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

• products always provided the α,ω-diphenylalkanes. Brominations The behavior of dienes towards bromine has been studied extensively and, in particular, the addition of bromine to buta-1,3-diene is discussed in most textbooks on organic chemistry [4]. Elementary bromine adds to buta-1,3-diene in halogenated

• solvents to give mostly the 1,4-addition product (ratio 1,4-/1,2-product: 7:1) [5]. Turning to substituted dienes, 2,3-dimethylbuta-1,3-diene (11) initially also provides the 1,4-adduct 12, which subsequently is saturated to the tetrabromide 13 by reaction with a second equivalent of bromine (Scheme 4) [6

• , 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

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• bicyclic dienes can act as useful chiral ligands for rhodium-catalyzed ECA reactions. In Carreira’s report, they examined the effectiveness of their diene ligand on the conjugate addition of an α,β-unsaturated amide (Scheme 15). They were able to obtain the 1,4-addition product both in high yield and

• enantioselectivity. Since the publication of these results, many different types of chiral dienes have been used in rhodium-catalyzed ECA reactions [148][149]. In 2011, Lin and co-workers reported the rhodium–diene-catalyzed asymmetric 1,4-arylation of γ-lactams [150]. Though He and co-workers previously reported a

Direct access to pyrido/pyrrolo[2,1-b]quinazolin-9(1H)-ones through silver-mediated intramolecular alkyne hydroamination reactions

• Hengshuai Wang,
• Shengchao Jiao,
• Kerong Chen,
• Xu Zhang,
• Linxiang Zhao,
• Dan Liu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2015, 11, 416–424, doi:10.3762/bjoc.11.47

• dangerous substrates bearing an azide group, and require a high reaction temperature and a long reaction time [2][10]. Recently, transition metal catalyzed hydroamination of alkynes [14][15][16][17][18][19][20][21][22][23][24][25][26], alkenes [15][27][28][29][30][31] and dienes [32][33] has been widely

Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• , Universitetskaya nab. 7–9, 199034 St. Petersburg, Russia 10.3762/bjoc.11.35 Abstract Strained azirinium ylides derived from 2H-azirines and α-diazoketones under Rh(II)-catalysis can undergo either irreversible ring opening across the N–C2 bond to 2-azabuta-1,3-dienes that further cyclize to 2H-1,4-oxazines or

• ring opening into atropoisomeric oxazolium betaines and cyclization. Azirinium ylides generated from 2,3-di- and 2,2,3-triaryl-substituted azirines give rise to only 2-azabuta-1,3-dienes and/or 2H-1,4-oxazines. Keywords: 2-azabuta-1,3-dienes; azirines; diazo compounds; nitrogen ylides; 2H-1,4-oxazines

• , rhodium carbenoids derived from α-diazocarbonyl compounds transform 2H-azirines 1 to azirinium ylides 5 (Scheme 1) which undergo facile N–C2 bond cleavage to give 2-azabuta-1,3-dienes 3. Recently we showed that the use of α-diazo-β-ketoesters 2 in these reactions, which are finished by 1,6-cyclization of

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

• 10.3762/bjoc.11.18 Abstract The cobalt(I)-catalysed 1,4-hydrovinylation reaction of allyloxytrimethylsilane and allyl alcohol with substituted 1,3-dienes leads to hydroxy-functionalised 1,4-dienes in excellent regio- and diastereoselective fashion. Those 1,4-dienols can be converted into tetrahydrofuran

• and pyran derivatives under indirect electrochemical conditions generating selenium or iodonium cations. The reactions proceed in good yields and regioselectivities for the formation of single diastereomers. Keywords: cyclic ethers; cyclisation; 1,4-dienes; electrochemistry; iodonium; selenium

• ; Introduction The reaction of terminal alkenes with 1,3-dienes under cobalt catalysis results in 1,4-dienes in a 1,4-hydrovinylation reaction. Besides cobalt, also other transition metals were described to undergo such transformations [1][2][3][4]. However, only for the cobalt-catalysed reactions a regiodiverse

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

• ]. Preparation of dienes using the Shono oxidation [23]. Combination of an electroauxiliary mediated anodic oxidation and RCM to afford spirocyclic compounds [76]. Total synthesis of (+)-myrtine (66) using an electrochemical approach [78]. Total synthesis of (−)-A58365A (70) and (±)-A58365B (71) [79]. Anodic

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

• the resultant dienes [19]. We are not aware however of straightforward carbene additions having been explored with olefin-terminated SAMs. The potential for product cyclopropanes offered a modification of limited steric impact, but if suitably substituted may be used to tune surface properties

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

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

• 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

• . Principle of indirect electrolysis. Anodic intramolecular cyclization of olefines in methanol. Anodic cyclization of olefines in CH2Cl2/DMSO. Intramolecular coupling of 1,6-dienes in CH2Cl2/DMSO. Cyclization of bromopropargyloxy ester 12. Proposed mechanism for the radical cyclization of bromopropargyloxy

Synthesis of nanodiamond derivatives carrying amino functions and quantification by a modified Kaiser test

• Gerald Jarre,
• Steffen Heyer,
• Elisabeth Memmel,
• Thomas Meinhardt and
• Anke Krueger

Beilstein J. Org. Chem. 2014, 10, 2729–2737, doi:10.3762/bjoc.10.288

• ortho-quinodimethanes. These can be used as dienes in Diels–Alder reactions with π-bonds on the surface of nanodiamond. The use of pyrazine 3 results in a significantly increased grafting rate compared to other aromatic moieties linked by carbon–carbon bonds. Furthermore, a modified Kaiser test for the

Selenium halide-induced bridge formation in [2.2]paracyclophanes

• Laura G. Sarbu,
• Henning Hopf,
• Peter G. Jones and
• Lucian M. Birsa

Beilstein J. Org. Chem. 2014, 10, 2550–2555, doi:10.3762/bjoc.10.266

• substructure. The reactions have been found to be sensitive to the substitution of the ethynyl group. The formation of dienes with a zig-zag configuration is related to that observed for non-conjugated cyclic diynes of medium ring size. Keywords: acetylenes; dienes; [2.2]paracyclophane; selenium halides

• in situ prepared SeCl2 [28], in chloroform at 0 °C, a mixture of unexpected addition products has been obtained (Scheme 1). After separation by column chromatography, we assigned the structures of isomeric cyclic dienes 2 and 3 and the tetrachloro derivative 4 on the basis of 2D NMR studies and mass

• [28], in chloroform at 0 °C, provided a mixture of isomeric cyclic dienes 5 and 6, and the tetrabromo derivative 7 (Scheme 1, Table 1, entry 3) in 76% yield. Again, the structures of these compounds, as well as the configuration of diene 5, have been established on the basis of 2D NMR studies, mass

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• used as dienes in DA reactions; this may be because of their inverse-electron demand thus restricting them to DA reactions with electron-rich dienophiles. During our studies we noticed that pentachloro-5-methylcyclopentadiene (1) underwent a smooth DA reaction with styrenes (Table 1). We then prepared

Formal total syntheses of classic natural product target molecules via palladium-catalyzed enantioselective alkylation

• Yiyang Liu,
• Marc Liniger,
• Ryan M. McFadden,
• Jenny L. Roizen,
• Jacquie Malette,
• Corey M. Reeves,
• Douglas C. Behenna,
• Masaki Seto,
• Jimin Kim,
• Justin T. Mohr,
• Scott C. Virgil and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2014, 10, 2501–2512, doi:10.3762/bjoc.10.261

• ]. Optimal conversions and enantioselectivities were achieved from triethylsilyl enol ether 26 on exposure to [Pd(dmdba)2] (5 mol %), (S)-t-BuPHOX (5, 5.5 mol %), and diallyl carbonate (1.05 equiv) at 25 °C, in PhMe with an equivalent of Bu4NPh3SiF2 (TBAT) [43]. Recognizing that enantioenriched α,ω-dienes

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

• undivided cell [38]. From this point on most of the research in the field of CO2 fixation was focused on this type of setup. Electrocarboxylation of conjugated dienes The electrochemical fixation of carbon dioxide in 1,3-butadiene has been extensively investigated because of the importance of adipic acid

• monomer of nylon [41][42][44][48][49]. The general mechanism of CO2 fixation in conjugated dienes is illustrated in Scheme 7. It is remarkable that only one electron is used per CO2 molecule which is incorporated, making this a very energy efficient approach. There are two possible pathways to reach the

• membrane allowed the use of high CO2 pressures, pushing the selectivity towards the C6 product, completely eliminating C10 formation [49]. The above-mentioned benefits of sacrificial anode systems have lead to the electrocarboxylation of various other conjugated dienes [49][50][51][53][54]. In order to

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

• diverse trans-β-lactams that are complimentary to the related cis-lactams. 2.10 [4 + 1] Annulations of MBH carbonates with dienes Phosphine-catalyzed asymmetric [4 + 1] annulations between MBH carbonates and activated dienes could be achieved when using the bifunctional phosphine G6 as the catalyst

• H14, Zhong and Loh developed asymmetric [4 + 2] annulations of activated N-sulfonyl-1-aza-1,3-dienes and alkenes through tandem RC/Michael reactions (Scheme 51) [94]. In the presence of 10 mol % of H14, various 1-aza-1,3-dienes smoothly underwent [4 + 2] annulations with enones in chloroform at room

• temperature, affording a broad spectrum of densely functionalized tetrahydropyridine derivatives, with exclusive 4,5-trans diastereoselectivity, excellent enantioselectivity, and good to excellent yields. The transformations tolerated a wide range of N-sulfonyl-1-aza-1,3-dienes with different C4-substituents

Relay cross metathesis reactions of vinylphosphonates

• Raj K. Malla,
• Jeremy N. Ridenour and
• Christopher D. Spilling

Beilstein J. Org. Chem. 2014, 10, 1933–1941, doi:10.3762/bjoc.10.201

• metathesis reactions (Scheme 3), this approach to the synthesis of cetrolobine appeared to have little merit. However, Hoye et al. reported the concept of “relay ring closing metathesis (RRCM)”, wherein typically unreactive α,ω-dienes bearing 1,1-disubstituted ethylene moieties 9 would react via the

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• diazo esters with 5-alkoxyisoxazoles is a good approach to 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes. The reaction conditions for the preparation of aryl- and halogen-substituted 2H-1,3-oxazines and 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes from isoxazoles were investigated. Keywords: diazo esters

• ; isoxazoles; isoxazolium N-ylides; 2-azabuta-1,3-dienes; 2H-1,3-oxazines; Introduction Isoxazoles are versatile building blocks, which have found extensive use in organic synthesis [1][2][3]. However, reactions of isoxazoles with diazo compounds have scarcely been studied [1][2][3][4][5]. In 2008 Davies and

• -oxazines. In contrast, 1,4-di(methoxycarbonyl)-2-azabuta-1,3-dienes are much more stable than the corresponding 1,3-oxazines. We also evaluated the possibility of an attack of methoxycarbonylcarbene on the isoxazole oxygen. According to calculations (see Supporting Information File 1) a carbene attack on

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• , readily act in subsequent reactions as Michael acceptors, Diels–Alder (hetero)dienes or dienophiles, or dipolarophiles. Multicomponent domino reactions initiated by the Knoevenagel condensation are a valuable tool for the construction of many compounds with complex molecular structures [90]. The syntheses

• nucleosides 93 were also prepared by this method. 7. The carbopalladation of dienes A reaction of an aryl halide, an unsaturated alkene (diene, allene), and an amine catalyzed by Pd(0) species, referred to as carbopalladation of dienes, results in the three-component assembly of an unsaturated amine (Scheme

•  38) [112]. The palladium-catalyzed reactions of 5-iodopyrimidines, various acyclic or cyclic dienes, and amines were optimized by Larock et al. [113]. Thus, coupling of 5-iodo-2'-deoxyuridine (94a) or 3',5'-di-O-acetyl-5-iodo-2'-deoxyuridine (94b) with 1,2-, 1,3- or 1,ω-dienes 95, and morpholine

Chemistry of polyhalogenated nitrobutadienes, 14: Efficient synthesis of functionalized (Z)-2-allylidenethiazolidin-4-ones

• Viktor A. Zapol’skii,
• Jan C. Namyslo,
• Mimoza Gjikaj and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2014, 10, 1638–1644, doi:10.3762/bjoc.10.170

• released. Moreover, nitrodiene 1 was subjected to a vinylic substitution with ethyl 2-mercaptopropanoate to give ethyl 2-[(1,3,4,4-tetrachloro-2-nitrobuta-1,3-dien-1-yl)thio]propanoate (29) as an inseparable mixture of Z- and E-isomers in a 4:1 ratio with 78% total yield. Treatment of dienes (Z,E)-29 with

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

• Nathan J. Gesmundo and
• David A. Nicewicz

Beilstein J. Org. Chem. 2014, 10, 1272–1281, doi:10.3762/bjoc.10.128

• Nathan J. Gesmundo David A. Nicewicz Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA 10.3762/bjoc.10.128 Abstract Triarylpyrylium salts were employed as single electron photooxidants to catalyze a cyclization–endoperoxidation cascade of dienes

• challenges. Classical approaches to the introduction of cyclic peroxides typically rely on cycloadditions of alkenes and dienes with singlet oxygen. However, ene processes can often compete, leading to complex mixtures of hydroperoxide adducts [1][6][7][8]. More recently, cyclization reactions of

• were inspired by the work of Miyashi, who, during the course of the investigation of the cation radical Cope rearrangement, discovered an intriguing endoperoxide-forming reaction (Scheme 1, reaction 1). Upon exposure of 1,5 and 1,6-dienes to catalytic quantities of 9,10-dicyanoanthracene (DCA) under UV

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• phosphinating agents to react with unactivated or activated alkenes, dienes and alkynes. Hydrophosphination has gained much interest as an alternative to the classical phosphine syntheses involving a substitution that is incompatible with certain functional groups. Moreover the addition of P–H to an unsaturated

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

• 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

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

• Armin Tröger,
• Teris A. van Beek,
• Martinus E. Huigens,
• Isabel M. M. S. Silva,
• Maarten A. Posthumus and
• Wittko Francke

Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72

• Supporting Information File 1, Figure S1). However, it soon became clear that the natural product was not among the synthetic compounds 14, because their mass spectra basically showed the same differences to that of A (presence of m/z 180, absence of m/z 153) as did the 2,6,8,12-tetramethyltrideca-2,4-dienes

• Trichogramma turkestanica, as did the extract of females [12]. Published 70 eV EI mass spectra of the naturally occurring compounds A and B [12]. Synthesis of tetramethyltrideca-2,4-dienes 8, 14 and 15. Conditions: a: LiAlH4, Et2O, −30 °C to rt, 12 h; b: 1) NaH, THF, −20 °C to rt 1 h; 2) TBDMSCl (1 equiv), rt

• h; 2) BnBr (1 equiv), n-Bu4NI, 0 °C to rt, 16 h; i: PCC, MS 4 Å, DCM, −20°C, 90 min; j: [(E)-1-methylbut-2-en-1-yl]triphenylphosphonium bromide, n-BuLi, THF, −40 °C, 14 h; k: H2, 20 bar, 10% Pd/C, pentane, rt, 18 h. 70 eV EIMS of synthetic tetramethyltrideca-2,4-dienes 8, 14 and 15. These spectra

Phosphinate-containing heterocycles: A mini-review

• Olivier Berger and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2014, 10, 732–740, doi:10.3762/bjoc.10.67

• McCormack reaction of conjugated dienes, the sila-Arbuzov reaction of bis(trimethylsiloxy)phosphine with dihalides, etc. continue to be useful. However, novel approaches in both the preparation of acyclic precursors and the reactions to achieve their heterocyclization, have led to more efficient synthesis

One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines

• Christian Muschelknautz,
• Robin Visse,
• Jan Nordmann and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 599–612, doi:10.3762/bjoc.10.51

• convergent strategies paved the way to luminescent push–pull dienes 1–4 with conformationally flexible and fixed acceptor units (Figure 1) [30][31][32], pyrazoles [33][34], benzodiazepines [35], furans and pyrroles [36][37] by consecutive multicomponent reactions and to highly emissive spirocycles [38][39

• ], Fischer’s base gives rise to the formation of a mixture of E,E- and E,Z-configured push–pull dienes with 3-styryl substituents in narrow diastereomeric ratios ranging from 52:48 to 62:38 (Table 1, entries 1–5) as indicated by the appearance of a second set of many signals in the proton and carbon NMR

• spectra. The structures of the 1-styryleth-2-enylideneindolones 8 were assigned by NMR, mass spectrometry and by combustion analysis. The diastereomeric ratios of the E,E- and E,Z-configured push–pull dienes 8 were determined by integration of the distinct signals of the corresponding pairs of geminal

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• dienes and polyenes [44][50][51][52][53][54][55][56][57]. When triphenylvinylzirconocene 4a was reacted in the presence of CuCl and TCQ, the 1,1,2,3,4,4-hexaphenyl-1,3-butadiene (5) was formed in 43% isolated yield (Scheme 5). It is noteworthy that in this reaction two molecular alkynes and two