Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• three-step one-pot procedure using KSeCN (2), alkyl (3) and styryl halides (4) with good yields (Scheme 1, A) [38]. This reaction proceeds through an initial nucleophilic substitution reaction between the alkyl halide and KSeCN to afford the corresponding alkyl selenocyanate (RSeCN). The treatment of

• the latter with K3PO4 generates the alkyl selenolate anion (RSe−) which reacts with another RSeCN molecule to give the corresponding diselenide R2Se2. Reduction of the latter diselenide by treatment with NaBH4 affords an alkyl selenolate anion, which reacts with styryl halide to give the desired

• styryl selenide 1. During optimization of the reaction conditions to 1 and in the presence of only t-BuOK, the corresponding alkynyl selenide 5 was obtained together with dialkyl selenides R2Se and R2Se2. In view of the important synthetic application of alkynyl selenides, we envisioned the possibility

Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid

• Anna S. Zalivatskaya,
• Dmitry S. Ryabukhin,
• Marina V. Tarasenko,
• Alexander Yu. Ivanov,
• Irina A. Boyarskaya,
• Elena V. Grinenko,
• Ludmila V. Osetrova,
• Eugeniy R. Kofanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89

• investigation of their properties are of ongoing interest in chemistry and medicine. Based on our previous works on reactions of cinnamides [24] and 5-styryl-2H-tetrazoles [25] with arenes under superelectrophilic activation with Brønsted or Lewis superacids, we turned our attention towards the hydroarylation

• of the C=C double bond in 5-styryl-substituted oxadiazoles, such as (E)-5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles 1 (Scheme 1). The main goals of the current work were to investigate the reactions of oxadiazoles 1 with different arenes under the conditions of superelectrophilic activation and to

• thermodynamic point of view, the first protonation of 5-styryl-substituted 1,2,4-oxadiazoles takes place at the N4 nitrogen atom leading to cation C (ΔG298 of this reaction has the lowest value of −59.2 kJ/mol) and the most probable dicationic species, obtained through protonation of species C, should be N4,C

A postsynthetically 2’-“clickable” uridine with arabino configuration and its application for fluorescent labeling and imaging of DNA

• Heidi-Kristin Walter,
• Bettina Olshausen,
• Ute Schepers and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2017, 13, 127–137, doi:10.3762/bjoc.13.16

• by blue and green emitting cyanine-styryl dyes were improved due to the arabino-configured anchor. These oligonucleotides were used as energy transfer donors in hybrids with oligonucleotides modified with acceptor dyes that emit in the yellow-red range. These combinations give energy transfer pairs

• developed and synthesized the 2’-propargyl-modified arabino-configured uridine analog 2, incorporated it into DNA by automated phosphoramidite chemistry, “clicked” it to a variety of our recently established, photostable cyanine-styryl dyes and probed the fluorescence and energy transfer properties by

• corresponding unmodified counterstrand. The four fluorophores D1 [23], a blue emitter excitable at 389 nm, D2 [24], D3 [19], and D4 [24], all green emitters excitable at 450–460 nm, that were “clicked” to the oligonucleotides DNA1a and DNA1r belong to our recently established class of cyanine-styryl dyes that

Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

• Michal Medvecký,
• Igor Linder,
• Luise Schefzig,
• Hans-Ulrich Reissig and
• Reinhold Zimmer

Beilstein J. Org. Chem. 2016, 12, 2898–2905, doi:10.3762/bjoc.12.289

• furnish the expected 5-styryl-substituted derivative syn-19 and the 5-aryl-substituted derivatives syn-21 and syn-22, respectively, in moderate to good yield (Scheme 6). Notably, the D-arabinose-derived 5-iodo-1,2-oxazine anti-4d was also efficiently converted into the 5-phenyl-substituted compound anti

• reactions of 1,2-oxazine syn-4a leading to 5-alkenyl-substituted 1,2-oxazines syn-13, syn-14 and to dehydroamino acid syn-17. Suzuki–Miyaura reactions of 1,2-oxazines syn-4a, syn-4b and anti-4d leading to 5-styryl-substituted 1,2-oxazine syn-19 and 5-aryl-substituted 1,2-oxazines syn-21, syn-22 and anti-24

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

• vinyl β-C-deoxyribofuranoside was based on transformation of 6-O-tert-butyldiphenylsilyl-3,5-dideoxy-5-iodo-L-lyxo-hexofuranose [14]. A reaction sequence relying on Horner–Wadsworth–Emmons/ring closure–halogenation/Ramberg–Bäcklund/Wittig reaction gave rise to the equimolar mixture of styryl α- and β-C

• -deoxyribosides on hand, the feasibility of catalytic hydrogenation was also briefly explored. Compounds possessing the heptenyl side chain (β-4b), tridecafluorononenyl side chain (β-4c), and the styryl side chain (β-4d) were chosen as substrates. In all cases the hydrogenation by using Pd/C under low pressure of

Photochemical approach to functionalized benzobicyclo[3.2.1]octene structures via fused oxazoline derivatives from 4- and 5-(o-vinylstyryl)oxazoles

• Ivana Šagud,
• Simona Božić,
• Željko Marinić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2014, 10, 2222–2229, doi:10.3762/bjoc.10.230

• )oxazole small quantities of electrocyclization product, 4-(1,2-dihydronaphthalen-2-yl)oxazole, are isolated and spectroscopically characterized. Keywords: bicyclo[3.2.1]octane; intramolecular photocycloaddition; oxazole; styryl; vinyl; Introduction The bicyclo[3.2.1]octane skeleton is the basic

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• ). To further illustrate AT reactions with aniline, the work of Dumitrascu et al. [43] is worth mentioning. Recently, they have reported on the preparation of an aryl phosphoramidate with a styryl moiety from the corresponding aniline (Scheme 15). The phosphoramidate was isolated with an excellent yield

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

• ], 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

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• alkenylation of cycloalkanes with high selectivity and stereospecificity remains a great challenge and attracted a lot of attention in the past years. In 1996, the Fuchs group described the alkenylation of cyclohexane by a radical reaction with vinyl triflone [58]. In 2003, the Yao group reported that styryl

Bioinspired total synthesis of katsumadain A by organocatalytic enantioselective 1,4-conjugate addition

• Yongguang Wang,
• Ruiyang Bao,
• Shengdian Huang and
• Yefeng Tang

Beilstein J. Org. Chem. 2013, 9, 1601–1606, doi:10.3762/bjoc.9.182

• neuraminidase (NA) inhibitor, was synthesized by using a bioinspired, organocatalytic enantioselective 1,4-conjugate addition of styryl-2-pyranone with cinnamaldehyde, followed by a tandem Horner–Wadsworth–Emmons/oxa Michael addition. Keywords: bioinspired synthesis; catalysis; katsumadain A; natural product

• katsumadai Hayata (Zingiberaceae), a chinese herbal drug used as an anti-emetic and stomachic agent, are two natural products bearing a diarylheptanoid scaffold that is incorporated into the styryl-2-pyranone moiety [3]. Preliminary biological evaluations showed that 1 and 2 feature anti-emetic activities on

• the way for their application in further biomedical investigations. Biosynthetically, katsumadain A is assumed to be derived from styryl-2-pyranone 3 and alnustone (4) [9] through a 1,6-conjugate addition/oxa-Michael addition cascade reaction (path a, Scheme 1). Indeed, both 3 and 4 are known natural

Simple synthesis of pyrrolo[3,2-e]indole-1-carbonitriles

• Adam Trawczyński,
• Robert Bujok,
• Zbigniew Wróbel and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2013, 9, 934–941, doi:10.3762/bjoc.9.107

• ), 221 (5), 220 (6), 213 (6), 193 (6), 192 (5), 165 (14), 135 (7), 108 (39), 107 (10), 105 (7), 92 (10), 91 (100); HRMS–EI (70 eV, m/z): [M]+ calcd for C23H22N4O3, 402.1692; found, 402.1684. 6-Benzyloxymethyl-3-hydroxy-7-methyl-2-((E)-styryl)-3,6-dihydropyrrolo[3,2-e]indole-1-carbonitrile (6g). Dark

Stereoselective synthesis of tetrasubstituted alkenes via a sequential carbocupration and a new sulfur–lithium exchange

• Andreas Unsinn,
• Cora Dunst and
• Paul Knochel

Beilstein J. Org. Chem. 2012, 8, 2202–2206, doi:10.3762/bjoc.8.248

• trisubstituted alkenyllithiums. Subsequent trapping with various electrophiles yields tetrasubstituted olefins with good control of the double-bond geometry (E/Z ratio up to 99:1). The novel sulfur–lithium exchange could be extended to the stereoselective preparation of Z-styryl lithium derivatives with almost

• ). Herein, we demonstrate the feasibility of this methodology and thus prepare tetrasubstituted alkenes with E/Z stereoselectivities up to 99:1. Furthermore, we show that this sulfur–lithium exchange can be extended to the stereoselective preparation of Z-styryl derivatives. Results and Discussion First, we

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• the (Me3SiO)Ph2C-group in the 2-position of the pyrrolidine ring of N-(β-styryl)pyrrolidine caused a reduction of reactivity by a factor of 30 to 60 (32a versus 32b). A reduction of nucleophilicity by three to five orders of magnitude is encountered for the enamines 32c–32e (Figure 19). The low

A concise synthesis of 3-(1-alkenyl)isoindolin-1-ones and 5-(1-alkenyl)pyrrol-2-ones by the intermolecular coupling reactions of N-acyliminium ions with unactivated olefins

• Nianhong Lu,
• Lihong Wang,
• Zhanshan Li and
• Wei Zhang

Beilstein J. Org. Chem. 2012, 8, 192–200, doi:10.3762/bjoc.8.21

• 1-alkenylboronic acid, or esters [23][24] besides allylsilane. For example, Angst reported the coupling of styrylsilanes with N-acyl-2-chloroglycine esters catalyzed by SnCl4 to give the 3-styryl glycine derivatives in 1987 [19]; Wistrand reported the coupling of methyl 1-acyl-5-methoxy-L-proline

Imidazole as a parent π-conjugated backbone in charge-transfer chromophores

• Jiří Kulhánek and
• Filip Bureš

Beilstein J. Org. Chem. 2012, 8, 25–49, doi:10.3762/bjoc.8.4

• through a thiazole-styryl π-linker (Figure 4). Whereas the series 5a–c and 7a–c showed promising optical nonlinearities, high thermal stability, excellent solubility, and good transparency, molecules 8a–d were investigated as two-photon absorbing chromophores (Table 2). Bu and co-workers also investigated

Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

• Kristina Butković,
• Željko Marinić,
• Krešimir Molčanov,
• Biserka Kojić-Prodić and
• Marija Šindler-Kulyk

Beilstein J. Org. Chem. 2011, 7, 1663–1670, doi:10.3762/bjoc.7.196

• . Illustration of intramolecular [3 + 2] cycloadditions. Styryl-sydnone 1 and stilbenyl sydnone 2 and their photoproducts F and G, respectively; target molecules 3 in this work. ORTEP of compound 14. Proposed stereochemical pathway of sydnone ring (CH–N) and trans- and cis-stilbene (α–β). Proposed stereochemical

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

• Jakub Saadi,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, 1229–1245, doi:10.3762/bjoc.6.141

• described the efficient synthesis of cyclooctanol and cyclooctenol derivatives by samarium diiodide-induced 8-endo-trig and 8-endo-dig cyclizations of γ-styryl- [20][31][33] and γ-phenylalkynyl-substituted [20][32] ketoesters. Recently, we have also reported our preliminary results on cyclizations of

• analogous starting materials bearing alkyl and aryl substituents at the styryl double bond, which furnished highly substituted cyclooctanol derivatives (Scheme 1) and in some cases compounds with cycloheptanol substructure [34]. The transformation of A to B proceeds via the samarium ketyl C followed by the

• stereochemical outcome. First, the impact on the reaction by alkyl and aryl substituents at the α-styryl carbon of the substrates will be described, then we discuss the influence of analogous β-styryl substituents. Results and Discussion Starting materials were prepared from readily available siloxycyclopropanes

Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines

• Susan Kelleher,
• Pierre-Yves Quesne and
• Paul Evans

Beilstein J. Org. Chem. 2009, 5, No. 69, doi:10.3762/bjoc.5.69

• vinyl bromide 24a in lithiation and Pd-coupling chemistry is described. In the case of the latter, hydrogenation of the styryl products afforded a single diastereoisomer. These compounds were then studied under dissolved metal reduction conditions, in which the cleavage of both N–S and C–S bonds takes

• yields of the resultant styryl adducts 27–30 were observed. It was found that employment of the boronic acids in excess (approximately 5 equiv) in conjunction with base work-up gave the desired products in good yields with no starting material 24a, or the product of bromine–hydrogen exchange 5a

A short stereoselective synthesis of (+)-(6R,2′S)-cryptocaryalactone via ring- closing metathesis

• Palakodety Radha Krishna,
• Krishnarao Lopinti and
• K. L. N. Reddy

Beilstein J. Org. Chem. 2009, 5, No. 14, doi:10.3762/bjoc.5.14

• the sub-classes of these 5,6-dihydro-2H-pyran-2-one compounds is the styryl lactones which possess a styryl moiety side chain. The styryl moiety of goniothalamin has been shown to be of importance for its cytotoxic effect on different cancer cells as well as its antimicrobial, larvicidal activity and

• anti-inflammatory activity [24]. The styryl-pyrone skeleton is often found in natural products from Equisetaceae and also from the primitive angiosperm families, such as Lauraceae, Piperaceae, Ranunculaceae and Zingiberaceae. Cryptocaryalactone 1 [25][26], kurzilactone (2) [27], goniothalamin (3) [28

• ], (+)-obolactone (4) [29] and (+)-cryptofoline (5) [30] (Figure 1) are some of the naturally occurring styryl lactones. (+)-(6R,2′S)-Cryptocaryalactone (1) first featured in the phytochemical literature when its isolation from Cryptocarya bourdilloni GAMB (Lauraceae) was reported in 1972 by Govindachari [31][32

Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• π-conjugated linkers are described. Either unsubstituted or 4-donor substituted π-linkers bearing a styryl, biphenyl, phenylethenylphenyl, and phenylethynylphenyl π-conjugated backbone are functionalized with boronic pinacol esters as well as with terminal acetylene moieties allowing their further

• enlarged π-conjugated path (Figure 1). Whereas the simplest linkers such as 4-substituted phenylboronic pinacol esters 1a–c [29] and ethynylbenzenes 2a–c [30] are well known and also commercially available, the proposed dioxaborolanes 3–6 feature styryl (series 3), biphenylyl (series 4), (E

• (Figure 1, Table 1). Results and Discussion Synthesis of boronic pinacol esters 3–6 Whilst two styryl dioxaborolanes 3a–b are known [31][32] and commercially available, the N,N-dimethylamino substituted derivative 3c needed to be synthesized. In order to achieve pure (E)-3c, at first, a hydroboration of

Microwave- assisted ring closure reactions: Synthesis of 8-substituted xanthine derivatives and related pyrimido- and diazepinopurinediones

• Joachim C. Burbiel,
• Jörg Hockemeyer and
• Christa E. Müller

Beilstein J. Org. Chem. 2006, 2, No. 20, doi:10.1186/1860-5397-2-20

• . Background Xanthine derivatives are one of the most important chemical classes of adenosine receptor antagonists [1]. High affinity and selectivity for certain adenosine receptor subtypes has been achieved by introducing substituents into the 8-position of the purine ring. Styryl substitution at this