- Rhodium-Catalyzed Remote C(sp3)?H Borylation of Silyl Enol Ethers
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A rhodium-catalyzed remote C(sp3)?H borylation of silyl enol ethers (SEEs, E/Z mixtures) by alkene isomerization and hydroboration is reported. The reaction exhibits mild reaction conditions and excellent functional-group tolerance. This method is compatible with an array of SEEs, including linear and branched SEEs derived from aldehydes and ketones, and provides direct access to a broad range of structurally diverse 1,n-borylethers in excellent regioselectivities and good yields. These compounds are precursors to various valuable chemicals, such as 1,n-diols and aminoalcohols.
- Li, Jie,Qu, Shuanglin,Zhao, Wanxiang
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supporting information
p. 2360 - 2364
(2020/01/02)
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- Enantioselective redox-relay oxidative heck arylations of acyclic alkenyl alcohols using boronic acids
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A general, highly selective asymmetric redox-relay oxidative Heck reaction using achiral or racemic acyclic alkenols and boronic acid derivatives is reported. This reaction delivers remotely functionalized arylated carbonyl products from acyclic alkenol substrates, with excellent enantioselectivity under mild conditions, bearing a range of useful functionality. A preliminary mechanistic investigation suggests that the regioselectivity of the initial migratory insertion is highly dependent on the electronic nature of the boronic acid and more subtle electronic effects of the alkenyl alcohol.
- Mei, Tian-Sheng,Werner, Erik W.,Burckle, Alexander J.,Sigman, Matthew S.
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supporting information
p. 6830 - 6833
(2013/06/05)
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- Addition reaction of arylboronic acids to aldehydes and α,β-unsaturated carbonyl compounds catalyzed by conventional palladium complexes in the presence of chloroform
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Arylboronic acids react with aldehydes and α,β-unsaturated carbonyl compounds in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding addition products in good yields, and chiral benzhydrol was obtained with up to 43% e.e. using (S,S)-bppm as a ligand. General palladium complexes have no catalytic activity without chloroform. Because chloroform is essential for this reaction, these reactions would be promoted by dichloromethylpalladium(II) species.
- Yamamoto, Tetsuya,Iizuka, Michiko,Takenaka, Hiroto,Ohta, Tetsuo,Ito, Yoshihiko
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experimental part
p. 1325 - 1332
(2009/09/28)
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- Nickel-catalyzed conjugate addition of arylboron reagents to α,β-unsaturated carbonyl compounds with the aid of a catalytic amount of an alkyne
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Alkynes in combination with a catalytic amount of a nickel complex were found to catalyze the conjugate addition of arylboron reagents to α,β-unsaturated carbonyl compounds, where use of an optically active alkyne induces the asymmetric addition. Copyright
- Shirakawa, Eiji,Yasuhara, Yuichi,Hayashi, Tamio
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p. 768 - 769
(2007/10/03)
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- Palladium-catalyzed enantioselective conjugate addition of arylboronic acids
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(Chemical Equation Presented) The first asymmetric palladium-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated aldehydes, ketones, and esters is described. For cyclic substrates, excellent chemo-, regio-, and enantioselectivities are achieved when a Pd(O2CCF 3)2/DuPHOS catalyst is applied.
- Gini, Francesca,Hessen, Bart,Minnaard, Adriaan J.
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p. 5309 - 5312
(2007/10/03)
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- Conjugate addition of aryl boronic acids to enones catalyzed by cationic palladium(II)-phosphane complexes
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A cationic palladium complex was found to be an efficient catalyst for the 1,4-addition of aryl boronic acids to enones at room temperature (see scheme; X= ClO4, OTf, BF4, PF6, or SbF6); Tf=trifluoromethanesulfonyl).
- Nishikata, Takashi,Yamamoto, Yasunori,Miyaura, Norio
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p. 2768 - 2770
(2007/10/03)
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- 1,4-Addition of Arylsiloxanes to Enones Catalyzed by Dicationic Palladium(II) Complexes in Aqueous Media
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Catalytic 1,4-addition of arylsiloxanes to enones was carried out at 75°C in the presence of a dicationic palladium(II) catalyst in aqueous 1,4-dioxane. A nitrile-free complex generated in situ from Pd(dba)2 and Cu(BF4)2 in the presence of dppe or dppben was recognized to be the best catalyst to achieve high yields for the representative enones and enals.
- Nishikata, Takashi,Yamamoto, Yasunori,Miyaura, Norio
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p. 752 - 753
(2007/10/03)
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- Palladium-catalyzed conjugate addition of organosiloxanes to α,β-unsaturated carbonyl compounds and nitroalkenes
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The addition of aryltrialkoxysilanes to α,β-unsaturated carbonyl compounds (ketones, aldehydes) and nitroalkenes in the presence of SbCl3, TBAF, AcOH, and a catalytic amount of Pd(OAc)2, in CH3CN at 60 °C, provides the corresponding conjugate addition products in moderate to good yields. The addition of equimolar amounts of SbCl3 and TBAF is necessary for this reaction to proceed smoothly. The arylpalladium complex, which is generated by the transmetalation from a putative hypercoordinate silicon compound, is considered to be the catalytically active species.
- Denmark, Scott E.,Amishiro, Nobuyoshi
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p. 6997 - 7003
(2007/10/03)
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- Palladium(II)-Catalyzed Conjugate Addition of Aromatics to α,β-Unsaturated Ketones and Aldehydes with Arylantimony Compounds
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Triarylstibines react with α,β-unsaturated ketones and aldehydes in acetic acid at room temperature in the presence of AgOAc and a catalytic amount of Pd(OAc)2 to afford the conjugate addition products (the formal hydroarylated compounds to an olefinic part) in good yields. In contrast, diarylantimony chlorides, arylantimony dichlorides, and diphenylantimony acetate react with the enones and enals even in the absence of AgOAc to afford the same products in higher yields compared with those from triarylstibines. These are new C-C bond-forming reactions using arylantimony(III) compounds in which the formation of a palladium enolate or a trivalent antimony enolate is proposed as an intermediate.
- Cho, Chan Sik,Motofusa, Shin-Ichi,Ohe, Kouichi,Uemura, Sakae
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p. 2341 - 2348
(2007/10/03)
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- A New Catalytic Activity of Antimony(III) Chloride in Palladium(0)-Catalyzed Conjugate Addition of Aromatics to α,β-Unsaturated Ketones and Aldehydes with Sodium Tetraphenylborate and Arylboronic Acids
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A remarkable catalytic effect of antimony(III) chloride is disclosed in palladium(0)-catalyzed conjugate addition of aromatics to α,β-unsaturated ketones and aldehydes with sodium tetraphenylborate and arylboronic acids in acetic acid at 25 deg C.Several other metal chlorides such as AlCl3, SnCl4, AsCl3, TiCl4, FeCl3, MoCl5, and CeCl3 are also effective in some cases, but SbCl3 is the salt of choice.Two key steps are proposed for this reaction: one is the oxidative addition of a C-B bond to Pd(0) forming an arylpalladium species, and the other is the formation of an antimony enolate derived from the initial coordination of SbCl3 to the carbonyl oxygen of an organopalladium intermediate.
- Cho, Chan Sik,Motofusa, Shin-ichi,Ohe, Kouichi,Uemura, Sakae,Shim, Sang Chul
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p. 883 - 888
(2007/10/02)
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- Palladium(II)-catalyzed hydroarylation of α,β-unsaturated aldehydes and ketones with triarylstibines in the presence of silver acetate
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Triarylstibines react with α,β-unsaturated aldehydes and ketones in acetic acid at 25°C in the presence of silver acetate and a catalytic amount of palladium(II) acetate to afford the hydroarylation products by conjugate addition in good yields.
- Cho, Chan Sik,Tanabe, Koichiro,Uemura, Sakae
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p. 1275 - 1278
(2007/10/02)
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- Antimony(III) chloride as an efficient catalyst for palladium-catalyzed hydrophenylation of α,β-unsaturated ketones and aldehydes
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A remarkable catalytic effect of antimony(III) chloride was disclosed in palladium-catalyzed hydrophenylation of α,β-unsaturated ketones and aldehydes (Michael-type conjugate addition) with sodium tetraphenylborate in acetic acid at 25°C.
- Cho, Chan Sik,Motofusa, Shin-Ichi,Uemura, Sakae
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p. 1739 - 1742
(2007/10/02)
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- SONOCHEMICALLY PREPARED ORGANOZINC REAGENTS. CONJUGATE ADDITIONS TO α-β UNSATURATED ALDEHYDES
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Organozinc reagents, prepared by sonication from organic halides, lithium and zinc bromide, add conjugatively to α-enals in the presence of nickel acetylacetonate.Satisfactory yields are obtained from arylbromides.
- Barboza, Jayne Carlos de Souza,Petrier, Christian,Luche, Jean-Louis
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p. 829 - 830
(2007/10/02)
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