- Exploring Site Selectivity of Iridium Hydride Insertion into Allylic Alcohols: Serendipitous Discovery and Comparative Study of Organic and Organometallic Catalysts for the Vinylogous Peterson Elimination
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The vinylogous Peterson elimination of a broad range of primary, secondary, and tertiary silylated allylic alcohols by two distinct and complementary catalytic systems - a cationic iridium complex and a Br?nsted acid - is reported. These results are unexpected. Nonsilylated substrates are typically isomerized into aldehydes and silylated allylic alcohols into homoallylic alcohols with structurally related iridium complexes. Although several organic acids and bases are known to promote the vinylogous Peterson elimination, the practicality, mildness, functional group tolerance, and generality of both catalysts are simply unprecedented. Highly substituted C=C bonds, stereochemically complex scaffolds, and vicinal tertiary and quaternary (stereo)centers are also compatible with the two methods. Both systems are stereospecific and enantiospecific. After optimization, a vast number of dienes with substitution patterns that would be difficult to generate by established strategies are readily accessible. Importantly, control experiments secured that traces of acid that may be generated upon decomposition of the in situ generated iridium hydride are not responsible for the activity observed with the organometallic species. Upon inspection of the reaction scope and on the basis of preliminary investigations, a mechanism involving iridium-hydride and iridium-allyl intermediates is proposed to account for the elimination reaction. Overall, this study confirms that site selectivity for [Ir-H] insertion across the C=C bond of allylic alcohols is a key parameter for the reaction outcome.
- Li, Houhua,Fiorito, Daniele,Mazet, Clément
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p. 1554 - 1562
(2017/08/15)
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- Conjugated diene-assisted allylic C-H bond activation: Cationic Rh(I)-catalyzed syntheses of polysubstituted tetrahydropyrroles, tetrahydrofurans, and cyclopentanes from Ene-2-dienes
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C-H activation followed by addition to alkenes is challenging in the current C-H activation/functionalization field. We report herein an unprecedented diene-assisted transition-metal-catalyzed activation of allylic C-H bonds and their subsequent insertion
- Li, Qian,Yu, Zhi-Xiang
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supporting information; experimental part
p. 4542 - 4543
(2010/06/13)
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- A strategy for the synthesis of well-defined iron catalysts and application to regioselective diene hydrosilylation
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We report the development of a well-defined Fe catalyst and its application to the regio-and stereoselective 1,4-hydrosilylation of 1,3-dienes. To the best of our knowledge, this is the first example of accessing a characterized low-valent Fe catalyst by controlled reductive elimination from a readily accessible Fe precatalyst.
- Wu, Jessica Y.,Stanzl, Benjamin N.,Ritter, Tobias
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supporting information; experimental part
p. 13214 - 13216
(2010/12/19)
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- First regio- and enantioselective chromium-catalyzed homoallenylation of aldehydes
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Game, set, and match: The first regio- and enantioselective version of the title reaction is described. The chiral catalyst prepared in situ from CrCl 3 and a non-C2-symmetric bis(oxazoline) ligand 1 affords the valuable chiral ss-al
- Coeffard, Vincent,Aylward, Miriam,Guiry, Patrick J.
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supporting information; experimental part
p. 9152 - 9155
(2010/03/03)
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- Synthetic method for the preparation of 2-aminomethyl-1,3-diene derivatives through indium-mediated 1,3-butadien-2-ylation of imines
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An efficient method for the preparation of a variety of 2-aminomethyl-1,3-dienes was developed through the reaction of imines with organoindium reagent generated in situ from indium and 1,3-dibromo-2-butyne. Three-component reactions of aldehydes, amines,
- Seomoon, Dong,Jaemyung A.,Lee, Phil Ho
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supporting information; experimental part
p. 2401 - 2404
(2009/10/10)
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- Nucleophilic reactivity of 1-zirconacyclopent-3-ynes: Carbon-carbon bond formation with aldehydes
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Nucleophilic reactions of 1,1-bis(η5-cyclopentadienyl)-1-zirconacyclopent-3-yne (1) with proton and aldehydes were studied. The reaction with HCl gave a mixture of 2-butyne and 1,2-butadiene. Complex 1 reacted with benzaldehyde to give 1-phenyl-2-methyl-2,3-butadien-1-ol (3) in moderate yields in the presence of a proton source such as triethylammonium hydrochloride, while it gave 2-methylene-1-phenyl-3-buten-1-ol (4) on using triethylammonium tetraphenylborate.
- Suzuki, Noriyuki,Watanabe, Takaaki,Hirose, Takuji,Chihara, Teiji
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p. 5317 - 5321
(2008/03/12)
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- Organometallic reactions in aqueous media. Indium-mediated 1,3-butadien-2-ylation of carbonyl compounds
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(Equation Presented) Indium-mediated coupling of 1,4-dibromo-2-butyne with carbonyl compounds in aqueous media gave good yields of the 1,3-butadien-2-ylmethanols.
- Lu, Wenshuo,Ma, Jihai,Yang, Yang,Chan, Tak Hang
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p. 3469 - 3471
(2007/10/03)
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- Expanded scope in ethylene-alkyne cross-metathesis: coordinating heteroatom functionality at the propargylic position.
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The Grubbs 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium complex 1 catalyzed ethylene-alkyne cross-metathesis and was shown to tolerate free hydroxyl groups and coordinating functionality at the propargylic and homopropargylic position
- Smulik,Diver
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p. 2271 - 2274
(2007/10/03)
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- Regioselective buta-1,3-dienylation of aldehydes via transmetallation of 2-tributylstannylbuta-1,3-diene
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Transmetallation of 2-tributylstannylbuta-1,3-diene with SnCl4 followed by Lewis base promoted addition of the resulting 1-trichlorostannyl-2,3-butadiene to aldehydes in the presence of DMF allows their buta-1,3-dienylation to take place at the
- Luo, Meiming,Iwabuchi, Yoshiharu,Hatakeyama, Susumi
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p. 1109 - 1111
(2007/10/03)
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- Buta-2,3-dienylstannanes, effective reagents for regioselective buta-1,3-dienylation of aldehydes and acetals
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Two buta-2,3-dienylstannanes, 1-tri-n-butylstannylbuta-2,3-diene and 1-triphenylstannylbuta-2,3-diene, have been prepared and shown to react with aldehydes and acetals under Lewis acid catalyzed conditions producing (buta-1,3-dien-2-yl)methanol derivative
- Luo, Meiming,Iwabuchi, Yoshiharu,Hatakeyama, Susumi
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p. 267 - 268
(2007/10/03)
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- Highly efficient synthesis of alka-1,3-dien-2-yltitanium compounds from alka-2,3-dienyl carbonates. A new, practical synthesis of 1,3-dienes and 2-iodo-1,3-dienes
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Treatment of carbonates of alka-2,3-dien-1-ols 2 with (η2-propene)Ti(O-i-Pr)2 (1) resulted in oxidative addition to afford 1,3-dien-2-yltitanium compounds 3, which react readily with electrophiles such as H+, I2
- Okamoto, Sentaro,Sato, Hiroyoshi,Sato, Fumie
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p. 8865 - 8868
(2007/10/03)
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- Chiral Synthesis via Organoboranes. 44. Racemic and Diastereo- and Enantioselective Homoallenylboration Using Dialkyl 2,3-Butadien-1-ylboronate Reagents. Another Novel Application of the Tandem Homologation-Allylboration Strategy
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A highly general and efficient racemic and diastereo- and enantioselective homoallenylboration has been achieved with a novel boron reagent, dialkyl 2,3-butadien-1-ylboronate (dialkyl homoallenylboronate).The starting isopropyl 2,3-butadien-1-ylboronate is prepared from allenylmagnesium bromide and diisopropyl (halomethyl)boronate.This β,γ-unsaturated boronate reagent reacts readily with aldehydes via usual allylic rearrangement to give the alkyl(1,3-butadien-2-yl)methanols in excellent yields.Among the solvents examined, toluene favored enhanced reaction rates.The reaction is relatively sensitive to steric effects, so that sterically hindered aldehydes react significantly slower.Generaly, the reactivities are moderately lower than those of the corresponding simple allylboronates, possibly due to the reduced HOMO electron density of the internal double bond.Also, the reagent exhibits a unique anti diastereoselectivity in reaction with α-chiral aldehydes in contrast to the syn selectivity observed with a corresponding organosilicon reagent.However, this anti selectivity is similar to that observed for the allylboration reactions.We have successfully extended this reaction to the first general synthesis of optically active alkyl(1,3-butadien-2-yl)methanol using chiral tartrate boronate reagents with diisopropyl tartrate (DIPT) and bis(2,4-dimethyl-3-pentyl) tartrate (DMPT) as the chiral modifiers.These reagents react with aldehydes even at -78 deg C, albeit slowly, and exhibit remarkable enantioselectivity with al classes of aldehydes examined with the exception of aromatic and α-alkoxy aldehydes.Again, while the selectivity parallels that of the corresponding allylboronate, the reactivities are lower.Also, the double asymmetric homoallenylboronation of 2,3-O-isopropylidene-D-glyceraldehyde using the DMPT modified boronate reagent gives an excellent 98.5percent anti selectivity in the matched case and a moderately lower value, 82percent syn selectivity, in the mismatched case.
- Ramachandran, P. Veeraraghavan,Li, Guisheng,Brown, Herbert C.
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p. 100 - 104
(2007/10/03)
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- Racemic and diastereoselective synthesis of alkyl(1,3-butadien-2-yl) methanols via a novel homoallenylboration of aldehydes with diisopropyl 2,3-butadien-1-ylboronate
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Diisopropyl 2,3-butadien-1-ylboronate has been prepared by a simple method and its utility as a novel homoallenylborating reagent has been demonstrated with a series of aldehydes. Also, a high diastereoselectivity of this reagent in its reaction with an α
- Brown, Herbert C.
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p. 2441 - 2444
(2007/10/02)
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- Synthesis of pinacol esters of 2,3-alkadienylboronic acid via the copper(I) mediated coupling reaction of Knochel's (dialkoxyboryl)methylzinc reagents with propargylic tosylates
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The reaction of propargyl tosylates (1) with (dialkoxyboryl)methylcopper(I) reagents, prepared in situ from Knochel's (dialkoxyboryl)methylzinc iodide (2) and CuCN*2LiCl, produced 2,3-alkadienylboronates (3) in moderate yields. The reaction proceeded regi
- Gridnev, Ilya,Kanai, Gen,Miyaura, Norio,Suzuki, Akira
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- Thermal and Catalyzed Diels-Alder Reactions with Chiral 2-Substituted-1,3-dienes: Conformational Models for Diastereofacial Selectivity
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The thermal or BF3-catalyzed Diels-Alder reactions of chiral 2-substituted-1,3-dienes bearing a hydroxy or a protected hydroxy group at the allylic position with various dienophiles have been studied in order to determine the regio- and stereoselectice co
- Bloch, Robert,Chaptal-Gradoz, Nathalie
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p. 4162 - 4169
(2007/10/02)
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- Diastereofacial selectivity in Diels-Alder reactions of chiral 2-substituted-1,3-dienes
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Starting from chloroprene, an improved synthesis of alkyl and aryl (1,3-butadien-2-yl) methanols 1 is described. Thermal Diels-Alder reactions between these dienols or their ethers 3 and various dienophiles give rise with fair to good regio- and diastereo
- Bloch,Chaptal-Gradoz
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p. 6147 - 6150
(2007/10/02)
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- STANNYLDIENES, NEW TOOLS FOR ORGANIC SYNTHESIS. PREPARATION AND REACTIVITY.
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Tributylstannyl-1,3-dienes could be considered synthetic equivalents of conjugated dienic anions.The preparation of differently substituted 2- and 3-trialkylstannyl-1,3-dienes is reported starting from propargyltrimethylsilane.The position of the stannyl moiety on the dienic skeleton can be controlled by hydrostannylation of (trimethylsilyl)propargyl alcohols or stannyl cupration of (trimetylsilyl)propargyl ketones.The so obtained stannyldienes are submitted to Diels Alder reaction and the corresponding cycloadducts functionalized through the C-Sn bond.Stannyldienes are also suitable for a regiocontrolled transfer of the dienic structure by : a) tin-lithium exchange and further reaction with aldehydes to give conjugated dienic alcohols; b)coupling with acyl chlorides in the presence of palladium catalysts to give conjugated dienic ketones; c) AlCl3 promoted reaction with acyl chlorides to give allenic ketones.
- Nativi, Cristina,Taddei, Maurizio,Mann, Andre
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p. 1131 - 1144
(2007/10/02)
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- The Generation and Reactions of 2-Lithiobutadiene with Aldehydes
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The tri-isopropylphenylsulphonylhydrazone of methyl vinyl ketone undergoes the Shapiro reaction to give 2-lithiobuta-1,3-diene which reacts with aldehydes to give 2-substituted dienes with high regioselectivity.
- Brown, Paul A.,Jenkins, Paul R.
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p. 1129 - 1132
(2007/10/02)
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- A Convenient Route to 2-Lithio-1,3-butadiene from Chloroprene via 2-Stannyl-1,3-butadiene
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A convenient route to 2-lithio-1,3-butadiene from chloroprene via a 2-stannyl-1,3-butadiene is presented, and the regioselective additions to a variety of carbonyl groups are demonstrated.
- Wada, Eiji,Kanemasa, Shuji,Fujiwara, Isamu,Tsuge, Otohiko
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p. 1942 - 1945
(2007/10/02)
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- THE GENERATION OF 2-LITHIO-1,3-BUTADIENE AND ITS REACTION WITH ALDEHYDES
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2-Lithio-1,3-butadiene has been generated by the Shapiro reaction.It reacts with a range of aldehydes to give 2-substituted butadienes.
- Brown, Paul A.,Jenkins, Paul R.
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p. 3733 - 3734
(2007/10/02)
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