnikov orientation and proposed an oxidative electron transfer mechanism for this process [17]. Complementarily, electron-poor naphthalenes yielded the anti

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

Ruthenium-catalyzed C–H activation of thioxanthones

• Danny Wagner and
• Stefan Bräse

Beilstein J. Org. Chem. 2015, 11, 431–436, doi:10.3762/bjoc.11.49

• (Table 2, entry 4). This and all the products obtained exhibit exclusively n-alkylation – branched alkyl chains originating from addition at the 2-position were not found. Other olefins like 1-hexene (4b) or 3-phenylpropene (4c) also worked smoothly (Table 2, entries 5 and 6). In addition, the silyl

• -substituted olefin 4d was also successfully used in this reaction (Table 2, entry 7). The product 1bd is formed in good yield, however, it is prone to hydrolysis thus the isolated yield of the pure product was rather low. In contrast to literature precedence for other carbonyl compounds [19], other olefins

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

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

• oxygen is possible. A stereoselective electrochemical method of the chlorination of steroidal Δ5-olefins was described by Takayama et al. [38]. The oxidation of cholesterol was carried out in an undivided cell under constant current conditions in CH2Cl2/MeCN/H2O (2:2:1), the cathode and anode being

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• olefins [17]. Two examples are given in Scheme 2 [11]. A yield for the reactions is given for an experiment using photovoltaics as the power supply and a comparable reaction using a more traditional electrochemical setup. The photovoltaic-based reactions were conducted by adjusting the area of the

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

• + or I+ and DMSO to unsymmetrically substituted olefins 2c and 2d regioselectively gave bromohydrins as single regioisomers (Table 2, entries 5–10). The regioselectivity of the products can be explained by the stability of carbocations (benzyl > secondary > primary). In the case of terminal alkene 2c

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• radical initiating agent such as distannane (Scheme 6). This allows the N-acyliminium ion to react with an alkyl halide to generate the typical carbon–carbon products of the Shono oxidation [19][27][28] Examples of reactions with activated olefins have been reported using the generation of carbon free

Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs)

• Malgorzata Adamkiewicz,
• David O’Hagan and
• Georg Hähner

Beilstein J. Org. Chem. 2014, 10, 2897–2902, doi:10.3762/bjoc.10.307

• reactions demonstrate that these organic chemical transformations, which have been relatively widely used in solution reactions of olefins, can be extended to surface reactions of SAMs. This opens up prospects too of modifying surfaces in this manner with carbenes carrying more elaborate functional groups

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• anodic oxidation of electron-rich olefins such as enol ethers 1 in methanolic solution generates radical cation 2 which can be used for a number of cyclization reactions (Scheme 2) [32][33]. Moeller et al. demonstrated that by intramolecular trapping of this highly reactive intermediate with a tethered

• approach, the anodic oxidation of olefins was combined with a sequential chemical oxidation in a one-pot fashion (Scheme 3) [39]. By using DMSO instead of methanol as nucleophilic co-solvent for electrolysis, a pool of alkoxysulfonium ions 7 is generated from tosylamine 5. The generation of the cation pool

• oxidation into the anodic cyclization of olefins was extended to intramolecular coupling of 1,6-dienes 9 (Scheme 4) [39]. In this version of the combined cyclization/oxidation, the second carbon–carbon double bond acts as the nucleophile after anodic oxidation, leading to bisalkoxysulfonium species 10. When

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

• electrons per CO2 molecule, as shown in Scheme 3 for olefins, with the C–C bond formation highlighted in bold. Industrial organic electrosynthesis The chemical industry is devoting increasing research efforts to the field of organic electrosynthesis [31]. An extended series of electro-organic processes have

• and lead to a decrease in faradaic efficiency. Electrocarboxylation, the electrochemical fixation of carbon dioxide in organic chemicals, involves the electroreduction of carbon dioxide and/or an organic substrate. For olefins, alkynes, carbonyl compounds, imines and organic halides, this leads to the

• difficult to reproduce [42][46]. At that time, various substrates, like olefins, alkynes and aromatic ketones, have been electrocarboxylated in these divided cells [47]. Shortly after, sacrificial anodes made the use of a diaphragm obsolete, giving satisfactory product yields and current efficiencies in an

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• hydroformylation [22] of α-olefins [23][24][25][26][27][28][29]. By favouring the formation of singly phosphorus-ligated complexes, these ligands not only improve the catalyst activity, but also its regioselectivity, the branched regioisomer(s) being formed at the expense of the linear one. However, when it comes

A modular phosphate tether-mediated divergent strategy to complex polyols

• Paul R. Hanson,
• Susanthi Jayasinghe,
• Soma Maitra,
• Cornelius N. Ndi and
• Rambabu Chegondi

Beilstein J. Org. Chem. 2014, 10, 2332–2337, doi:10.3762/bjoc.10.242

• generates five polyol fragments, bearing differential Z- and E-olefins, from a pair of olefinic-alcohol components A and B and a pseudo-C2-symmetric phosphoryl chloride (S,S)-1. Moreover, the method relies on simple "order of addition" of components for the phosphoryl coupling, ring-closing metathesis (RCM

• Z-olefins in very good yields, while in contrast, diimide reduction in the presence of phosphate intermediates did not hydrogenate the endocyclic olefin even when large excesses of diimide reagent were employed (30 equiv). This empirical result further substantiates the protecting group ability of

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

• reaction furnished olefins 2a and 2b after acetylation in quantitative yield (Scheme 1). In the gluco-case a yield of 70% for 2c was obtained owing to incomplete consumption of the starting material 1c. Ozonolysis of the olefins 2 was performed using thiourea as reducing agent. Subsequently the generated 2

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• developed, asymmetric variants exist for only a few of them. In particular, chiral phosphine-catalyzed [3 + 2] annulations of allenes, alkynes, and MBH adducts with electron-deficient olefins and imines, resulting in cyclopentenes and pyrrolidines, have been the most studied, with many successful reported

• chiral bicyclic phosphine A2 to achieve asymmetric [3 + 2] annulations between several allenoates and electron-deficient olefins in benzene at room temperature with excellent regioselectivities (1:2 >94/6) and enantioselectivities (1, 69–93% ee). This catalyst features a rigid bridged [2.2.1] bicyclic

• spirocyclic compounds containing two neighboring quaternary and tertiary stereocenters in modest to excellent yields (up to 97%) and high enantioselectivities (up to 95% ee). Subsequently, the Fu group applied this approach to the [3 + 2] annulation of allenes with 1,1-disubstituted olefins to synthesize

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

• , terminal olefins 30 and threo-9 underwent chlorocyclisation most probably due to the presence of an excess of chloride anions (Table 1, entries 10 and 11). Interestingly, this chlorocyclisation reaction proceeded with high trans-diastereoselectivity, which is in accordance with Wolfe´s TS model [17][18

• stereoselective PdII–CuII-catalysed cyclisation [22] and its substrate scope has been investigated. The bicyclisation reaction appears to be applicable only to terminal olefinic substrates, while the reaction of alkenols bearing nonterminal and/or disubstituted olefins did not provide bicyclisation products

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

• N,N’-dialkylethane-1,2-diamine phosphonamide 24 (Scheme 1 and Scheme 2). The reaction of anions 29 with ketones leads to the corresponding β-hydroxy phosphonamide intermediates 30, which undergo elimination of the intermediate oxaphosphetanes to give chiral olefins 31 with moderate to high

Sacrolide A, a new antimicrobial and cytotoxic oxylipin macrolide from the edible cyanobacterium Aphanothece sacrum

• Naoya Oku,
• Miyako Matsumoto,
• Kohsuke Yonejima,
• Keijiroh Tansei and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2014, 10, 1808–1816, doi:10.3762/bjoc.10.190

• the olefins was determined as E for Δ10 and Z for Δ15 based on the coupling constants JH10,H11 ~ 15.8 Hz and JH15,H16 ~ 10 Hz, respectively. The former spin system (O-H13-H214-H15=H16-H217-H318) had a methyl group at one end and was therefore deemed to constitute a side chain group, whereas the latter

Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction

• Marina Rubina,
• William M. Sherrill,
• Alexey Yu. Barkov and
• Michael Rubin

Beilstein J. Org. Chem. 2014, 10, 1536–1548, doi:10.3762/bjoc.10.158

• to design a very efficient and highly selective catalytic system. Employment of the optimized ligands in the asymmetric arylation of cyclic olefins allowed for achieving high enantioselectivities and significantly suppressing product isomerization. Factors affecting the selectivity and the rate of

• Guiry [57][58] (Figure 2) were employed in the asymmetric Heck reaction of different cyclic olefins. Furthermore, Gilbertson demonstrated PHOX ligands featuring apobornene backbone (Figure 2) exhibit outstanding activities and selectivities in the arylation and alkenylation of different cyclic

• novel PHOX ligands featuring a chiral cyclopropyl backbone have been synthesized and examined in the intermolecular asymmetric Heck arylation of cyclic olefins. By lowering degrees of freedom in the catalyst structure through the introduction of additional conformation constrains, we have created a

Postsynthetic functionalization of glycodendrons at the focal point

• Thisbe K. Lindhorst and
• Katharina Elsner

Beilstein J. Org. Chem. 2014, 10, 1482–1487, doi:10.3762/bjoc.10.152

• -configured alkenes were the only cross-coupling products obtained. This might be due to the specific structure of the used substrates, as sterically hindered olefins are known to enhance trans-selectivity in metathesis [12]. The same reactions were successful with the tetravalent glycodendron 9 yielding the