- Catalytic Intermolecular C(sp3)-H Amination: Selective Functionalization of Tertiary C-H Bonds vs Activated Benzylic C-H Bonds
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A catalytic intermolecular amination of nonactivated tertiary C(sp3)-H bonds (BDE of 96 kcal·mol-1) is reported for substrates displaying an activated benzylic site (BDE of 85 kcal·mol-1). The tertiary C(sp3)-H bond is selectively functionalized to afford α,α,α-Trisubstituted amides in high yields. This unusual site-selectivity results from the synergistic combination of Rh2(S-Tfpttl)4, a rhodium(II) complex with a well-defined catalytic pocket, with tert-butylphenol sulfamate (TBPhsNH2), which leads to a discriminating rhodium-bound nitrene species under mild oxidative conditions. This catalytic system is very robust, and the reaction was performed on a 50 mmol scale with only 0.01 mol % of catalyst. The TBPhs group can be removed under mild conditions to afford the corresponding NH-free amines.
- Brunard, Erwan,Boquet, Vincent,Van Elslande, Elsa,Saget, Tanguy,Dauban, Philippe
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supporting information
p. 6407 - 6412
(2021/05/29)
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- Site-Specific Alkene Hydromethylation via Protonolysis of Titanacyclobutanes
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Methyl groups are ubiquitous in biologically active molecules. Thus, new tactics to introduce this alkyl fragment into polyfunctional structures are of significant interest. With this goal in mind, a direct method for the Markovnikov hydromethylation of alkenes is reported. This method exploits the degenerate metathesis reaction between the titanium methylidene unveiled from Cp2Ti(μ-Cl)(μ-CH2)AlMe2 (Tebbe's reagent) and unactivated alkenes. Protonolysis of the resulting titanacyclobutanes in situ effects hydromethylation in a chemo-, regio-, and site-selective manner. The broad utility of this method is demonstrated across a series of mono- and di-substituted alkenes containing pendant alcohols, ethers, amides, carbamates, and basic amines.
- Bartfield, Noah M.,Frederich, James H.,Law, James A.
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supporting information
p. 14360 - 14364
(2021/05/27)
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- Zn-Mediated Hydrodeoxygenation of Tertiary Alkyl Oxalates
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Herein we describe a general, mild, and scalable method for hydrodeoxygenation of readily accessible tertiary alkyl oxalates by Zn/silane under Ni-catalyzed conditions. The reduction method is suitable for an array of structural motifs derived from tertiary alcohols that bear diverse functional groups, including the synthesis of a key intermediate en route to estrone.
- Ye, Yang,Ma, Guobin,Yao, Ken,Gong, Hegui
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supporting information
p. 1625 - 1628
(2021/01/18)
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- Use of the 2-Pyridinesulfonyloxy Leaving Group for the Fast Copper-Catalyzed Coupling Reaction at Secondary Alkyl Carbons with Grignard Reagents
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Investigation of the copper-catalyzed coupling reaction of 2-pyridinesulfonates with Grignard reagents revealed that reactions with catalytic Cu(OTf)2 were completed in 40 min. The results differed from those of the previous CuI-catalyzed reactions of tosylates in the presence of additives (LiOMe and TMEDA) for 12-24 h. It was shown that the preferred coordination of the leaving group to the reagents accelerated the reaction. Successful reagents were MeMgCl and other RMgX. Complete inversion was established.
- Shinohara, Riku,Morita, Masao,Ogawa, Narihito,Kobayashi, Yuichi
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supporting information
p. 3247 - 3251
(2019/05/10)
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- B(C6F5)3-Catalyzed Hydrodesulfurization Using Hydrosilanes - Metal-Free Reduction of Sulfides
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B(C6F5)3-catalyzed hydrodesulfurization of carbon-sulfur bonds was achieved using triethylsilane as the reducing agent. The corresponding products were obtained in good yields under mild reaction conditions. This protocol could be applied to the reduction of sulfides, including benzyl and alkyl sulfides and dithianes, with high chemoselectivities. (Chemical Equation Presented).
- Saito, Kodai,Kondo, Kazumi,Akiyama, Takahiko
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supporting information
p. 3366 - 3369
(2015/07/15)
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- Iron-catalysed alkene hydrogenation and reductive cross-coupling using a bench-stable iron(II) pre-catalyst
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Operationally simple, iron-catalysed hydrogenation and reductive cross-coupling protocols have been developed using a bench-stable iron(ii) pre-catalyst. The hydrogenation of 18 alkenes (50-99%) and reductive cross-coupling of vinyl halides with aryl- and alkyl Grignard reagents (8 examples, 18-99%) is reported using 3 mol% pre-catalyst and hydrogen as stoichiometric reductant (1-50 bar).
- Frank, Dominik J.,Guiet, Lea,Kaeslin, Alexander,Murphy, Elliot,Thomas, Stephen P.
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p. 25698 - 25701
(2013/12/04)
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- Copper-catalyzed coupling reaction of unactivated secondary alkyl iodides with alkyl Grignard reagents in the presence of 1,3-butadiene as an effective additive
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Cu-catalyzed cross-coupling of unactivated secondary alkyl iodides with alkyl Grignard reagents in the presence of 1,3-butadiene as a ligand precursor was developed. The use of 1,3-butadiene resulted in improved yields of alkyl-alkyl products with improved selectivities.
- Shen, Ruwei,Iwasaki, Takanori,Terao, Jun,Kambe, Nobuaki
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supporting information; experimental part
p. 9313 - 9315
(2012/09/21)
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- Reduction of benzylic alcohols and α-hydroxycarbonyl compounds by hydriodic acid in a biphasic reaction medium
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The synthetic protocol for the reduction of alcohols to hydrocarbons by using hydriodic acid, first described by Kiliani more than 140 years ago, was improved to be more applicable to organic synthesis. Instead of a strongly acidic, aqueous solution, a biphasic toluene-water reaction medium was used, which allowed the conversion of primary, secondary and tertiary benzylic alcohols, in good yields and short reaction times, into the corresponding hydrocarbons. Red phosphorous was used as the stoichiometric reducing agent. Keto, ester, amide or ether groups are tolerated, and catalytic amounts of hydriodic acid (0.2 equiv) in the presence of 0.6 equiv phosphorous are sufficient to achieve conversion.
- Dobmeier, Michael,Herrmann, Josef M.,Lenoir, Dieter,Koenig, Burkhard
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supporting information; experimental part
p. 330 - 336
(2012/05/20)
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- Iron-catalysed, hydride-mediated reductive cross-coupling of vinyl halides and Grignard reagents
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An iron-catalysed, hydride-mediated reductive cross-coupling reaction has been developed for the preparation of alkanes. Using a bench-stable iron(ii) pre-catalyst, reductive cross-coupling of vinyl iodides, bromides and chlorides with aryl- and alkyl Grignard reagents successfully gave the products of formal sp3-sp3 cross-coupling reactions.
- Le Bailly, Bryden A. F.,Greenhalgh, Mark D.,Thomas, Stephen P.
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supporting information; experimental part
p. 1580 - 1582
(2012/03/26)
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- Indium-catalyzed coupling reaction between silyl enolates and alkyl chlorides or alkyl ethers
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The coupling reactions of alkyl chlorides with silyl enolates catalyzed by InBr3, and the coupling reactions of alkyl ethers with silyl enolates catalyzed by the combined Lewis acid of InBr3/Me3SiBr are described. In both reaction systems, various types of silyl enolates were used to give corresponding α-alkylated esters, ketones, carboxylic acids, amides, thioesters, and aldehydes.
- Nishimoto, Yoshihiro,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
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scheme or table
p. 5462 - 5471
(2009/12/01)
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- Boron trifluoride-catalyzed reaction of alkyl fluoride with silyl enolate, allylsilane, and hydrosilane
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Alkylation of silyl enolates with tert-alkyl or allylic fluorides proceeds smoothly in the presence of a catalytic amount of boron trifluoride to afford the corresponding carbonyl compounds. Allylation and reduction of alkyl fluorides with allylsilane and hydrosilane, respectively, occur under BF 3 catalysis.
- Hirano, Koji,Fujita, Kazuya,Yorimitsu, Hideki,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 2555 - 2557
(2007/10/03)
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- Successive carbon-carbon bond formation by sequential generation of radical and anionic species with manganese and catalytic amounts of PbCl2 and Me3SiCl
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Three-component coupling reactions of iodoalkanes, α,β-unsaturated nitriles (or esters), and carbonyl compounds are achieved in good to excellent yields with a moderate reducing system derived from manganese metal and a catalytic amount of PbCl2 and Me3SiCl. Although the role of PbCl2 is unclear, addition of a catalytic amount of the salt is essential for reducing the iodoalkane. The reaction proceeds with primary, secondary, and tertiary iodoalkanes. Both acrylonitrile and acrylic esters can be employed as activated olefins, while the reaction with an alkyl vinyl ketone gives a complex mixture. Ketones and aldehydes can be used as the third component and the diastereoselectivity of the anionic addition is approximately 1: 1-2: 1 ratio. By using the heterogenerative process, i.e., successive 1,4-addition by radical and anionic internal addition, cyclopropanation of electron- deficient olefins is achieved with chloroiodomethane, manganese, PbCl2, Me3SiCl, and DMAP.
- Takai, Kazuhiko,Ueda, Takashi,Ikeda, Norihiko,Ishiyama, Takaya,Matsushita, Hiroshi
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p. 347 - 353
(2007/10/03)
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- Formation of rearranged Grignard reagents by carbenoid-C-H insertion
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Grignard chemistry? - That is all known for more than 100 years! Thus, it is truely unexpected when a new Grignard reaction comes to light: a carbenoid C-H insertion into the α-C-H blond of a Grignard reagents.
- Hoffmann, Reinhard W.,Knopff, Oliver,Kusche, Andreas
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p. 1462 - 1464
(2007/10/03)
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- Use of Catalytic Systems Based on Aluminum Chloride in Alkylation of Benzene
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Catalytic action of supported catalysts AlCl3-MeX/SiO2, where MeX is a salt of a metal with variable valence, in alkylation of benzene with isoamyl bromide is studied for various temperatures and contact times. Binary catalytic systems are more active (with respect to the yield of amylbenzenes) than straight SiO2-supported catalysts. To a certain extent, the catalytic activity of binary systems is due to the presence of modifiers: water of crystallization and alkyl halides. The support influences the activity and selectivity of the catalysts owing to interaction between the components. Supported catalysts AlCl3-MeX/SiO2 surpass AlCl3 in selectivity and the yield of target products and suppress side processes that accompany alkylation. A mechanism is proposed for alkylation of benzene with isoamyl bromide on the catalysts prepared.
- Polubentseva,Duganova,Mikhailenko
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p. 607 - 613
(2007/10/03)
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- Geminal dialkylation, alkylative reduction and olefination of aliphatic aldehydes. Reaction of gem-bistriflates with higher order dialkylcyanocuprates
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gem-Dialkylation or alkylative reduction of α-unbranched aliphatic aldehydes 1 is advantageously achieved by reaction of the corresponding gem-bistriflates 2 with di-n-alkylcyanocuprates or di-sec- and di-tert-alkylcyanocuprates respectively. The reaction of α-branched gem-bistriflates 2 with dialkylcyanocuprates in the presence of boron trifluoride affords the olefins 6 in good yield.
- Garcia Martinez,Osio Barcina,Ruiz Diez,Subramanian
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p. 13231 - 13238
(2007/10/02)
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- Geminal Dialkylation and Alkylative Reduction of Alyphatic Aldehydes.
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gem-Dialkylation or alkylative reduction of α-unbranched aliphatic aldehydes is easily carried out by replacing the carbonyl oxygen with the gem-dihalide functionality followed by substitution of each halogen (bromine or iodine) by two n-alkyl groups or one sec- or tert-alkyl group and one hydrogen atom using higher-order dialkyl-lithium cyanocuprates.
- Martinez, A. Garcia,Fernandez, A. Herrera,Alvarez, R. Martinez,Barcina, J. Osio,Gomez, C. Garcia,Subramanian, L. R.
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p. 1063 - 1064
(2007/10/02)
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- CATYLYTIC SYNTHESIS AND REACTIONS OF MAGNESIOCYCLOALKANES. 2. SYNTHESIS OF SUBSTITUTED MAGNESIOCYCLOPENTANES IN THE PRESENCE OF ZYRCONIUM COMPLEXES
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Catalytic cyclometallation of styrene, m-methylstyrene, p-tert-butylstyrene, and 1-hexene with di n-alkylmagnesium compounds (n-R2Mg, where R=C3H7, C4H9, C6H13) in the presence of Cp2Zr2Cl2 has been given high yields of 2,4-disubstituted magnesiocyclopentanes.The probable mode of formation of magnesiocyclopentanes, involving zirconocyclopentanes formed from Cp2ZrCl2, n-R2Mg, and the appropiate olefins as reactive intermediates in the cyclometallation, is discussed. Keywords: catalytic synthesis, substituted styrenes, alkenes, magnesium alkyls.
- Dzhemilev, U. M.,Sultanov, R. M.,Gaimaldinov, R. G.,Muslukhov, R. R.,Lomakina, S. I.,Tolstikov, G. A.
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p. 770 - 788
(2007/10/02)
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- The action of sodium hydrogen telluride on olefins
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The action of sodium hydrogen telluride, NaTeH, on non electrophilic carbon-arbon double bonds has been investigated.The reaction is found to be very sensitive to the substituents on the ethylenic linkage. Whereas phenyl conjugated olefins are reduced to alkylbenzenes,the reagent adds to isolated mono and disubstituted double bonds leading to organotellurium derivatives and with gem-disubstituted ones it leads to a mixture of reduction and addition products. These results are interpreted in terms of a radical pair mechanism involving hydrogen atom transfer from hydrogen telluride,HTe- to the double bond.
- Barton, Derek H. R.,Bohe, Luis,Lusinchi, Xavier
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p. 5273 - 5284
(2007/10/02)
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- The addition of sodium hydrogen telluride to unactivated carbon-carbon double bonds
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The reaction of unhindered olefins with sodium hydrogen telluride in refluxing ethanol produces dialkyltellurides by an addition process which shows prominent Markownikov selectivity.
- Barton,Bohe,Lusinchi
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- Oxidation-Reduction Hydration of Olefins with Molecular Oxygen and 2-Propanol Catalyzed by Bis(acetylacetonato)cobalt(II)
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In the presence of a catalytic amount of bis(acetylacetonato)cobalt(II), various olefins are hydrated with oxygen and secondary alcohol to afford the corresponding alcohols together with alkanes and ketones via Oxidation-Reduction process.Effect of additives in the present hydration reaction shows that 2,6-lutidine and 2-picoline inhibit the production of alkanes in a large extent to result in the better yielding of alcohols.
- Mukaiyama, Teruaki,Isayama, Shigeru,Inoki, Satoshi,Kato, Koji,Yamada, Tohru,Takai, Toshihiro
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p. 449 - 452
(2007/10/02)
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- Electrosynthesis of Organic Compounds, VII. Electrochemical Oxidation of Selected Arylalkyl Halides
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Anodic oxidation of selected arylalkyl halides was carried out in methanol containing 0.05 mol.l-1 Ba(ClO4)2, as electrolyte on a platinum anode at + 1.7 V vs SCE.The compounds electrochemically oxidized were benzyl bromide (1), 2-phenylethyl bromide (2), 3-phenylpropyl bromide (3), 4-phenylbutyl chloride (4), 1-methyl-3-phenylpropyl chloride (5) and 1,1-dimethyl-3-phenylpropyl chloride (6).The principal products isolated were the corresponding alkylbenzenes, alkenylbenzenes, dimers, ethers and cyclic products.Mechanisms were suggested.Also, kinetic studies were carried out on carbon-halogen bond cleavage of the compounds investigated (1-6).Current-potential curves were drawn, and discharge oxidation potentials were determined from these.
- Ismail, M. T.,Abdel-Wahab, A. A.,El-Khawaga, A. M.,Mohamed, O. S.,Khalaf, A. A.
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- Electrosynthesis of Organic Compounds. V. Electrochemical Reduction of Selected Arylalkyl Halides
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Electrochemical reductions of some selected arylalkyl halides were carried out in methanol containing 0.1 mol*l-1 Ba(ClO4)2 on different cathodes (Hg, Zn).The compounds investigated were benzyl bromide (1); phenylethyl bromide (2); 3-phenylpropyl bromide (3); 4-phenylbutyl chloride (4); 1-methyl-3-phenylpropyl chloride (5); 1,1-dimethyl-3-phenylpropyl chloride (6) and 1,1-dimethyl-4-phenylbutyl chloride (7).The isolated products were found to include hydrogen abstraction, dehydrogenation, dimerization as well as cyclization products.Suitable mechanism involving the formation of intermediate carbanions and of free radicals was suggested to explain the results.Also, polarization curves for the compounds investigated were measured and the reduction half-wave potentials were determined.
- Ismail, M. T.,Abdel-Wahab, A. A.,Mohamed, O. S.,Khalaf, A. A.
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p. 1174 - 1176
(2007/10/02)
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- Reactions of ?-Allylic Palladium Intermediates with Amines
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Several dimeric ?-allylic palladium chloride complexes have been prepared by addition of aryl-, hydrido-, and (carbomethoxy)palladium chlorides, prepared in situ, to various conjugated dienes.Stoichiometric reactions of several of these complexes with secondary amines were carried out and the influence of added ligands and changes in the anions in the complexes on the reactions were noted.The stoichiometric reactions were then compared to similar catalytic reactions.The evidence suggests that the products formed in the palladium-catalyzed reactions of aryl iodides and bromides with conjugated dienes and secondary amines to form arylated dienes and allylic amines involve ?-allylic palladium complexes as intermediates.
- Stakem, Francis, G.,Heck, Richard F.
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p. 3584 - 3593
(2007/10/02)
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- Palladium-Catalyzed Triethylammonium Formate Reductions. 4. Reduction of Acetylenes to Cis Monoenes and Hydrogenolysis of Tertiary Allylic Amines
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Eight phenyl-conjugated and double bond conjugated acetylenes were reduced with triethylammonium formate and a palladium on carbon catalyst.Cis olefins were obtained in good yields in five examples. 4-Nitrodiphenylacetylene gave only 4-aminodibenzyl and (Z)-methyl non-2-en-4-ynoate gave mainly the E,Z dienoate. 1-Phenyl-3-methylbut-3-en-1-yne gave the cis diene initially, but it isomerized partially under the reaction conditions.Five tertiary allylic amines were shown to undergo hydrogenolysis with the same reducing agent and catalyst to give mixtures of two isomeric olefins in moderate to good yields.
- Weir, John R.,Patel, Babu A.,Heck, Richard F.
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p. 4926 - 4931
(2007/10/02)
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