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

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• cations and dienes [95][96]. Initially, we found that PtCl2 was an excellent catalyst for promoting these intramolecular [4C + 3C] cycloadditions between 1,3-dienes and allenes (Scheme 26) [97]. DFT calculations as well as experimental data agreed with a mechanistic pathway based on the metal activation

• , cobalt, nickel or palladium catalysts [4]. In recent years, however, platinum and particularly gold complexes have also emerged as excellent catalysts for the promotion of novel types of cycloaddition reactions, usually involving non-activated unsaturated systems (e.g., alkynes, allenes, alkenes or 1,3

• -dienes) [5][6][7][8][9][10][11][12]. Today it is well known that the excellent reactivity of these group-11 catalysts can in part be explained in terms of relativistic effects, particularly marked in the case of gold [13][14], that induce the contraction of 6s and the expansion of 5d orbitals. As a

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• domino 1,3-dipolar cycloaddition/thermal rearrangement sequence, were converted by Wittig methylenation to the corresponding vinylcyclopropanes (VCPs), which underwent rearrangement to 1,3-dienes in the presence of the Wilkinson Rh(I) complex under microwave heating. The previously unexplored Rh(I

• )-catalyzed opening of the VCP moiety embedded in an azapolycyclic system occurs at high temperature (110–130 °C) to afford the corresponding 1,3-dienes in moderate yield (34–53%). Keywords: nitrogen heterocycles; rearrangement; rhodium; small ring systems; spiro compounds; Introduction The cyclopropyl

• influence of the N-heterocyclic system on the rearrangement, some model VCPs were generated by Wittig olefination of the α-oxocyclopropane group of functionalized oligocyclic spirocyclopropane-tetrahydropyridones and converted into the corresponding 1,3-dienes by treatment with Rh(PPh3)3Cl. Results and

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• Cedric Fischmeister Christian Bruneau UMR 6226-CNRS-Université de Rennes 1, Sciences Chimiques de Rennes, Catalyse et Organométalliques, Campus de Beaulieu, 263 avenue du général Leclerc, 35042 Rennes cedex, France 10.3762/bjoc.7.22 Abstract Conjugated 1,3-dienes are important building blocks in

• synthesis of Anolignans [48] and another closely related example is shown in the preparation of Amphidinolide E [50][51] where the diene system is extended by further cross-metathesis with 2-methylpenta-1,4-diene (Figure 2). The Diels–Alder reaction is one of the most popular transformations of 1,3-dienes

• in the presence of Grubbs second generation catalyst. It was found that depending on the nature of the alkyne (terminal or internal), the regioselectivity of the cross-coupling changed. Terminal alkynes gave 1,3-dienes with a 1,3-relationship between the alkenyl substituent and the silyl group