- Ni0-catalyzed regio- and stereoselective coupling reaction of Me3B, isoprene, and aldehydes
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In the presence of Ni(acac)2 (0.1 equiv.), the three components of trimethylborane, isoprene, find aromatic and aliphatic aldehydes' combine to produce 1-substituted 3-methyl-3-hexenols (3) in good yield and with high regio- and stereoselectivity (E:Z > 13:1). (C) 2000 Elsevier Science Ltd.
- Kimura,Shibata,Koudahashi,Tamaru
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- Ni-Catalyzed 1,2-Diarylation of Alkenyl Ketones: A Comparative Study of Carbonyl-Directed Reaction Systems
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A nickel-catalyzed 1,2-diarylation of alkenyl ketones with aryl iodides and arylboronic esters is reported. Ketones with a variety of substituents serve as effective directing groups, offering high levels of regiocontrol. A representative product is diversified into a wide range of useful products that are not readily accessible via existing 1,2-diarylation reactions. Preliminary mechanistic studies shed light on the binding mode of the substrate, and Hammett analysis reveals the effect of electronic factors on initial rates.
- Apolinar, Omar,Derosa, Joseph,Engle, Keary M.,Karunananda, Malkanthi K.,Kleinmans, Roman,Li, Zi-Qi,Tran, Van T.,Wisniewski, Steven R.
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supporting information
p. 5311 - 5316
(2021/07/26)
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- Selective Isomerization of Terminal Alkenes to (Z)-2-Alkenes Catalyzed by an Air-Stable Molybdenum(0) Complex
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Positional and stereochemical selectivity in the isomerization of terminal alkenes to internal alkenes is observed using the cis-Mo(CO)4(PPh3)2 precatalyst. A p-toluenesulfonic acid (TsOH) cocatalyst is essential for catalyst activity. Various functionalized terminal alkenes have been converted to the corresponding 2-alkenes, generally favoring the Z isomer with selectivity as high as 8:1 Z:E at high conversion. Interrogation of the catalyst initiation mechanism by 31P NMR reveals that cis-Mo(CO)4(PPh3)2 reacts with TsOH at elevated temperatures to yield a phosphine-ligated Mo hydride (MoH) species. Catalysis may proceed via 2,1-insertion of a terminal alkene into a MoH group and stereoselective β-hydride elimination to yield the (Z)-2-alkene.
- Becica, Joseph,Glaze, Owen D.,Wozniak, Derek I.,Dobereiner, Graham E.
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p. 482 - 490
(2018/02/17)
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- Nickel-catalyzed addition of dimethylzinc to aldehydes across alkynes and 1,3-butadiene: An efficient four-component connection reaction
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In the presence of 10 mol % of Ni(acac)2, four components comprising Me2Zn, alkynes, 1,3-butadiene, and carbonyl compounds combine in this order in 1:1:1:1 ratio to furnish (3E,6Z)-octadien-1-ols 1 in good yields. Similarly, the coupling reaction of Me2Zn, 1,ω-dienynes 5, and carbonyls furnishes 1-alkylidene-2-(4′-hydroxy- (1′E)-alkenyl)cyclopentanes and -cyclohexanes 6 and their oxygen and nitrogen heterocycle derivatives in good yield and an excellent level of 1,5-diastereoselectivity with respect to the cycloalkane methine carbon and the OH-bearing carbon of the C2 side chain. The reaction is completed in most cases within 1 h at room temperature under nitrogen, tolerates an ester, a hydroxy, an allyl and propargyl ethers, an allylamino, and a pyridyl functionalities, and accommodates a variety of aromatic and aliphatic alkynes and carbonyls (aldehydes and ketones).
- Kimura, Masanari,Ezoe, Akihiro,Mori, Masahiko,Tamaru, Yoshinao
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p. 201 - 209
(2007/10/03)
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- Nickel(0)-catalyzed three-component connection reaction of dimethylzinc, 1,3-dienes, and carbonyl compounds
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Linear 1:1:1 coupling of dimethylzinc, 1,3-dienes, and carbonyl compounds in this order is facilitated by catalytic amounts of [Ni(acac)2] to give (E)-3-hexen-1-ols in good yields under mild conditions [Eq. (a)]. Increasing steric hindrance at the carbonyl group favors formation of the 1:2:1 adduct, and this is the sole product when the carbonyl compound is acetone, acac = acetylacetonate.
- Kimura, Masanari,Matsuo, Shintaro,Shibata, Kazufumi,Tamaru, Yoshinao
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p. 3386 - 3388
(2007/10/03)
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- Reaction of 1,3-dihalopropene with trialkylmanganate
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A three-component coupling reaction was performed. Treatment of 1,3-dibromopropene or 1,3-dichloropropene with tributylmanganate (n-Bu3MnLi) provided a butylated allylmanganese compound which could be trapped by an electrophile such as benzalde
- Kakiya, Hirotada,Inoue, Rie,Shinokubo, Hiroshi,Oshima, Koichiro
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- Benzotriazole-mediated [2,3]-wittig rearrangement. General and stereocontrolled syntheses of homoallyl alcohols and β,γ-unsaturated ketones
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Readily accessible allyl 1-(benzotriazol-1-yl)alkyl ethers (13 and 19), upon treatment with 2.5 equiv of nucleophilic lithium reagents, give secondary and tertiary homoallyl alcohols (16 and 21), respectively, exclusively in the E configuration in excellent yields. This is achieved by deprotonation followed by [2,3]-Wittig rearrangement, departure of the benzotriazolyl group, and then nucleophilic addition to the resulting carbonyl compound. Following a similar protocol, primary E-homoallyl alcohols 18 are prepared in good yield by the reaction of ethers 13 with LDA in the presence of NaBH4. Our approach complements the stereochemical Z-selective syntheses of primary homoallyl alcohols of Still and of Bruckner. Wittig rearrangement of the anions of 19 generated with LDA analogously furnishes E-β,γ-unsaturated ketones 20 in excellent yields.
- Katritzky, Alan R.,Wu, Hong,Xie, Linghong
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p. 4035 - 4039
(2007/10/03)
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- α-Regioselective and Stereospecific Addition of Allylic Tins to Aldehydes via Photoinduced Electron Transfer
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(E)- and (Z)-Allylic tributyltins add to aromatic aldehydes to afford regioreversed α-adduct predominantly with almost complete retention of the stereochemistry of the allylic groups under photochemical conditions.The photoinduced single electron transfer mechanism is proposed.
- Takuwa, Akio,Shiigi, Junji,Nishigaichi, Yutaka
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p. 3457 - 3460
(2007/10/02)
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- One-Pot Synthesis of Substituted Homoallylic Alcohols (3-Alkenols) and 1-Deuterio-3-alkenols; II. Extension to Ketone Enolates
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The reaction of different lithium ketone enolates with α-chloro carbonyl compounds followed by in situ reduction with lithium aluminium hydride or deuteride and final lithiation with lithium powder leads to the corresponding homoallylic or 1-deuterio homoallylic alcohols in a regioselective manner.
- Barluenga, Jose,Alvarez, Flora,Concellon, Jose M.,Bernad, Pablo,Yus, Miguel
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p. 318 - 320
(2007/10/02)
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- Stereoselective Synthesis of Alcohols, XXII. E/Z-Selectivity on Addition of α-Substituted Allylboronates to Aldehydes
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α-Heterosubstituted allylboronates 7 are prepared.Addition of 7 to aldehydes results in E/Z-isomeric homoallyl alcohols 13 and 14.The reasons for the predominant formation of the Z-isomer 14 are discussed.The Z-bromo olefins 16 and 20 obtained in this way serve as starting point for chain extension or formation of δ-lactones 21.
- Hoffmann, Reinhard W.,Landmann, Bernd
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p. 1039 - 1053
(2007/10/02)
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- Selective Synthesis of either Branched or Linear Homoallyl Alcohols via the Reaction of Aldehydes with the Allylic Borane-Selenium System
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Either branched (2) or linear (3) homoallyl alcohols can be prepared independently by choosing the reaction conditions through the reaction of (phenylselenyl)allyl carbanion with trialkylboranes.
- Yamamoto, Yoshinori,Saito, Yoshikazu,Maruyama, Kazuhiro
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p. 5408 - 5409
(2007/10/02)
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