- Direct Deamination of Primary Amines via Isodiazene Intermediates
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We report here a reaction that selectively deaminates primary amines and anilines under mild conditions and with remarkable functional group tolerance including a range of pharmaceutical compounds, amino acids, amino sugars, and natural products. An anomeric amide reagent is uniquely capable of facilitating the reaction through the intermediacy of an unprecedented monosubstituted isodiazene intermediate. In addition to dramatically simplifying deamination compared to existing protocols, our approach enables strategic applications of iminium and amine-directed chemistries as traceless methods. Mechanistic and computational studies support the intermedicacy of a primary isodiazene which exhibits an unexpected divergence from previously studied secondary isodiazenes, leading to cage-escaping, free radical species that engage in a chain, hydrogen-atom transfer process involving aliphatic and diazenyl radical intermediates.
- Berger, Kathleen J.,Driscoll, Julia L.,Yuan, Mingbin,Dherange, Balu D.,Gutierrez, Osvaldo,Levin, Mark D.
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supporting information
p. 17366 - 17373
(2021/11/04)
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- Intermolecular Allene Functionalization by Silver-Nitrene Catalysis
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Under silver catalysis conditions, using [Tp*,BrAg]2 as the catalyst precursor, allenes react with PhI═NTs in the first example of efficient metal-mediated intermolecular nitrene transfer to such substrates. The nature of the substituent at the allene seems crucial for the reaction outcome since arylallenes are converted into azetidine derivatives, whereas methylene aziridines are the products resulting from alkylallenes. Mechanistic studies allow proposing that azetidines are formed through unstable cyclopropylimine intermediates, which further incorporate a second nitrene group, both processes being silver-mediated. Methylene aziridines from alkylallenes derive from catalytic nitrene addition to the allene double bonds. Both routes have resulted to be productive for further synthetic transformations affording aminocyclopropanes.
- Rodríguez, Manuel R.,Besora, María,Molina, Francisco,Maseras, Feliu,Díaz-Requejo, M. Mar,Pérez, Pedro J.
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p. 13062 - 13071
(2020/09/01)
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- Stereoselective annulation between an allene, an alkene, and two nitrosoarenes to access bis(isoxazoliodine) derivatives
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This work reports metal-free annulations between one allene, two nitrosoarenes and one electron-deficient alkene to afford bis(isoxazolidine) derivatives stereoselectively. This process involves an initial formation of isoxazolidin-4-imine oxides, followe
- Sharma, Pankaj,Jadhav, Prakash D.,Skaria, Manisha,Liu, Rai-Shung
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supporting information
p. 9389 - 9397
(2017/11/22)
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- Enantioselective, Stereodivergent Hydroazidation and Hydroamination of Allenes Catalyzed by Acyclic Diaminocarbene (ADC) Gold(I) Complexes
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The gold-catalyzed enantioselective hydroazidation and hydroamination reactions of allenes are presented herein. ADC gold(I) catalysts derived from BINAM were critical for achieving high levels of enantioselectivity in both transformations. The sense of enantioinduction is reversed for the two different nucleophiles, allowing access to both enantiomers of the corresponding allylic amines using the same catalyst enantiomer. Chiral allylic azides and amines are obtained by enantioselective hydroazidation and hydroamination of allenes catalyzed by acyclic diaminocarbene gold(I) catalysts derived from BINAM. The sense of enantioinduction is reversed for the two different nucleophiles, allowing easy access to both enantiomers with a single catalyst enantiomer.
- Khrakovsky, Dimitri A.,Tao, Chuanzhou,Johnson, Miles W.,Thornbury, Richard T.,Shevick, Sophia L.,Toste, F. Dean
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supporting information
p. 6079 - 6083
(2016/05/19)
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- Organomagnesium-catalyzed isomerization of terminal alkynes to allenes and internal alkynes
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Organomagnesium complexes 2 were synthesized from N,N-dialkylamineimine ligands 1 and dibenzylmagnesium by benzylation of the imine moiety. 3-Aryl-1-propynes reacted with 2 to form the corresponding tetraalkynyl complexes, which acted as catalysts for the transformation of these terminal alkynes into allenes and further to internal alkynes under mild conditions. To the best of our knowledge, this example is the first of an organomagnesium-catalyzed isomerization of alkynes. Notably, the reactions proceeded through temporally separated autotandem catalysis, thus allowing the isolation of the allene or internal alkyne species in good yields. Mechanistic experiments suggested that the catalytically active tetraalkynyl complexes consist of a tautomeric mixture of alkynyl-, allenyl-, and propargylmagnesium species.
- Rochat, Rapha?l,Yamamoto, Koji,Lopez, Michael J.,Nagae, Haruki,Tsurugi, Hayato,Mashima, Kazushi
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p. 8112 - 8120
(2015/05/27)
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- Nickel-catalyzed substitution reactions of propargyl halides with organotitanium reagents
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A simple and mild catalytic coupling reaction of propargyl halides with organotitanium reagents is reported. The reaction of propargyl bromide with organo-titanium reagents mediated by NiCl2(2 mol%) and PCy3(4 mol%) in CH2
- Li, Qing-Han,Liao, Jung-Wei,Huang, Yi-Ling,Chiang, Ruei-Tang,Gau, Han-Mou
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p. 7634 - 7642
(2014/12/11)
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- Gold-catalyzed hydrofunctionalization of allenes with nitrogen and oxygen nucleophiles and its mechanistic insight
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A wide range of nucleophiles, such as amines and alcohols, reacted intermolecularly with various allenes in the presence of gold catalysts to give the corresponding hydrofunctionalization products in high yields. The intermolecular hydroamination of chira
- Nishina, Naoko,Yamamoto, Yoshinori
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body text
p. 1799 - 1808
(2009/06/28)
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- 1,3-Li/H shift of 1-Aryl-1,2-alkadienyl reagents: An experimental and theoretical study
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A mechanism involving the exchange of equilibrated protons initiated by a catalytic amount of a proton donor, the most effective of which appears to be di-isopropylamine was proposed. The thermodynamic potential of the rearrangement was first examined com
- Alouane, Nacira,Bentayeb, Kamel,Vrancken, Emmanuel,Gerard, Helene,Mangeney, Pierre
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body text
p. 45 - 48
(2009/06/18)
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- Regio- And stereoselective synthesis of alkyl allylic ethers via gold(l)-catalyzed intermodular hydroalkoxylation of allenes with alcohols
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Reaction of 1-phenyl-1,2-butadiene with 2-phenyl-1-ethanol catalyzed by a 1:1 mixture of a gold(l) W-heterocyclic carbene complex and AgOTf at room temperature for 1 h led to isolation of (E)-(3-phenethoxy-1-butenyl)benzene in 96% yield as a single regio-
- Zhang, Zhibin,Widenhoefer, Ross A.
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supporting information; experimental part
p. 2079 - 2081
(2009/04/10)
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- Gold-catalyzed intermolecular hydroalkoxylation of allenes; difference in mechanism between hydroalkoxylation and hydroamination
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A wide range of alcohols 2 react with various allenes 1 in the presence of ClAuPPh3/AgOTf catalyst at ambient temperature without solvent to produce allylic ethers 3. Contrary to the hydroamination, which proceeds through high chiral-face selec
- Nishina, Naoko,Yamamoto, Yoshinori
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p. 4908 - 4911
(2008/09/21)
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- Chromium(0)-Promoted [6π + 2π] cycloadditions of allenes with cycloheptatriene
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(Chemical Equation Presented) Photoinitiated [6π + 2π] cycloadditions of allenes with (η6-cycloheptatriene)tricarbonylchromium(0) (1) are described. An example of asymmetric induction obtained by reaction of 1 with a chiral 1,3-disubstituted al
- Rigby, James H.,Laurent, Stephane B.,Kamal, Zeeshan,Heeg, Mary Jane
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supporting information; experimental part
p. 5609 - 5612
(2009/06/18)
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- Synthesis of allenes by palladium-catalyzed SN2′ reaction of indium organometallics with propargylic esters
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Allenes have been efficiently prepared by the reaction of propargylic esters (benzoates, acetates, carbonates) with triorganoindium compounds (R 3In) under palladium catalysis, via an SN2′ rearrangement. The reaction proceeds smoothl
- Riveiros, Ricardo,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 3595 - 3598
(2008/09/19)
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- Palladium-catalyzed cross-coupling reaction of triorganoindium reagents with propargylic esters
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Triorganoindium reagents (R3In) react with propargylic esters under palladium catalysis via an SN2′ rearrangement to afford allenes in good yields and with high regioselectivity. The reaction proceeds smoothly at room temperature wit
- Riveiros, Ricardo,Rodriguez, David,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 1403 - 1406
(2007/10/03)
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- Stereoselective synthesis of chiral 3-aryl-1-alkynes from bromoallenes and heterocuprates
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The synthesis of chiral 3-aryl-1-alkynes 3 via cross-coupling of 3-alkyl- and 3,3-dialkyl-1-bromo-1,2-dienes 1 and arylbromocuprates (RCuBr)MgBr-LiBr 2 was examined. With phenylcopper reagents and its para-substituted derivatives, as well as with 2-naphth
- Caporusso, Anna Maria,Zampieri, Alessia,Aronica, Laura Antonella,Banti, Donatella
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p. 1902 - 1910
(2007/10/03)
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- Highly chemoselective coupling of allenylstannanes with organic iodides promoted by Pd(PPh3)4/LiCl: An efficient method for the synthesis of substituted allenes
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An efficient method for the preparation of various monosubstituted arylallenes, disubstituted allenes and alkenylallenes via palladium-catalyzed coupling of allenylstannanes with aryl iodides or alkenyl iodides is described. The coupling reaction was carr
- Huang, Chih-Wei,Shanmugasundaram, Muthian,Chang, Hao-Ming,Cheng, Chien-Hong
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p. 3635 - 3641
(2007/10/03)
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- Synthesis of allenes from allylic alcohol derivatives bearing a bromine atom using a palladium(0)/diethylzinc system
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A general and efficient synthesis of allenes using a palladium(0)/diethylzinc system is described. Treatment of mesylates or trichloroacetates of (E)- or (Z)-2-bromoalk-2-en-1-ols with diethylzinc in the presence of a catalytic amount of palladium(0) affords allenes bearing an aminoalkyl, alkyl, or aryl substituent(s) in good to high yields. No transfer of chirality from the stereogenic center carrying the mesyloxy group to the allene was observed.
- Ohno, Hiroaki,Miyamura, Kumiko,Tanaka, Tetsuaki,Oishi, Shinya,Toda, Ayako,Takemoto, Yoshiji,Fujii, Nobutaka,Ibuka, Toshiro
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p. 1359 - 1367
(2007/10/03)
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- Synthesis of allenes by double Horner-Wadsworth-Emmons reaction
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LDA treatment of aldehydes or ketone with alkenylphosphonates 2, prepared by Horner-Wadsworth-Emmons (HWE) reaction of methylenebisphosphonate 1 with aldehydes, afforded Baylis-Hillman reaction-type products 5 in high yields. HWE olefination of 5 with KH or KH-18-crown-6 as a base provided allenes in good yields. One-flask procedure was successfully developed starting from 1 to afford an allene in a reasonably good yield.
- Inoue, Hideki,Tsubouchi, Hiroshi,Nagaoka, Yasuo,Tomioka, Kiyoshi
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- Allenes through Horner-Wadsworth-Emmons olefination of alkenylphosphonates
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Mono- and di-substituted allenes 5 were synthesized by successive Horner-Wadsworth-Emmons olefination starting from methylene-bisphosphonate 1 and two carbonyl compounds. The key to success is KH or KH-18-crown-6 as a base for the second HWE olefination o
- Nagaoka, Yasuo,Inoue, Hideki,Tomioka, Kiyoshi
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p. 1843 - 1846
(2007/10/03)
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- Vinyl carbocations: Solution studies of alkenyl(aryl)iodonium triflate fragmentations
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Generation of vinyl cations is facile by fragmentation of alkenyl(aryl)iodonium trifluoromethanesulfonates. Kinetics and electronic effects were probed by 1H NMR spectroscopy in CDCl3. Products of fragmentation include six enol triflate isomers in addition to iodoarenes. The enol triflates arise from direct reaction of a triflate anion with the starting iodonium salts as well as triflate reaction with rearranged secondary cations derived from those salts. G2 calculations of the theoretical isodesmic hydride-transfer reaction between secondary vinyl cation 7 and primary vinyl cation 6 reveal that cation 6 is 17.8 kcal/mol higher in energy. Activation parameters for fragmentation of (Z)-2-ethyl-1-hexenyl(3,5-bis-trifluoromethylphenyl)iodonium triflate, 17e, were calculated using the Arrhenius equation: Ea = 26.8 kcal/mol, ΔH? = 26.2 kcal/mol, and ΔS? = 11.9 cal/mol·K. Added triflate increases the rate of fragmentation slightly, and it is likely that for most β,β-dialkyl-substituted vinylic iodonium triflates enol triflate fragmentation products are derived from three competing mechanisms: (a) vinylic SN2 substitution; (b) ligand coupling (LC); and (c) concerted aryliodonio departure and 1,2-alkyl shift leading to secondary rather than primary vinyl cations.
- McNeil,Hinkle,Rouse,Thomas,Thomas
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p. 5556 - 5565
(2007/10/03)
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- Palladium-catalyzed coupling of stannyl allenes with aryl iodides
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Substituted allenes are prepared by coupling stannyl allenes with aryl iodides under palladium(0) catalysis. A concise and versatile sequence starting from propargyl alcohols provides a route for the preparation of substituted allenes under extremely mild conditions.
- Aidhen,Braslau
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p. 789 - 797
(2007/10/02)
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- Electrolytically Induced Allene-Alkyne Isomerization
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Preparative-scale electrolyses at mercury cathodes in dimethylformamide containing tetra-n-butylammonium perchlorate have revealed that 1-phenyl-1,2-hexadiene exhibits no evidence of isomerization to form 1-phenyl-1-hexyne via an electrolytically induced, base-catalyzed rearrangement; similarly, 1-phenyl-1,2-butadiene exhibits only a slight tendency (1-2percent) to form 1-phenyl-1-butyne.In contrast, voltammetric and electrolytic experiments demonstrate that isomerization of 1-phenyl-1-butyne, 1-phenyl-1-pentyne, and 1-phenyl-1-hexyne to the corresponding allenes occurs muchmore readily.Observations from several investigations show that the extent of allene-to-alkyne rearrangement increases from 1-phenyl-1,2-hexadiene to 1-phenyl-1,2-butadiene to phenylpropadiene, whereas the reverse alkyne-to-allene isomerization decreases in significance from 1-phenyl-1-hexyne to 1-phenyl-1-pentyne to 1-phenyl-1-butyne to 1-phenyl-1-propyne.Steric and electronic factors, which affect protonation of the conjugate bases of the various starting materials at acrbons 1 and 3, can be invoked to explain these trends.
- Stemple, Joseph Z.,Peters, Dennis G.
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p. 5318 - 5323
(2007/10/02)
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- ALLENE SYNTHESIS FROM 2-ALKYN-1-OLS
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Activation of 2-alkyn-1-ols as their methanesulfonate esters and displacement with hydrazine furnishes the corresponding alkynyl hydrazine derivatives which undergo smooth oxidative rearrangement with diethyl azodicarboxylate (DEAD) or 4-methyl-1,2,4-tria
- Myers, Andrew G.,Finney, Nathaniel S.,Kuo, Elaine Y.
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p. 5747 - 5750
(2007/10/02)
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- Highly Stereoselective Synthesis of Chiral Alkylallenes by Organocopper(I)-Induced Anti 1,3-Substitution of Chiral Propynyl Esters
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The synthesis of chiral 1,3-dialkylallenes R1CH=C=CHR2 of high enantiomeric purity, by applying homogeneous reaction between organocopper(I) reagents of type 2CuX>MgX-LiX> and chiral propynyl methanesulfonates or sulfinates at low temperatures in THF, is reported.The reactions are generally fast; typically complete conversion is obtained within a few minutes at -60 deg C.Overall, high anti stereoselectivity is observed.A plausible mechanism is put forward, and comparison is made with the stereochemistry of reactions of comparable substrates with d10 complexes, e.g. of Pd(0).
- Elsevier, Cornelis J.,Vermeer, Peter
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p. 3726 - 3730
(2007/10/02)
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- AN ASYMMETRIC HYDROGEN EQUIVALENT: USE OF THE 1-NAPHTHYLPHENYLMETHYLSILYL GROUP IN THE PREPARATION OF OPTICALLY ACTIVE ALLYL ALCOHOLS AND (S) 1-PHENYL-1,2-BUTADIENE.
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The potential of using a chiral organosilane as a single antipode at silicon in the preparation and separation of diastereomers has been demonstrated.
- Torres, Evelyn,Larson, Gerald L.,McGarvey, Glenn J.
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p. 1355 - 1358
(2007/10/02)
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- REACTIONS OF 3-ALKYL- AND 3,3-DIALKYL-1-BROMOALLENES WITH ORGANOCUPRATES: EFFECTS OF THE NATURE OF THE CUPRATE REAGENT ON THE REGIO- AND STEREOSELECTIVITY
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Organocuprates induce 1,3- and direct substitution in 3-alkyl- and 3,3-dialkyl-1-bromo-1,2-dienes leading respectively to either terminal acetylenes or allenic hydrocarbons.The nature of the cuprate exerts a prominent role in determining both the regio- and the stereochemistry of these reactions.
- Caporusso, Anna Maria,Polizzi, Carmela,Lardicci, Luciano
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p. 6073 - 6076
(2007/10/02)
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- CHIRAL RECOGNITION OF ALLENIC HYDROCARBONS BY 1H NMR
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The syntheses of the allenes (+/-)-1, (+/-)-4, and (+/-)-6 as well as of the enriched samples (-)-1, (-)-4 and (-)-6 are described. 1H NMR shifts and splittings induced by a mixture of the achiral salt Ag(fod) and the optically active complex (+)-Yb(hfbc)
- Mannschreck, A.,Munninger, W.,Burgemeister, T.,Gore, J.,Cazes, B.
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p. 399 - 408
(2007/10/02)
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- MECHANISMES DE LA PROTONOLYSE DES ORGANO-CHROMIQUES ISSUS DE BROMURES PROPARGYLIQUES.
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The reaction of CrCl2 with propargylic bromides leads to an allenic organo-chromic derivative protonated without rearrangement by carboxylic acids.Alcohols like menthol transform this metallic to its propargylic isomer and then protonate it with rearrangement(SEi' type mechanism).
- Cazes, Bernard,Verniere, Catherine,Gore, Jacques
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p. 3501 - 3504
(2007/10/02)
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- Highly Selective Carbon-Carbon Bond Forming Reactions Mediated by Chromium(II) Reagents
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A low valent chromium reagent is generated from chromium(III) chloride and a half mol of lithium aluminum hydride in tetrahydrofuran.The reagent behaves similarly to anhydrous chromium(II) chloride, which is commercially available, and reduces allylic halides to produce unisolable allylchromium species which add efficiently to aldehydes or ketones with high degree of stereo- and chemoselectivity.Particularly, high threo selectivity is observed in the reaction of aldehydes and 1-bromo-2-butene and is ascribed to a chair-like six-membered transition state.Simple reduction od allylic and benzylic halides produces biallyls and bibenzyls, while gem-dibromocyclopropanes afford the corresponding allenes in excellent yields.
- Hiyama, Tamejiro,Okude, Yoshitaka,Kimura, Keizo,Nozaki, Hitosi
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p. 561 - 568
(2007/10/02)
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- NOUVELLE VOIE D'ACCES A DES ALLENES ET VINYLALLENES ENANTIOMERIQUEMENT ENRICHIS.
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The reduction of three racemic propargylic bromides by Hiyama's reagent (CrCl2 in THF) in the presence of protonic chiral reagents and HMPT efficiently affords optically active allenic compounds with an enantiomeric purity of 15-25 percent.
- Verniere, Catherine,Cazes, Bernard,Gore, Jacques
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p. 103 - 106
(2007/10/02)
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- PALLADIUM(0)-PROMOTED SYNTHESIS OF FUNCTIONALLY SUBSTITUTED ALLENES BY MEANS OF ORGANOZINC COMPOUNDS
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The paper describes new routes to aryl-, vinyl-, and 1-alkynylallenes and to diallenes via Pd(PPh3)4-promoted reaction of propargylic or allenic halides with appropriate organozinc halides.Propargylic acetates are also suited to prepare such allenes.
- Ruitenberg, K.,Kleijn, H.,Elsevier, C. J.,Meijer, J.,Vermeer, P.
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p. 1451 - 1452
(2007/10/02)
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