- Wadsworth-Emmons reaction: The unique catalytic reaction by a solid base
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The near-stoichiometric amount of bases is used both in laboratory and industry in Wadsworth-Emmons (WE) reactions, since the by-product, (EtO) 2P(O)OH, formed in the reaction neutralizes the base into an inert salt. A strategy to design, develop, and evolve the recyclable Mg-Al-hydrotalcite-OtBu (HT-OtBu) by the interaction of KOtBu with the calcined hydrotalcite that transforms a well-defined stoichiometric WE reaction into a catalytic one in an effort to minimize the quantum of effluents released and reduce the cost of the process is described here. HT-OtBu is found to be an efficient solid base for WE reactions for the simple synthesis of α,β-unsaturated esters and nitriles for the first time. The HT-OtBu, composed of various ratios of Mg/Al (i.e., 2, 2.5, and 3) and different contents of tBuO - (Mg/Al:3), and their precursors were prepared and well characterized to draw a correlation between structure and reactivity of the hydrotalcites in WE reactions.
- Choudary, Boyapati M.,Kantam, Mannepalli L.,Reddy, Chinta Reddy V.,Bharathi, Balagam,Figueras, Francois
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Read Online
- Palladium-catalyzed synthesis of nitriles from N-phthaloyl hydrazones
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The Pd-catalyzed transformation of N-phthaloyl hydrazones into nitriles involving the cleavage of an N-N bond is reported. The use of N-heterocyclic carbene as a ligand is essential for the success of the reaction. N-Phthaloyl hydrazones prepared from aromatic aldehydes or cyclobutanones are applicable to this transformation, which gives aryl or alkenyl nitriles, respectively.
- Ano, Yusuke,Higashino, Masaya,Yamada, Yuki,Chatani, Naoto
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p. 3799 - 3802
(2022/04/07)
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- Sulfur-controlled and rhodium-catalyzed formal (3 + 3) transannulation of thioacyl carbenes with alk-2-enals and mechanistic insights
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A rhodium-catalyzed denitrogenative formal (3 + 3) transannulation of 1,2,3-thiadiazoles with alk-2-enals is achieved, producing 2,3-dihydrothiopyran-4-ones in moderate to excellent yields. An inverse KIE of 0.49 is obtained, suggesting the reversibility of the oxidative addition of thioacyl Rh(i) carbenes to alk-2-enals. The late-stage structural modifications of steroid compounds are realized. Moreover, our studies show that thioacyl carbenes have different reactivities to those of α-oxo and α-imino carbenes, and highlight the importance of heteroatoms in deciding the reactivities of heterovinyl carbenes.
- Wu, Qiuyue,Dong, Ziyang,Xu, Jiaxi,Yang, Zhanhui
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supporting information
p. 3173 - 3180
(2021/04/21)
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- Heteroleptic Copper-Based Complexes for Energy-Transfer Processes: E → Z Isomerization and Tandem Photocatalytic Sequences
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Energy-transfer processes involving copper complexes are rare. Using an optimized heteroleptic copper complex, Cu(bphen)(XantPhos)BF4, photosensitized E → Z isomerization of olefins is demonstrated. The XantPhos ligand afforded sensitizers with improved catalyst stability, while the bphen ligand lengthened the excited-state lifetime. A series of 25 di- and trisubstituted alkenes underwent photoisomerization, including macrocycles and 1,3-enynes. Cu(bphen)(XantPhos)BF4 could also be employed in a tandem ATRA/photoisomerization process employing arylsulfonyl chlorides, an example of photoisomerization with halide-substituted olefins.
- Cruché, Corentin,Neiderer, William,Collins, Shawn K.
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p. 8829 - 8836
(2021/07/28)
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- Copper-Photocatalyzed Contra-Thermodynamic Isomerization of Polarized Alkenes
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The contra-thermodynamic isomerization of α- and β-substituted cinnamate derivatives catalyzed by the Cu(OAc)2/rac-BINAP complex under blue light irradiation is reported. The use of an oxazolidinone template, which favored the complexation of the copper catalyst to the substrate, allowed the E → Z isomerization of the catalytically formed chromophore under simple and robust reaction conditions in good to excellent ratios. The mechanism of this process based on the transient formation of a chromophore was also studied.
- Bouillon, Jean-Philippe,Brégent, Thibaud,Poisson, Thomas
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p. 7688 - 7693
(2020/10/09)
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- Amination of Carbenium Ions Generated by Directed Protonolysis of Cyclopropane
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Directed intramolecular protonolyis of the cyclopropane C-C bond is demonstrated as a strategy to generate carbenium ions. This intermediate can be subjected to amination with nitriles under Ritter reaction conditions. Directing groups such as carbamate, carboxamide, urea, ester, and ketone were found to be efficient for regioselective anti-Markovnikov cleavage of cyclopropane. Depending on the directing group, the amination provided orthogonally protected 1,4-diamine, ?-amino carboxylic, and ?-amino ketone derivatives.
- Skvorcova, Marija,Lukasevics, Lukass T.,Jirgensons, Aigars
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p. 3780 - 3792
(2019/03/29)
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- Metal-Free Direct C?H Cyanation of Alkenes
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A metal-free and direct alkene C?H cyanation is described. Directing groups are not required and the mechanism involves electrophilic activation of the alkene by a cyano iodine(III) species generated in situ from a [bis(trifluoroacetoxy)iodo]arene and tri
- Wang, Xi,Studer, Armido
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supporting information
p. 11792 - 11796
(2018/09/10)
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- Covalent Immobilization of (?)-Riboflavin on Polymer Functionalized Silica Particles: Application in the Photocatalytic E→Z Isomerization of Polarized Alkenes
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The covalent immobilization of the biomimetic, photo-organocatalyst (?)-riboflavin on silica micro- and nanoparticles via atom transfer radical polymerization (ATRP) is disclosed. Given the effectiveness of (?)-riboflavin as a versatile, environmentally benign photocatalyst, an immobilization strategy based on acrylate-linker modification of the catalyst core and controlled polymerization on initiator pre-functionalized silica particles has been developed. Validation of this approach is demonstrated in the E→Z isomerization of a benchmark cinnamonitrile (Z/E up to 88:12) with 0.97 mol % catalyst loading. Characterization of the immobilized photocatalyst supports covalent embedding of the catalyst in the polymeric brushes on the silica particle surface.
- Metternich, Jan B.,Sagebiel, Sven,Lückener, Anne,Lamping, Sebastian,Ravoo, Bart Jan,Gilmour, Ryan
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supporting information
p. 4228 - 4233
(2018/03/21)
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- Cyclization of Ketones with Nitriles under Base: A General and Economical Synthesis of Pyrimidines
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A facile, general, and economical synthesis of diversely functionalized pyrimidines has been realized under basic conditions via the copper-catalyzed cyclization of ketones with nitriles. The reaction proceeds via a novel pathway involving the nitriles ac
- Su, Lebin,Sun, Kang,Pan, Neng,Liu, Long,Sun, Mengli,Dong, Jianyu,Zhou, Yongbo,Yin, Shuang-Feng
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supporting information
p. 3399 - 3402
(2018/06/11)
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- Photocatalytic E → Z isomerization of polarized alkenes inspired by the visual cycle: Mechanistic dichotomy and origin of selectivity
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Iteratively executed with exquisite spatial and temporal control, the selective isomerization of polarized alkenes underpins a plethora of complex biological processes ranging from natural product biosynthesis through to the mammalian visual cycle. However, nature's proficiency conceals the inherent difficulties in replicating this contrathermodynamic transformation in the laboratory. Recently, we disclosed the first highly Z-selective isomerization of polarized alkenes, employing the cinnamoyl chromophore as a retinal surrogate under UV-irradiation (402 nm) with (-)-riboflavin (Vitamin B2) as an inexpensive, organic photocatalyst (J. Am. Chem. Soc. 2015, 137, 11254-11257). This study was inspired by the propensity of crystalline (-)-riboflavin in the eyes of vertebrates to invert the intrinsic directionality of retinal isomerization. Herein, we extend this methodology to include a bioinspired, catalytic E → Z isomerization of α,β-unsaturated nitriles, thereby mimicking the intermediate Opsin-derived, protonated Schiff base in the visual cycle with simple polarized alkenes. Replacement of the iminium motif by a cyano group is well tolerated and gives an additional degree of versatility for postisomerization functionalization. Broad substrate scope is demonstrated (up to 99:1 Z:E) together with evidence of mechanistic dichotomy via both singlet and triplet energy transfer mechanisms. Kinetic studies, temperature dependent photostationary state correlations and investigation of substituent-based electronic perturbation of the alkene identified polarization combined with increased Z-isomer activation barriers as the selectivity governing factors in catalysis. This investigation demonstrates the importance of internal structural preorganization on photostationary composition and explicates the augmented Z-selectivity upon hydrogen-alkyl exchange at the β-position of the alkene.
- Metternich, Jan B.,Artiukhin, Denis G.,Holland, Mareike C.,Von Bremen-Kuhne, Maximilian,Neugebauer, Johannes,Gilmour, Ryan
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p. 9955 - 9977
(2018/05/31)
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- A Catalytic Peterson-like Synthesis of Alkenyl Nitriles
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A heterogeneous fluoride catalyst was found to enable the straightforward formation of alkenyl nitriles from the reaction of aldehydes and simple or substituted acetonitriles, in the presence of commercially available silazanes and in solvent-free conditions. The protocol afforded the products in good to excellent yields with selectivity values dependent on the nature of the substrates. It represents an alternative to classic approaches using stoichiometric strong bases, and the catalyst can be easily recovered and reused for consecutive cycles.
- Lanari, Daniela,Alonzi, Matteo,Ferlin, Francesco,Santoro, Stefano,Vaccaro, Luigi
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supporting information
p. 2680 - 2683
(2016/06/15)
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- Cascade reaction of propargylic alcohols with hydroxylamine hydrochloride: facile synthesis of α,β-unsaturated oximes and nitriles
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We have developed an easy and practical method for the synthesis of α,β-unsaturated oximes and nitriles from readily available propargylic alcohols with hydroxylamine hydrochloride (NH2OH·HCl) under metal-free conditions. By using or not using p-toluenesulfonyl chloride (p-TsCl) as the dehydrating promoter, the desired nitriles or oximes could be obtained, respectively via a three-step one-pot or two-step one-pot process in moderate to excellent yields with good functional group compatibility.
- Zhang, Qi,Zhang, Linjing,Tang, Chaojun,Luo, Huan,Cai, Xuediao,Chai, Yonghai
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p. 6935 - 6942
(2016/10/14)
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- COMPOUNDS AND METHODS OF TREATING OCULAR DISORDERS
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A method of treating an ocular disorder in a subject associated with increased all-trans-retinal in an ocular tissue includes administering to the subject a therapeutically effective amount of a primary amine compound of formula (I); and pharmaceutically acceptable salts thereof.
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Paragraph 00221
(2016/06/14)
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- Highly efficient Rh-catalyzed asymmetric hydrogenation of α,β-unsaturated nitriles
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A highly efficient enantioselective hydrogenation of α,β-unsaturated nitriles catalyzed by Rh-(R,R)-f-spiroPhos complex has been developed. With Rh-(R,R)-f-spiroPhos catalyst and under mild conditions, a wide range of α,β-unsaturated nitriles including the (E)- and (Z)-isomers of 3-alkyl-3-aryl, 3,3-diaryl, and 3,3-dialkyl α,β-unsaturated nitriles were hydrogenated to the corresponding chiral nitriles with excellent enantioselectivities (up to 99.9% ee) and high turnover numbers (TON up to 10,000).
- Yan, Qiaozhi,Kong, Duanyang,Li, Meina,Hou, Guohua,Zi, Guofu
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supporting information
p. 10177 - 10181
(2015/09/01)
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- Expansion of first-in-class drug candidates that sequester toxic all-trans-retinal and prevent light-induced retinal degeneration
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All-trans-retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all-trans-retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11-cis-retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all-trans-retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all-trans-retinyl ester into 11-cis-retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation.
- Zhang, Jianye,Dong, Zhiqian,Mundla, Sreenivasa Reddy,Hu, X. Eric,Seibel, William,Papoian, Ruben,Palczewski, Krzysztof,Golczak, Marcin
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supporting information
p. 477 - 491
(2015/01/30)
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- Palladium-Catalyzed α,β-Dehydrogenation of Esters and Nitriles
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A highly practical and general palladium-catalyzed methodology for the α,β-dehydrogenation of esters and nitriles is reported. Generation of a zinc enolate or (cyanoalkyl)zinc species followed by the addition of an allyl oxidant and a palladium catalyst results in synthetically useful yields of α,β-unsaturated esters, lactones, and nitriles. Preliminary mechanistic investigations are consistent with reversible β-hydride elimination and turnover-limiting, propene-forming reductive elimination.
- Chen, Yifeng,Romaire, Justin P.,Newhouse, Timothy R.
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p. 5875 - 5878
(2015/05/27)
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- Lewis Acid Mediated Tandem Reaction of Propargylic Alcohols with Hydroxylamine Hydrochloride to Give α,β-Unsaturated Amides and Alkenyl Nitriles
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We have developed a highly selective method for the synthesis of α,β-unsaturated amides and alkenyl nitriles from readily available propargylic alcohols. The reaction proceeded smoothly under the neutral conditions with hydroxylamine hydrochloride (NH2OH·HCl) as the nitrogen source. The development of these new strategies has significantly extended the application of hydroxylamine hydrochloride to the chemistry of propargylic alcohols. Moreover, both secondary and tertiary alcohols have been highly regioselectively transformed to the desired products with good functional group compatibility.
- Han, Ya-Ping,Song, Xian-Rong,Qiu, Yi-Feng,Hao, Xin-Hua,Wang, Jia,Wu, Xin-Xing,Liu, Xue-Yuan,Liang, Yong-Min
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p. 9200 - 9207
(2015/09/28)
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- Asymmetric hydrogenation of α,β-unsaturated nitriles with base-activated iridium N,P ligand complexes
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Although many chiral catalysts are known that allow highly enantioselective hydrogenation of a wide range of olefins, no suitable catalysts for the asymmetric hydrogenation of α,β-unsaturated nitriles have been reported so far. We have found that Ir N,P ligand complexes, which under normal conditions do not show any reactivity towards α,β-unsaturated nitriles, become highly active catalysts upon addition of N,N- diisopropylethylamine. The base-activated catalysts enable conjugate reduction of α,β-unsaturated nitriles with H2 at low catalyst loadings, affording the corresponding saturated nitriles with high conversion and excellent enantioselectivity. In contrast, alkenes lacking a conjugated cyano group do not react under these conditions, making it possible to selectively reduce the conjugated C=C bond of an α,β-unsaturated nitrile, while leaving other types of C=C bonds in the molecule intact.
- Mueller, Marc-Andre,Pfaltz, Andreas
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supporting information
p. 8668 - 8671
(2014/08/18)
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- Bronsted acid mediated nitrogenation of propargylic alcohols: An efficient approach to alkenyl nitriles
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A novel and efficient approach to alkenyl nitriles from readily available propargylic alcohols has been developed. This nitrogenation reaction is transition-metal-free and could be conducted under air at ambient temperature, which makes this protocol promising and practical. Moreover, NH4Br is disclosed as an efficient additive to promote the stereoselectivity of this reaction. the Partner Organisations 2014.
- Huang, Xiaoqiang,Jiao, Ning
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supporting information
p. 4324 - 4328
(2014/06/23)
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- Synthesis and applications of quaternized highly branched polyacrylamide as a novel multi-site polymeric phase transfer catalyst
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In current study, quaternized highly branched polyacrylamide (HBAA) was synthesized and used as an efficient multi-site polymeric phase transfer catalyst in nucleophilic substitution reactions and also in synthesis of α, β-unsaturated nitriles from reaction of acetonitrile and carbonyl compounds. The quaternized HBAA was synthesized via two steps. First, HBAA was synthesized via self-condensing vinyl polymerization of acrylamide at appropriate molar ratio of monomer to diperiodatocuprate(III). In the second step, 3-acrylamidopropyl trimethylammonium iodide was polymerized on peripheral area of the HBAA in the presence of diperiodatocuprate(III) solution again. The thermal behavior of HBAA and that of the quaternized HBAA were studied by DSC and TGA analysis. This phase transfer catalyst was easily recovered after reaction and reused several times without any loss of activity.
- Mahdavi, Hossein,Amirsadeghi, Mehdi
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p. 791 - 797
(2013/07/27)
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- Selective reactivity of electron-rich aryl iodides in the Heck arylation of disubstituted alkenes catalyzed by palladium-arylurea complexes
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A catalyst consisting of 1 mol % of the 1:2 complex of Pd(OAc)2 with N-(4-carbethoxyphenyl)urea promotes the Heck arylation of 2- or 3-substituted, conjugated esters, nitriles, aldehydes, and ketones (an uncharacteristically broad range of substrates), but only with electron-rich aryl iodides (an uncharacteristically narrow range of halides).
- Smith, Matthew R.,Jang, Young Jin,Kim, Jung Yun,Ciufolini, Marco A.
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p. 10139 - 10151
(2013/11/06)
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- Nucleophilic addition of α-(dimethylsilyl)nitriles to aldehydes and ketones
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α-Alkylated (dimethylsilyl)acetonitriles (Me2HSiCR 3R4CN) react spontaneously with aldehydes in DMSO to give β-hydroxynitriles in good to high yields. The addition to ketones is effectively promoted by using MgCl2/su
- Jinzaki, Takaaki,Arakawa, Mitsuru,Kinoshita, Hidenori,Ichikawa, Junji,Miura, Katsukiyo
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supporting information
p. 3750 - 3753
(2013/08/23)
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- Synthesis of homotaurine and 1-substituted homotaurines from α,β-unsaturated nitriles
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Homotaurine and a series of 1-substituted homotaurines were readily synthesized in satisfactory to good yields via the Michael addition of thioacetic acid to aliphatic and aromatic α,β-unsaturated nitriles followed by lithium aluminum hydride mediated reduction and performic acid oxidation. The synthesis of 1,1-disubstituted homotaurines was attempted with β,β-disubstituted acrylonitriles as starting materials but failed due to steric hindrance. The current process is an efficient method for the synthesis of 1-substituted homotaurines. Georg Thieme Verlag Stuttgart New York.
- Ma, Yunhai,Xu, Jiaxi
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experimental part
p. 2225 - 2230
(2012/09/22)
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- Synthesis of acrylonitriles through an FeCl3-catalyzed domino propargylic substitution/aza-Meyer-Schuster rearrangement sequence
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Nontoxic cyanide source: An unprecedented route to acrylonitriles by employing propargylic alcohols and para-tolylsulfonohydrazide as a combined cyano source has been developed (see scheme). This efficient and practical cyanation reaction proceeds through an FeCl3-catalyzed domino propargylic substitution/aza-Meyer-Schuster rearrangement sequence, the rearrangement process of which is reported for the first time. Copyright
- Hao, Lu,Wu, Feng,Ding, Zong-Cang,Xu, Su-Xia,Ma, Yan-Li,Chen, Li,Zhan, Zhuang-Ping
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supporting information; experimental part
p. 6453 - 6456
(2012/06/15)
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- 5, 7-SUBSTITUTED-IMIDAZO [1, 2-C] PYRIMIDINES AS INHIBITORS OF JAK KINASES
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Compounds of Formula I: (Formula should be inserted here) and stereoisomers and pharmaceutically acceptable salts and solvates thereof in which R1, R2, R3, R4, R5, R6, R7, X1 and X2 have the meanings given in the specification, are inhibitors of one or more JAK kinases and are useful in the treatment of autoimmune diseases, inflammatory diseases, rejection of transplanted organs, tissues and cells, as well as hematologic disorders and malignancies and their co-morbidities.
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Page/Page column 80
(2011/11/01)
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- Direct oxidative coupling of benzenes with acrylonitriles to cinnamonitriles catalyzed by Pd(OAc)2/HPMoV/O2 system
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A facile direct synthesis of cinnamonitriles from acrylonitriles and benzenes is successfully achieved by using Pd(OAc)2/HPMoV/O 2 catalyst system via the direct C-H bond activation of benzenes using molecular oxygen as a terminal oxidant.
- Obora, Yasushi,Okabe, Yoshihisa,Ishii, Yasutaka
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supporting information; experimental part
p. 4071 - 4073
(2010/11/04)
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- P[N(i-Bu)CH2CH2]3N: Nonionic Lewis base for promoting the room-temperature synthesis of α,β-unsaturated esters, fluorides, ketones, and nitriles using Wadsworth - Emmons phosphonates
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The bicyclic triaminophosphine P(RNCH2CH2) 3N (R = i-Bu, 1c) serves as an effective promoter for the room-temperature stereoselective synthesis of α,β-unsaturated esters, fluorides, and nitriles from a wide array of aromatic, aliphatic, heterocyclic, and cyclic aldehydes and ketones, using a range of Wadsworth-Emmons (WE) phosphonates. Among the analogues of 1c [R = Me (1a), i-Pr (1b), Bn (1d)], 1a and 1b performed well, although longer reaction times were involved, and 1d led to poorer yields than 1c. Functionalities such as cyano, chloro, bromo, methoxy, amino, ester, and nitro were well tolerated. We were able to isolate and characterize (by X-ray means; see above) the reactive WE intermediate species formed from 2b and 1c.
- Chintareddy, Venkat Reddy,Ellern, Arkady,Verkade, John G.
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supporting information; experimental part
p. 7166 - 7174
(2010/12/25)
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- Iron-facilitated direct oxidative C-H transformation of allylarenes or alkenes to alkenyl nitriles
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This paper describes the first direct approach to alkenyl nitriles from allylarenes or alkenes facilitated by an inexpensive homogeneous iron catalyst. Three C-H bond cleavages occur under the mild conditions during this process. Mechanistic studies indic
- Qin, Chong,Jiao, Ning
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supporting information; experimental part
p. 15893 - 15895
(2011/01/03)
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- Δ2-isoxazolines from arylcyclopropanes: III. Phenylcyclopropanes substituted in three-membered ring in reaction with nitrosyl chloride activated with oxides of sulfur(IV, VI)
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The reaction of phenylcyclopropanes substituted in the three-membered ring with nitrosyl chloride activated with sulfur(IV, VI) oxides provided in good yield substituted 5-phenylisoxazolines as a mixture of structural isomers.
- Bondarenko,Gavrilova,Saginova,Zyk,Zefirov
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experimental part
p. 218 - 225
(2009/09/25)
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- An efficient one-pot synthesis of tethered cyclohexadiene enaminonitriles from methyl-ketones: An effective route to quinazolines
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The quinazolines represent a useful natural product scaffold with demonstrated activities against disorders such as high blood pressure and benign prostatic hyperplasia. Here we report on the synthesis and biological activity of a series of quinazolines t
- Bench, Bennie J.,Suarez, Victor H.,Watanabe, Coran M.H.
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p. 3126 - 3130
(2008/12/22)
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- Synthetic application of intramolecular cyanoboration on the basis of removal and conversion of a tethering group by palladium-catalyzed retro-allylation
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A new synthetic strategy, involving utilization of a tethered intramolecular reaction with a removable tether, was demonstrated by the intramolecular cyanoboration-retro-allylation sequence. Georg Thieme Verlag Stuttgart.
- Ohmura, Toshimichi,Awano, Tomotsugu,Suginome, Michinori,Yorimitsu, Hideki,Oshima, Koichiro
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p. 423 - 427
(2008/09/17)
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- Highly enantioselective conjugate reduction of β,β-disubstituted α,β-unsaturated nitriles
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(Chemical Equation Presented) Easy access: The highly enantioselective conjugate reduction of α,β-unsaturated nitriles is achieved by employing bench-top stable copper(II) acetate and josiphos (L) as the ligand in the presence of polymethylhydrosiloxane (
- Lee, Daehyung,Kim, Daesung,Yun, Jaesook
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p. 2785 - 2787
(2008/02/04)
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- Phosphazene base-catalyzed condensation of trimethylsilylacetate with carbonyl compounds
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The t-Bu-P4 base was found to be an excellent catalyst for the condensation of trimethylsilylacetate or trimethylacetonitrile with carbonyl compounds to form functionalized alkenes and β-enaminoesters were also synthesized by the condensation with formanilides. The Royal Society of Chemistry 2006.
- Kobayashi, Koji,Ueno, Masahiro,Kondo, Yoshinori
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p. 3128 - 3130
(2008/09/20)
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- Borrowing hydrogen: Indirect "Wittig" olefination for the formation of C-C bonds from alcohols
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The successful development of an indirect three-step domino sequence for the formation of C-C bonds from alcohol substrates is described. An iridium-catalysed dehydrogenation of alcohol 1 affords the intermediate aldehyde 2. The desired C-C bond can then be formed by a facile Wittig olefination, yielding the intermediate alkene 3. In the final step the alkene is hydrogenated to afford the indirect Wittig product, the alkane 4. The key to this process is the concept of borrowing hydrogen; hydrogen removed in the initial dehydrogenation step is simply borrowed by the iridium catalyst. Functioning as a hydrogen reservoir, the catalyst facilitates C-C bond formation before subsequently returning the borrowed hydrogen in the final step. Herein we present full details of our examination into both the substrate and reaction scope and the limitations of the catalytic cycle. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Black, Phillip J.,Edwards, Michael G.,Williams, Jonathan M. J.
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p. 4367 - 4378
(2007/10/03)
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- A new alternative to Stryker's reagent in hydrosilylation: Synthesis, structure, and reactivity of a well-defined carbene-copper(II) acetate complex
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A new, air stable and well-defined carbene-copper(II) complex has been prepared, which is an efficient precatalyst for the 1,2- and 1,4-reduction of carbonyl compounds under hydrosilylation conditions. The Royal Society of Chemistry 2005.
- Yun, Jaesook,Kim, Daesung,Yun, Hoseop
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p. 5181 - 5183
(2007/10/03)
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- Palladium-catalyzed transformation of cyclobutanone O-benzoyloximes to nitriles via C-C bond cleavage
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Palladium-catalyzed transformation of cyclobutanone O-benzoyloximes to a variety of nitriles is described. The reaction may proceed via two important steps, that is, (i) oxidative addition of the N-O bond of oximes to Pd(0) to give a cyclobutylideneaminopalladium(II) species and (ii) β-carbon elimination of this species to afford a reactive alkylpalladium species. The kind of products is very dependent on the nature of substituents on the cyclobutane ring. The direction of the C-C bond cleavage is controlled by the kind of ligand employed. The sequential reaction composed of the C-C bond cleavage and the subsequent intra- and intermolecular C-C bond formations via the corresponding alkylpalladium species is also demonstrated. For example, an oxime having an alkynyl moiety at a suitable position reacts with a variety of alkenes to afford nitriles bearing dienylcyclopentane moiety in moderate to good yields.
- Nishimura, Takahiro,Nishiguchi, Yoshiki,Maeda, Yasunari,Uemura, Sakae
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p. 5342 - 5347
(2007/10/03)
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- Catalytic electronic activation: Indirect "Wittig" reaction of alcohols
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Hydrogen atoms are borrowed during the in situ oxidation of the starting alcohol to the corresponding aldehyde and are subsequently returned in the hydrogenation of the alkene intermediate, which is formed by Wittig olefination of the aldehyde. This proce
- Edwards, Michael G.,Williams, Jonathan M.J.
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p. 4740 - 4743
(2007/10/03)
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- Zinc(II) promoted conversion of aryltriazenes to aryl iodides and aryl nitriles
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Aryltriazenes react with zinc perchlorate/zinc cyanide to produces arylnitriles and react with zinc iodide to produce aryliodides. The reaction mechanism involves aryl radicals that have been trapped by addition to propenenitriles in a good preparative Meerwein arylation process.
- Patrick, Timothy B.,Juehne, Thomas,Reeb, Elmer,Hennessy, Daniel
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p. 3553 - 3554
(2007/10/03)
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- Stereoselective synthesis of 3-alkylcinnamonitriles
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Stereoselective synthesis of (2Z)-3-arylselenocinnamonitriles and coupling them with Grignard reagents catalysized by CuI, giving the trisubstituted alkenes with main retention products.
- Zhao, Chang-Qiu,Huang, Xian
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p. 3607 - 3611
(2007/10/03)
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- Synthesis and histamine H2 agonistic activity of arpromidine analogues: replacement of the pheniramine-like moiety by non-heterocyclic groups
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Analogues of the potent histamine H2 agonist arpromidine, characterized by non-hetrocyclic groups (phenyl, cyclohexyl, alkyl) instead of the pheniramine-like portion, were prepared and tested for their H2 agonistic and H1 antagonistic activity in the isolated guiea pig right atrium and ileum, respectively.In the diphenylpropylguanidine series an increase in H2 agonistic potency resulted from mono- or difluorination at one or both phenyl rings in the meta and/or para position (pD2 7.75 vs pD2 = 7.15 for the unsubstituted parent compound).Compounds chlorinated atboth phenyl rings were considerably less potent.Highest combined H2 agonistic/H1 antagonistic potency was found in the 4-fluorophenyl series.The arpromidine analogue with cyclohexyl and methyl group instead of phenyl and pyridine ring proved to be 30 times more potent than histamine in the atrium.The H1 antagonistic potency in cyclohexyl compounds was lower than in the diaryl series.Thus, aromatic rings appear not to be required for high H2 agonistic potency but are useful for combined H2 agonistic/H1 antagonistic activity. histamine / H2 receptor / H2 agonist / arpromidine / impromidine / H1 antagonist / antihistamine
- Buschauer, A,Friese-Kimmel A,Baumann, G,Schunack, W
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p. 321 - 330
(2007/10/02)
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- A New Version of the Peterson Olefination Using Bis(trimethylsilyl)methyl Derivatives and Fluoride Ion as Catalyst
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Reaction between a variety of bis(trimethylsilyl)methyl derivatives and carbonyl compounds under fluoride ion as catalyst is described.The reaction works especially well with nonenolizable carbonyl compounds to give the expected alkenes in high yields and, in some cases, with high stereoselectivity.Application of this methodology to an intramolecular alkenation providing a tricyclic benzocarbacephem ring system is also described.
- Palomo, Claudio,Aizpurua, Jesus M.,Garcia, Jesus M.,Ganboa, Inaki,Cossio, F. P.,et al.
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p. 2498 - 2503
(2007/10/02)
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- Reactions of Arylazoxy Aryl Sulfones with α,β-Unsaturated Esters and Nitriles in the Presence of a Palladium(0) Catalyst
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The reactions of arylazoxy aryl sulfones (1) with α,β-unsaturated esters and nitriles in the presence of a palladium(0) catalyst were found to give aryl-substituted esters and nitriles in good yield.
- Kamigata, Nobumasa,Satoh, Mayumi,Fukushima, Takamasa
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p. 2118 - 2120
(2007/10/02)
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- TWO CONVENIENT SYNTHESES OF 2-ARYL-1-CYANO-1-PROPENES FROM QUATERNARY AMMONIUM SALTS
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Two readily available and different quaternary ammonium salts have been prepared by the alkylation of vinamidinium salt reduction products.These salts have been successfully converted to 2-aryl-1-cyano-1-propenes and this methodology represents a clean an
- Gupton, John T.,Zembower, David,Miller, John
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p. 1891 - 1903
(2007/10/02)
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- Reaction of α-Substituted β-Bromostyrenes with Dicarbonyldicyanonickelate(0) Anion in Alkaline Medium under Carbon Monoxide
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The reactions of (E)- and (Z)-β-bromostyrene (1a) with dicarbonyldicyanonickelate(0) anion generated in situ in the presence of sodium or calcium hydroxide under carbon monoxide gave a carbonylated product mixture of (E)-cinnamic acid , 3,4-diphenylhexanedioic acid (4), and 3-phenylpropionic acid (5).In contrast, in the reactions of α-methyl- and phenyl-β-bromostyrenes (1b and c) the corresponding nitriles (3b and c) were formed, together with the carboxylic acids (2b and c).
- Miura, Masahiro,Shimoura, Nobuhiro,Nomura, Masakatsu
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p. 1993 - 1996
(2007/10/02)
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- Gas-Liquid Phase-transfer Catalysis: Wittig-Horner Reaction in Heterogeneous Conditions
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The Wittig-Horner synthesis of alkenes has been carried out under gas-liquid phase-transfer catalysis (g.l.-p.t.c) conditions.With this technique the carbonyl compound and the phosphonate flow, under pressure, through solid potassium carbonate contained in a thermostatted column where the conditions(temperature and pressure) are such as to ensure that the reactants are gaseous.The alkene so produced was cooled and collected at the column outlet.Reaction yields were higher when the solid potassium carbonate was coated with poly(ethylene glycol)-Carbowax 6000.The function of the poly(ethylene glycol) is discussed.Aromatic aldehydes reacts successfully with triethyl phosphonoacetate and diethyl (cyanomethyl)phosphonate; ketones react only with diethyl (cyanomethyl)phosphonate.Reaction conversions (based on the purity of the recovered alkene) are always high, while yields (measured on the basis of the actual amount of pure alkene recovered, with respect to the reacting carbonyl compound) are lower.
- Angeletti, Enrico,Tundo, Pietro,Venturello, Paolo
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p. 713 - 714
(2007/10/02)
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- REACTIONS DE WITTIG, WITTIG-HORNER ET KNOEVENAGEL PAR ACTIVATION ANIONIQUE AVEC L'ALUMINE OU LE FLUORURE DE POTASSIUM DEPOSE SUR L'ALUMINE, SANS SOLVANT.
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Wittig, Wittig-Horner and Knoevenagel reactions are achieved in the presence of alumina or potassium fluoride supported on alumina, without organic solvent.The presence of a small amount of water increases the rate of the Wittig and Wittig-Horner reactions.The reaction of the diethyl cyanomethylphosphonate with an aldehyde in the presence of dry alumina is oriented towards the Knoevenagel reaction.
- Texier-Boullet, F.,Villemin, D.,Ricard, M.,Moison, H.,Foucaud, A.
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p. 1259 - 1266
(2007/10/02)
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- Polymer-supported Phosphonates. Olefins from Aldehydes, Ketones, and Dioxolans by means of Polymer-supported Phosphonates
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Phosphonates substituted with electron-withrdrawing groups (CN and CO2Me) have been supported, by means of a neutralization reaction, on the macroreticular anion-exchange resin Amberlyst A-26.Treatment of carbonyl compounds with the polymer-bound phosphonate in various solvents gave olefins in high yields, at room temperature.Either batch or column techniques are employed, the latter offering the opportunity of a continuous procedure.The simultaneous use of the phosphonate resin and of an acidic one (Amberlyst 15 H) allowed the direct sequential hydrolysis and olefination of dioxolans.
- Cainelli, Gianfranco,Contento, Michele,Manescalchi, Francesco,Regnoli, Rodolfo
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p. 2516 - 2519
(2007/10/02)
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