One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• acid to afford 241 in almost quantitative yield. Bicyclic endoperoxides generated from the cycloaddition of singlet oxygen to 1,3-dienes serve as excellent synthetic precursors and have led to developments in tropone chemistry [170][171][172]. Taking advantage of the endoperoxide transformation, the

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• were several reported examples of intra- or intermolecular Wittig reactions of ylides generated from dialkyl acetylenedicarboxylate, triphenylphosphine, and some nucleophiles. Thus, Yavari and Asghari reported an interesting synthesis of highly electron-deficient 1,3-dienes in the reaction of

• the final 1,3-dienes 89 (Scheme 54) [21]. A similar type of highly electron-deficient 1,3-dienes 90 were synthesized in yields of 78–87% in an analogous reaction with ethyl 4-aryl-2,4-dioxobutanoates with the corresponding vinylphosphonium salt (Scheme 55) [68]. In a similar reaction employing ethyl 3

• -aminothiophenol. Synthesis of 1,3-dienes via intramolecular Wittig reaction with the use of resonance-stabilized ylides generated from acetylenedicarboxylates, triphenylphosphine, and acetoacetanilide. Synthesis of 1,3-dienes in the intramolecular Wittig reaction from ylides generated from dimethyl

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• observed by 1H NMR spectroscopy [8]. Similar systems were prepared on solid phase and used as a new molecular recognition system [44]. The [4 + 2]-cycloaddition reactions of E- and Z-1b with electron-rich 1,3-dienes have been studied extensively by Sustmann and collaborators. Thus, 1-methoxybuta-1,3-diene

• isomerization to E-1b, induced by the basic nature of the Me2N group, is a likely explanation for the observed result. In extension of the study with amino-substituted electron-rich 1,3-dienes, reactions were also performed with 1,4-bis(dimethylamino)buta-1,3-diene. These required low temperature (ca. −50 °C

• ) to avoid the formation of complex product mixtures. Based on the 1H NMR analysis, only one product, identical in reactions with E- and with Z-1b, was formed [47]. Also bis(dimethylamino)-substituted 1,3-dienes including bicyclic representatives were used for reactions with E- and Z-1b [48][49

Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

Beilstein J. Org. Chem. 2017, 13, 2157–2159, doi:10.3762/bjoc.13.215

• magnetic resonance imaging (MRI) [22]. Well-defined fluorescent polyrotaxanes with alternating, threaded cucurbit[6]uril and CD rings were assembled by Fraser Stoddart’s group via an alkyne–azide click reaction exploiting supramolecular catalysis [23][24]. The concurrent radical copolymerization of 1,3

• -dienes and bulky stoppers in the presence of CDs (so-called rotaxa-polymerization) was further applied for the syntheses of water-soluble polyisoprene polyrotaxanes [25]. Furthermore, ABA-type block-copolyrotaxanes could be synthesized using this polymerization technique controlled by RAFT chain transfer

Pd(OAc)₂/Ph₃P-catalyzed dimerization of isoprene and synthesis of monoterpenic heterocycles

• Dominik Kellner,
• Maximilian Weger,
• Andrea Gini and
• Olga García Mancheño

Beilstein J. Org. Chem. 2017, 13, 1807–1815, doi:10.3762/bjoc.13.175

• dimerization reactions of other 1,3-dienes are reported. In this regard, isoprene has recently attracted great attention as interesting branched C5-derivative for such dimerization processes. Isoprene is a broadly used, valuable chemical for the industry [16][17]. It is used for the synthesis of rubber and

• (PhI=NR) under metal catalysis [43][44][45][46]. Although the formal [4 + 1]-cycloaddition with 1,3-dienes has been already described [47], isoprene dimers have not been enrolled as substrates in such type of reaction since the presence of the additional, less hindered double bond could lead to

• for alkyl and aryl mono-, bi- and tri-substituted 1,3-dienes with N-(p-tolylsulfonyl)imino]phenyliodinane (PhI=NTs) [37]. To our delight, the desired 3-pyrroline 7 was obtained as major product in a good 71% yield. Conclusion In summary, a simple and practical Pd-catalyzed dimerization of isoprene has

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• provide the biggest number of carbon atoms during the synthesis of the 1-indanone benzene ring. For instance, 1,3-dienes in the Diels–Alder reaction provide 4 carbon atoms of the six ones needed to construct the benzene ring of 1-indanone compared to dienophiles which deliver only two of them. 2.1 From

• 1,3-dienes Wolf and Xu have synthesized 7-methyl substituted 1-indanone 241 utilizing 1,3-pentadiene (238) and 2-cyclopentenone (239) as starting compounds [96]. 7-Methyl substituted 1-indanone 241 has been obtained in the Diels–Alder reaction between 1,3-pentadiene (238) and 2-cyclopentenone (239

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• 4:1 in the presence of 4 Å molecular sieves (Scheme 59) [97]. A sequential three-component enamine–azoene annulation reaction of primary aliphatic amines 292, activated methylene compounds 293, and 1,2-diaza-1,3-dienes (DDs, 294) has been reported to give polysubstituted pyrroles 295 (Scheme 60) [98

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• -fused pyran-3-ones and the results are reported herein. Results and Discussion For a long time, the Diels–Alder reaction of simple heterosubstituted 1,3-dienes has been considered a standard procedure to prepare highly functionalized ring systems [28]. Taking advantage of diazalactones to act as the

Tandem cross enyne metathesis (CEYM)–intramolecular Diels–Alder reaction (IMDAR). An easy entry to linear bicyclic scaffolds

• Javier Miró,
• María Sánchez-Roselló,
• Álvaro Sanz,
• Fernando Rabasa,
• Carlos del Pozo and
• Santos Fustero

Beilstein J. Org. Chem. 2015, 11, 1486–1493, doi:10.3762/bjoc.11.161

• to generate conjugated 1,3-dienes under mild conditions. These 1,3-dienes are versatile building blocks suitable for further non-metathetic transformations, either in a step-wise or a tandem fashion. Thus, the enyne metathesis methodology has become a powerful tool for the generation of carbon–carbon

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

• ; 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

• -dienols could be generated from simple 1,3-dienes, such as 1,3-butadiene or 1-aryl-substituted 1,3-dienes 1, and TMS-protected allylic alcohol (Scheme 1) for the synthesis of 1,4-dienols of type 2. The cobalt-catalysed hydrovinylation reaction is highly regiospecific for the carbon–carbon bond formation

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

• 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

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

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• , CS 50837, 35708 Rennes Cedex 7, France Centre for Sustainable Chemical Processes, Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K. 10.3762/bjoc.10.19 Abstract In the last few years, multicomponent reactions involving boron substituted 1,3-dienes have emerged as important

• tools in synthetic organic chemistry. The most significant recent results and developments obtained in this area are reported in this review. Keywords: allylboration; boron compounds; Diels–Alder; 1,3-dienes; multicomponent reactions; Petasis borono–Mannich; Suzuki couplings; Introduction

• other amine partners [13][14][15]. Subsequently, other multicomponent reactions involving trialkylborane [16][17], alkenyl- [18][19], aryl- [20][21], allyl- [22], allenyl- [23], and alkynylboronic acids or esters [24][25][26] have been reported in the literature. Boron-substituted 1,3-dienes and

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

One-pot cross-enyne metathesis (CEYM)–Diels–Alder reaction of gem-difluoropropargylic alkynes

• Santos Fustero,
• Paula Bello,
• Javier Miró,
• María Sánchez-Roselló,
• Günter Haufe and
• Carlos del Pozo

Beilstein J. Org. Chem. 2013, 9, 2688–2695, doi:10.3762/bjoc.9.305

• for the creation of carbon–carbon bonds has exponentially increased, due to the availability of well-defined catalysts [1][2][3]. Particularly, enyne metathesis (EYM) is a powerful synthetic tool for generating 1,3-dienes by redistributing unsaturated functionalities between an alkene and an alkyne

• probably due to its inherent problems of selectivity, which results in the formation of a mixture of E- and Z-isomers [14]. The discovery of the beneficial effect of ethylene has changed this tendency allowing the straightforward preparation of 1,3-dienes [15][16]. Thus, during the ethylene gas promoted

• very fruitful for the preparation of 1,3-dienes, this protocol has remained almost unexplored for propargyl fluorides [26]. In this context, we have recently established a tandem multicomponent protocol CEYM–Diels–Alder reaction of several difluoropropargylic derivatives [27][28] mediated by 1,7

Consecutive cross-coupling reactions of 2,2-difluoro-1-iodoethenyl tosylate with boronic acids: efficient synthesis of 1,1-diaryl-2,2-difluoroethenes

• Ju Hee Kim,
• Su Jeong Choi and
• In Howa Jeong

Beilstein J. Org. Chem. 2013, 9, 2470–2475, doi:10.3762/bjoc.9.286

• yields. Unsymmetrical di-coupled products 4 were obtained in high yields from the reactions of 3 with 2 equiv of boronic acids in the presence of catalytic amounts of Pd(OAc)2 and Na2CO3. Keywords: boronic acids; cross-coupling reaction; 1,1-diaryl-2,2-difluoroethene; 1,1-difluoro-1,3-dienes; 2,2

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• -tuning of the catalyst and substrate is required to achieve excellent enantioselectivities. More recently, Nevado and co-workers have shown that propargyl acetates 4 react with 1,3-dienes in the presence of a gold catalyst to give good yields of cycloheptadiene products of type 5; thus the process could

Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η¹-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results

• Rajendra K. Jangid,
• Nidhi Sogani,
• Neelima Gupta,
• Raj K. Bansal,
• Moritz von Hopffgarten and
• Gernot Frenking

Beilstein J. Org. Chem. 2013, 9, 392–400, doi:10.3762/bjoc.9.40

• could be enhanced by complexing the P-atom of phosphinine to a metal carbonyl, such as W(CO)5 [15][20]. Thus, the phosphinine-η1-P-W(CO)5 complex reacted with 1,3-dienes to afford [2 + 4] cycloadducts. By following the same strategy, we recently reported our theoretical and experimental results of the

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• compounds. Manganese-catalyzed allylmagnesiation of allenes. Copper-catalyzed alkylmagnesiation of 1,3-dienes and 1,3-enynes. Chromium-catalyzed methallylmagnesiation of 1,6-diynes. Chromium-catalyzed allylmagnesiation of 1,6-enynes. Proposed mechanism of the chromium-catalyzed methallylmagnesiation. Copper

Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols

• Marcin Jasiński,
• Dieter Lentz and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2012, 8, 662–674, doi:10.3762/bjoc.8.74

• the level of diastereoselectivity was only low to moderate, and the interpretation should therefore not be exaggerated. Alternative conformations explaining the results are certainly possible. The fragmentation of the primarily formed allenyl N-hydroxylamines of type 2 leading to 1,3-dienes such as 4

Alkoxide-induced ring opening of bicyclic 2-vinylcyclobutanones: A convenient synthesis of 2-vinyl-substituted 3-cycloalkene-1-carboxylic acid esters

• Xiufang Ji,
• Zhiming Li,
• Quanrui Wang and
• Andreas Goeke

Beilstein J. Org. Chem. 2012, 8, 650–657, doi:10.3762/bjoc.8.72

• reaction of ketenes (R2C=C=O) with alkenes under thermal conditions to give cyclobutanone products is generally described as an [π2s + π2a] process from orbital symmetry considerations. However, there is strong evidence that formation of the Staudinger-type cycloadducts by using cyclic (s-cis) 1,3-dienes

Chemistry of polyhalogenated nitrobutadienes, 10: Synthesis of highly functionalized heterocycles with a rigid 6-amino-3-azabicyclo[3.1.0]hexane moiety

• Viktor A. Zapol’skii,
• Jan C. Namyslo,
• Armin de Meijere and
• Dieter E. Kaufmann

Beilstein J. Org. Chem. 2012, 8, 621–628, doi:10.3762/bjoc.8.69

• reactions, namely the conversion of the 1-amino-2,2-dichlorovinyl group to a dichloromethyl ketone and, in addition, the reductive bisdechlorination of a dichloromethyl group were recently published by our group [5][43]. Conclusion Regioselective reactions of the nitrotrichlorobuta-1,3-dienes 3 and 4, some

Efficient synthesis of 1,3-diaryl-4-halo-1H-pyrazoles from 3-arylsydnones and 2-aryl-1,1-dihalo-1-alkenes

• Yiwen Yang,
• Chunxiang Kuang,
• Hui Jin,
• Qing Yang and
• Zhongkui Zhang

Beilstein J. Org. Chem. 2011, 7, 1656–1662, doi:10.3762/bjoc.7.195

• ], alkenyl arenes [19], 1,3-dienes [20][21], α,β-unsaturated esters [19][22] and nitriles [23], phosphane oxides [24] or with alkynyl silanes [18], stannanes [18][25][26], arenes [27][28], esters [29][30][31][32][33], boronic esters [34][35]. However, the cycloaddition of sydnones with 1,1-dihaloalkenes is