Improving the reactivity of phenylacetylene macrocycles toward topochemical polymerization by side chains modification

• Simon Rondeau-Gagné,
• Jules Roméo Néabo,
• Maxime Daigle,
• Katy Cantin and
• Jean-François Morin

Beilstein J. Org. Chem. 2014, 10, 1613–1619, doi:10.3762/bjoc.10.167

• crystalline state to yield polydiacetylenes (PDAs) following a 1,4-addition mechanism, thus fixing the initial molecular organization through covalent bonds formation [12][13]. In order for this polymerization to proceed, the molecules within the assembly must be oriented relative to each other following

• , on the critical parameters needed for polymerization through 1,4-addition reaction [38]. In fact, the acetanilide configuration provides macrocycles which can barely self-assemble in organic solvents while the benzamide configuration yields macrocycles with much greater gelation properties that allow

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

• hydrophosphination of vinyl nitriles catalyzed by a dicationic nickel complex (Table 3). The method is based on the activation of the electrophile. It was suggested that complexation of the nitrile 50 to the chiral nickel Lewis acid activates the double bond towards 1,4-addition of the phosphine 25b. A final proton

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

• moiety, which is coupled by transmetallation with the alkyne 6 and reductive elimination to give the ynylideneindolone intermediate 11. The ynylideneindolone 11 is a vinylogous Michael system, and therefore, it is reasonable to assume a 1,4-addition of the nucleophilic enamine 12, which is employed

Regioselective 1,4-trifluoromethylation of α,β-unsaturated ketones via a S-(trifluoromethyl)diphenylsulfonium salts/copper system

• Satoshi Okusu,
• Yutaka Sugita,
• Etsuko Tokunaga and
• Norio Shibata

Beilstein J. Org. Chem. 2013, 9, 2189–2193, doi:10.3762/bjoc.9.257

• yields. Keywords: 1,4-addition; copper; fluorine; Michael addition; organo-fluorine; trifluoromethylation; Introduction One of the challenges in synthetic organic chemistry is the nucleophilic 1,4-addition of the trifluoromethyl (CF3) group into electron-deficient internal alkenes as represented by the

• Michael addition reaction, even in a racemic, non-stereoselective fashion [1][2][3][4][5]. The nucleophilic trifluoromethylation to conjugated alkenes essentially occurs solely via a 1,2-addition [1][2][3][4][5][6][7][8][9][10][11], not a 1,4-addition (Scheme 1), with the exception of non-general examples

• of regioisomers (C2/C3 1.1:1) [22]. We disclose herein the regioselective 1,4-addition of the CF3 group into simple conjugated acyclic enones including chalcones using S-(trifluoromethyl)diphenylsulfonium salt 3 and a copper system in 11–37% yields (12 examples). Results and Discussion We initiated

Gold(I)-catalyzed formation of furans from γ-acyloxyalkynyl ketones

• Marie Hoffmann,
• Solène Miaskiewicz,
• Jean-Marc Weibel,
• Patrick Pale and
• Aurélien Blanc

Beilstein J. Org. Chem. 2013, 9, 1774–1780, doi:10.3762/bjoc.9.206

• ability of gold cations to act as π or σ Lewis acids (Scheme 3) [21][55][56]. Intramolecular [1,4]-addition of the acyloxy function by oxophilic activation of γ-acyloxyalkynyl ketones could lead to the formation of gold allenolate A, which is in equilibrium with both Z or E vinylgold B and C [57

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones

• István E. Markó and
• Florian T. Schevenels

Beilstein J. Org. Chem. 2013, 9, 1319–1325, doi:10.3762/bjoc.9.148

• may indeed be operational in these cases. Protonation of diene 56 leads to the oxonium ion 57, which undergoes a 1,4-addition of another 56 unit, affording the new cation 58. At this stage, two different pathways can be followed. Either carbocation 58 can lose a proton, generating the observed triene

Establishing the concept of aza-[3 + 3] annulations using enones as a key expansion of this unified strategy in alkaloid synthesis

• Aleksey I. Gerasyuto,
• Zhi-Xiong Ma,
• Grant S. Buchanan and
• Richard P. Hsung

Beilstein J. Org. Chem. 2013, 9, 1170–1178, doi:10.3762/bjoc.9.131

• of N-1,4-addition and C-1,2-addition/β-elimination [16][17], effectively leading to a variety of nitrogen heterocyclic motifs, such as 3, which are prevalent among alkaloids (Scheme 1) [16][26][27][28][29][30][31][32]. However, there was a significant deficiency in this annulation: the inability to

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

• indanones (Scheme 4) [59]. Phenylrhodation of 1g first proceeds to form 1A. A subsequent intramolecular 1,4-hydrogen shift gives 1B, which smoothly undergoes an intramolecular 1,4-addition to yield 1C. Finally, transmetalation from the phenylzinc reagent to rhodium enolate 1C affords zinc enolate 1h, which

Radical zinc-atom-transfer-based carbozincation of haloalkynes with dialkylzincs

• Fabrice Chemla,
• Florian Dulong,
• Franck Ferreira and
• Alejandro Pérez-Luna

Beilstein J. Org. Chem. 2013, 9, 236–245, doi:10.3762/bjoc.9.28

• 1,4-addition/carbozincation of dialkylzincs or alkyl iodides based on zinc atom radical transfer, in the presence of dimethylzinc with β-(propargyloxy)enoates having pendant iodo- and bromoalkynes, is disclosed. Formation of the carbenoid intermediate is fully stereoselective at −30 °C and arises from

• prepared by iodinating (AgNO3/NIS) the terminal alkyne of enoate 3c prepared from propargyl alcohol (1c) and acrylate 2. According to our previously optimized conditions for the 1,4-addition/carbozincation reaction of dialkylzincs with β-(propargyloxy)enoates [37][38], bromoalkyne 3a was treated with Et2Zn

• intermediate formation of an alkylidene zinc carbenoid as deuterated 4aa-D was produced (Table 1, entry 2). As previously noted in the case of similar 1,4-addition/carbozincation sequences [37][38], deuterium incorporation was nearly quantitative for the Z isomer, and much lower for the E one. More

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

• Sergei Žari,
• Tiiu Kailas,
• Marina Kudrjashova,
• Mario Öeren,
• Ivar Järving,
• Toomas Tamm,
• Margus Lopp and
• Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

• yields (up to 99%) and in high enantioselectivities (up to 93%). This enantioselective 1,4-addition to unsaturated 1,4-diketones affords valuable intermediates for further synthetic transformations. The conjugated addition to unsaturated 1,4-diketone 1. Organocatalysts screened. Proposed transition state

Novel fatty acid methyl esters from the actinomycete Micromonospora aurantiaca

• Jeroen S. Dickschat,
• Hilke Bruns and
• Ramona Riclea

Beilstein J. Org. Chem. 2011, 7, 1697–1712, doi:10.3762/bjoc.7.200

• − 57]+ ion, which is typical for anteiso-FAMEs. The synthesis of methyl 8-methyldecanoate (95) as a reference compound was started from 1-bromo-2-methylbutane (117b, Scheme 3). Copper-catalysed 1,4-addition of the respective Grignard reagent to methyl acrylate in the presence of trimethylchlorosilane

• , dimethyl sulfide, and 4-dimethylaminopyridine gave methyl 5-methylheptanoate (118b). A sequence of LiAlH4 reduction to the alcohol 119b, conversion into the bromide 120b, and Cu-mediated 1,4-addition of the Grignard reagent to methyl acrylate furnished the desired FAME 95. Its mass spectrum and retention

• bromination of 2-methylpentan-1-ol (125) and subsequent Cu-catalysed 1,4-addition of the respective Grignard reagent to methyl acrylate, resulting in methyl 5-methyloctanoate (127, Scheme 4). Reduction to the aldehyde 129 via the alcohol 128, addition of methylmagnesium bromide, and bromination resulted in

One-pot gold-catalyzed synthesis of 3-silylethynyl indoles from unprotected o-alkynylanilines

• Jonathan P. Brand,
• Clara Chevalley and
• Jérôme Waser

Beilstein J. Org. Chem. 2011, 7, 565–569, doi:10.3762/bjoc.7.65

• -alkynylanilines can be followed by 1,4-addition to enones [15][16], iodination [17] or reaction with 1,3-dicarbonyl compounds [18]. Perumal recently demonstrated that aldehydes and nitroalkenes can be used as electrophilic partners [19][20]. Triple bonds can also serve as a second electrophile for the

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• solve these issues. The Friedel–Crafts-type 1,4-addition of arenes to unsaturated carbonyl compounds and their derivatives can be considered as Michael reactions. They have been extensively reviewed elsewhere and will be not discussed in this chapter [52][53][54][55]. For the synthesis of 1,1

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• [3]. It was shown that an attack of phenylmagnesium chloride or phenyl sodium after 1,4-addition leads to the 6-substituted benzanthrone derivative 3 (Scheme 1). On changing the solvent from ether-benzene to tetrahydrofuran the ketone could also be isolated in high yields, but additionally a labile

• monitored by 1H NMR spectroscopy (Figure 1) in CDCl3. This conversion is much slower when the CDCl3 is filtered through an alumina plug before use. The reaction constitutes a formal dehydrogenation of 4 (Scheme 2). As shown in Scheme 2, we propose that the formation of 4 and 7 starts as a 1,4-addition

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• intermediate 29 was obtained in two steps starting from compound (−)-21 (Scheme 6), via 1,4-addition of potassium cyanide followed by protection of the ketone as the ethylene ketal. Alkylation of the carbanion of nitrile 28 with iodide 27 provided exclusively diastereoisomer 29. Stepwise reduction (DIBAL and

• bridgehead carboxy derivatives more closely resembling 1 centered on the preparation of nitrile analog 103 (Scheme 17). It was anticipated that the cyano group could be easily introduced by 1,4-addition of cyanide ion to 99 and later converted into a carboxylic acid at an appropriate time. To this end

• , treatment of substrate 94 with TBSCl in the presence of imidazole and a catalytic amount of DMAP provided 99. The Nagata reagent [49] readily transformed 99 into 100, presumably by 1,4-addition of cyanide ion and ensuing elimination of methanol. Unexpectedly, enone 100 was immune to the one-pot enol

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• G. K. Surya Prakash Xiaoming Zhao Sujith Chacko Fang Wang Habiba Vaghoo George A. Olah Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, Los Angeles, California 90089-1661 10.3762/bjoc.4.17 Abstract The 1,4-addition of a monofluoromethyl

• " nucleophiles that readily undergo 1,2-addition with Michael type acceptors instead of 1,4-addition [14][15][16]. Different strategies have been employed to achieve 1,4-addition, which is still percieved to be a challenge. For instance, Yamamoto [17] and Röschenthaler [18][19] have made use of bulky aluminum

• Lewis acids to protect the carbonyl of Michael acceptors and thus sucessfully transferred the trifluoromethyl anion generated from the "Ruppert-Prakash reagent" (TMS-CF3) in a 1,4-manner rather than the favored 1,2-addition. Portella et al. [20] have shown that 1,4-addition of difluoroenoxysilanes to

Multiple hydride reduction pathways in isoflavonoids

• Auli K. Salakka,
• Tuija H. Jokela and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2006, 2, No. 16, doi:10.1186/1860-5397-2-16

• (Table 2), [16][25][26][27][28]except with hydroxy substituted substrates which do not react at all. Apparently the first step involves a 1,4-addition to give the isoflavanone enolate which picks up a proton from the solvent and is reduced further to the saturated alcohol. There are no reports of the

• ). We have discussed a possible mechanism to explain these hydroxyl-dependent divergent pathways [43]. To summarize, all hydride addition reactions with isoflavones appear to involve an initial 1,4-addition to give the isoflavanone enolate. In a hydroxylic solvent, or even on workup under basic

• conditions, the ketone is generated, and reduced further to the saturated alcohol (NaBH4). In a nonprotic solvent, the β-aryloxyenolate will undergo a retro-Michael addition, giving the phenolate anion of the ring opened 2-propen-1-one which may undergo a 1,2- or 1,4-addition of hydride (LiAlH4, LiBH4). If

A convenient synthesis of γ-functionalized cyclopentenones

• Nour Lahmar,
• Taïcir Ben Ayed,
• Moncef Bellassoued and
• Hassen Amri

Beilstein J. Org. Chem. 2005, 1, No. 11, doi:10.1186/1860-5397-1-11

• previously reported, the 1,4-addition of primary nitroalkanes [7][8][9][10][11][12] to functionalized α,β-unsaturated ketones was considered as an appropriate method to prepare multifunctional nitroketonic compounds. These intermediates are important in organic synthesis because the nitro group can be