AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• species could be also involved mechanistically in the Ag-mediated reaction of enynals with conjugated dienes [18] and the homodimerization of enynals [19][20]. So, the studies on the reactions of alkynes involving the generation of silver carbene species from non-diazo precursors are of great value for

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• exocyclic C6 position have also been reported. For higher-order hepta- and nonafulvenes, the extended conjugated system also allows them to act as 8π components, as well as 2–6π components. Pentafulvenes can react as 2π components with moderately electron-deficient dienes and 4π components in reactions with

• fulvene to function as a 6π component in reactions with electron-deficient dienes (Scheme 5b) and fulvenes acting as dipolarophiles have been reported for enantioselective [6 + 3] and [3 + 2] cycloadditions [83][84][105]. In general, reactions with electron-rich alkenes will take place preferentially at

• reacting partner in the structure [91][119][127]. For example, pentafulvenes tethered to various dienes have been employed as precursors to various polycyclic ring systems, including kigelinol, neoamphilectane and kempane skeletons, which can be formed in a stereospecific manner depending upon the tether

Catalytic asymmetric oxo-Diels–Alder reactions with chiral atropisomeric biphenyl diols

• Chi-Tung Yeung,
• Wesley Ting Kwok Chan,
• Wai-Sum Lo,
• Ga-Lai Law and
• Wing-Tak Wong

Beilstein J. Org. Chem. 2019, 15, 955–962, doi:10.3762/bjoc.15.92

• reactions. Oxo-Diels–Alder (oxo-DA) reactions between electron-poor aldehydes and electron-rich dienes such as Danishefsky’s dienes or Brassard’s dienes are efficient ways to construct oxygen-containing six-membered heterocycles via [4 + 2] cyclizations, and have been dominated by metal-based chiral Lewis

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• way in lower yields [32]. The third part of this study was devoted to the demonstration of catalytic properties of metallo-complexes 11 in “standard” metathesis reactions (Scheme 6, Table 3). As a model substrate we chose easily available alkenes and dienes, such as i) styrene (12) and allylbenzene

• small amount of the starting compound 14 underwent polymerisation. The utility of the catalyst for the RCM reaction was demonstrated by the cyclization of dienes 17 and 19 (Table 3, entries 25–33) in both air and argon atmosphere. The complexes 11a, 11b and 11d in the air atmosphere provided cyclic

• alkenes 18, 20 with a strong admixture of initial dienes (Table 3, entries 25, 26, 29). Under argon atmosphere, the same transformations provided good results in the presence of 0.1–0.01 mol % of catalysts 11b,d (Table 3, entries 28, 30–32). Similarly, in the case of the ROCM reactions (Scheme 6

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• silsesquioxanes (POSS) and POSS-containing polymeric materials. Three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis polymerization (ROMP) of

• metathesis in chemistry of unsaturated derivatives of POSS is limited to three types of processes, i.e., cross metathesis (CM) of vinyl-substituted POSS with terminal olefins, acyclic diene metathesis (ADMET) copolymerization of divinyl-substituted POSS with α,ω-dienes and ring-opening metathesis

• the application of ADMET in the synthesis of oligomers or polymers containing a POSS unit in the main chain. Marciniec disclosed ADMET copolymerization of DDSQ-2SiVi with dienes in the stereoselective synthesis of a new class of vinylene–arylene copolymers containing double-decker silsesquioxanes in

Synthesis of 1,2-divinylcyclopropanes by metal-catalyzed cyclopropanation of 1,3-dienes with cyclopropenes as vinyl carbene precursors

• Jesús González,
• Alba de la Fuente,
• María J. González,
• Laura Díez de Tejada,
• Luis A. López and
• Rubén Vicente

Beilstein J. Org. Chem. 2019, 15, 285–290, doi:10.3762/bjoc.15.25

• Abstract The synthesis of 1,2-divinylcyclopropanes by the reaction of cyclopropenes with 1,3-dienes is reported. The process relies on the ability of ZnCl2 or [Rh2(OAc)4] to generate metal–vinyl carbene intermediates from cyclopropenes, which effect cyclopropanation of 1,3-dienes. Most of the reactions

• proceeded in reasonable yields while the diastereoselectivity strongly depends on the structure of the diene. An example of an intramolecular process as well as the use of furan and 1,4-cyclohexadiene as dienes are also reported. Keywords: cyclopropanation; cyclopropenes; dienes; divinylcyclopropanes

• cyclopropanecarboxaldehydes [10] or reactions of metallated vinylcyclopropanes with suitable electrophiles are commonly employed (Scheme 1a) [11][12][13]. In a more convergent approach where the cyclopropane ring is created at the last stage, divinylcyclopropanes can be prepared by cyclopropanation of 1,3-dienes with metal

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• alkylidenecyclopropanes 1 with allylic bromides 78 for the synthesis of 2-bromo-1,6-dienes 79 via radical ring-opening and SH2’ reactions (path V in Scheme 17) [95]. The experimental results suggested that radical carbonylation could also be incorporated in the reaction sequence, leading to 2-bromo-1,7-dien-5-ones 80

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• tested for the ethenolysis of cyclic olefins to selectively form α,ω-dienes, along with other 23 Ru benzylidene complexes featuring NHC ligands that differ in steric and electronic properties [50]. It is worth to underline that this transformation mediated by ruthenium initiators is less well

• investigated, presumably as a consequence of the high activity of ruthenium catalysts toward the competitive ROMP that is leading to low yields of terminal dienes. Among all the investigated systems, N-CF3 complex 153 emerged as the best performing catalyst in the ethenolysis of cis-cyclooctene (47), giving 96

• functionalized α,ω-dienes was thus accomplished in useful yields (>70%). In order to explain the selectivity observed in the ethenolysis of cyclic olefins, steric and electronic descriptors of the NHC ligands obtained computationally were evaluated. The main role in controlling selectivity was ascribed to the π

Degenerative xanthate transfer to olefins under visible-light photocatalysis

• Atsushi Kaga,
• Xiangyang Wu,
• Joel Yi Jie Lim,
• Hirohito Hayashi,
• Yunpeng Lu,
• Edwin K. L. Yeow and
• Shunsuke Chiba

Beilstein J. Org. Chem. 2018, 14, 3047–3058, doi:10.3762/bjoc.14.283

• (Table 2, entry 11), implicating that the redox process is partially operating along with the main radical chain process. Norbornene (2m) was found reactive for degenerative transfer of xanthate 1a (Table 2, entry 12). The reaction was also applied to dienes 2n and 2o, which led the formation of

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• reaction products: conjugated dienes, allyl alcohols, or thiochromene 1,1-dioxides. These reactions open new opportunities for organic synthesis based on electrophilic activation of sulfur containing allenes. X-ray crystal structures of compounds 2h (CCDC 1843276), 3e (CCDC 1843277), 5c (CCDC 1580895), 7b

Domino ring-opening–ring-closing enyne metathesis vs enyne metathesis of norbornene derivatives with alkynyl side chains. Construction of condensed polycarbocycles

• Ritabrata Datta and
• Subrata Ghosh

Beilstein J. Org. Chem. 2018, 14, 2708–2714, doi:10.3762/bjoc.14.248

• system. Domino metathesis of oxa- and aza-norbornenes with alkyne side chains [38][39][40] as well as norbornene derivatives having ether linked alkynes [41][42] in combination with Diels–Alder reaction of the resulting 1,3-dienes have been investigated to construct polycycles with heteroatoms. In spite

Ring-opening metathesis of some strained bicyclic systems; stereocontrolled access to diolefinated saturated heterocycles with multiple stereogenic centers

• Zsanett Benke,
• Melinda Nonn,
• Márton Kardos,
• Santos Fustero and
• Loránd Kiss

Beilstein J. Org. Chem. 2018, 14, 2698–2707, doi:10.3762/bjoc.14.247

• transformations, cyclic dienes with different ring sizes might be considered to be important starting materials for the generation of structurally diverse molecules. Among the large number of possible transformations, the ring olefinic bond of alicyclic dienes may lead to valuable β-lactams [21][22][23] or γ

• Recently, we have demonstrated the high utility of various constrained cyclic dienes, such as norbornadiene as well as 1,5- and 1,3-cyclooctadienes in the context of their applicability towards the access of diverse, highly functionalized olefinated molecules [14][15][16]. The corresponding β-lactams

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• with G-I catalyst 1 under ethylene, which resulted in the formation of the dienes 97a (63%) and 97b (83%, Scheme 15). Further, treatment of dienes 97a,b with dimethyl acetylenedicarboxylate (DMAD, 98) separately delivered the corresponding cycloadducts. Subsequently, aromatization was achieved by using

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• acid derivatives. Diene 14a was converted into the corresponding carboxylic acid 15a in good yield. In addition, 1,4-dienes having cyclohexenyl and geminal diphenyl substituents (14b and 14c) produced their corresponding linear carboxylic acids 15b and 15c in 78% and 57% yields, respectively. Substrate

• using alkynes [63][64][65][66], alkenes [67][68], allenes [69][70][71] and 1,3-dienes [72][73] have been reported. In this regard, Mikami et al. reported the Rh-catalyzed hydrocarboxylation of styrene derivatives depicted in Scheme 33 [74]. The desired reaction proceeded using [RhCl(cod)]2 as a catalyst

Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• to the case of nucleophilic η1-allylpalladium species [31][32][33][34][35][36][37][38][39]), whereas the cobalt atom preferred to reside at the internal position when allylarenes and 1,4-dienes were employed in our previous studies [28][29]. Subsequently, reductive elimination of methane from III

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• regioselective manner [16][20]. In cycloaddition chemistry, 1,4-quinones are applied widely both as dipolarophiles and dienophiles. In the case of [3 + 2] cycloadditions, reactions can occur chemoselectively with either the C=O or the C=C unit [21][22][23]. On the other hand, reactions with diverse 1,3-dienes

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• his process. The reaction applies to phenylacetylenes and various types of aromatic alkenes, however, its scope has been extended to dienes and disubstituted styrenes by using the less Lewis acidic CuI complex (Scheme 5b) [38]. Interestingly, cis and trans β-methyl-styrenes lead to product 14 with the

• same syn:anti ratio while 1,4-addition products containing an (E)-olefin are selectively obtained from dienes. The authors have also shown that the reaction performed in the presence of a stoichiometric amount of p-TsOH gives β-trifluoromethylstyrene derivatives instead of the expected oxy

• -trifluoromethyl compound. The benzoyloxy-trifluoromethylation of dienes has also been reported with CuCN as the catalyst. The reaction, again, is selective with respect to the olefin geometry – (E)-alkenes are exclusively obtained – and the regioselectivity – products resulting from a sterically-controlled 1,4

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• (Scheme 5). Later, this dearomatization strategy was further reinvestigated by the Ishihara group using a new chiral iodine precatalyst 10 derived from a chiral 2-aminoalcohol [39]. Its application in the oxidative dearomatization of phenol 33 and the subsequent reaction of the so-obtained dienes 34 with

• iodobiarenes to synthesize a new class of I(III) and I(V) reagents 17. These were applied for the hydroxylative dearomatization of phenolic derivatives 42 followed by the successive use of the hydroxylated products as dienes in [4 + 2] cycloaddition reactions [42]. This new reagent promoted oxygen transfer in

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

Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of vicinal-dichlorides and chlorodienes

• Zhensheng Zhao and
• Graham K. Murphy

Beilstein J. Org. Chem. 2018, 14, 796–802, doi:10.3762/bjoc.14.67

• regioselective reaction of aryl- and α-substituted phenylallenes with the hypervalent iodine (HVI) reagent 1-chloro-1,2-benziodoxol-3-one. The reaction typically results in vicinal dichlorides, except with proton-containing α-alkyl substituents, which instead give chlorinated dienes as the major product

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• depicted in Figure 2, PQS (4a) has an OH moiety that allows for its linkage to the organocatalyst proline 4b. Also, PQS has a lipophilic component that acts as a reaction solvent for hydrophobic dienes. The latter feature allows aldol reactions to take place efficiently in water. The aldol reaction between

Synthesis of a sucrose-based macrocycle with unsymmetrical monosaccharides "arms"

• Karolina Tiara,
• Mykhaylo A. Potopnyk and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2018, 14, 634–641, doi:10.3762/bjoc.14.50

• , 1487.6857; found, 1487.6971; anal. calcd for C86H100N2O19 (1465.74): C, 70.47; H, 6.88; N, 1.91; found: C, 70.62; H, 6.96; N, 1.84. Possible route to sucrose cryptands 6. Possible route to dienes of type 9. Synthesis of macrocyclic derivative 4. Unsuccessful attempts to amines 12a and 13b. Syntheses of

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• of cyclic frameworks, especially in the synthesis of natural products [1][2]. Aza-dienes have been utilized in IEDDA reactions for the construction of nitrogen-containing heterocyclic compounds [3][4][5][6][7][8]. Among them, 1,2-diazines are less used owing to their relative low reactivity as their

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

• Hisato Shimizu,
• Akira Yoshimura,
• Keiichi Noguchi,
• Victor N. Nemykin,
• Viktor V. Zhdankin and
• Akio Saito

Beilstein J. Org. Chem. 2018, 14, 531–536, doi:10.3762/bjoc.14.39

• , Winnipeg, MB R3T 2N2, Canada 10.3762/bjoc.14.39 Abstract [Bis(trifluoroacetoxy)iodo]benzene (BTI) and (diacetoxyiodo)benzene (DIB) efficiently promote the formation of acylnitroso species from hydroxamic acids in the presence of various dienes to give the corresponding hetero-Diels–Alder (HDA) adducts in

• ) reaction of N-acylnitroso species with dienes provides the facile and highly stereoselective synthesis of 1,2-oxazines, which have been widely recognized as useful synthons in the synthesis of biologically active natural products [1]. Generally, in the presence of dienes, acylnitroso species are in situ

• and Bottke’s group have demonstrated that (diacetoxyiodo)benzene (DIB) and iodosylbenzene are applicable to the ene reactions of acylnitroso species derived from hydroxamic acids [22], the iodine(III)-mediated oxidative cycloaddition reaction of hydroxamic acids with dienes is still unknown. Herein

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• poly(allyl methacrylates) with a series of functionalized thiols. Step-growth addition polymerization for the preparation of linear polymers also was achieved using dithiols and dienes for the reaction. Recently, Chung and co-workers were successful in functionalizing natural lignin by applying Yoon’s

• sulfenylated dienes by dehydration. A series of aryl thiols with different steric and electronic properties give high yields of the thiol–yne products. Noteworthy is the high E-selectivity of the resulting alkene. Dependent on the substitution pattern of the aryl thiol a ratio up to 60:1 was observed due to