- Desulfurizative titanation of allyl sulfides. Regio and diastereoselective preparation of homoallyl alcohols
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The successive treatments of allyl sulfides with the low-valent organotitanium species, prepared by the reaction of tianocene dichloride with 2 equiv. of butyllithium, and aldehydes gave the homoallyl alcohols with high regio and diastereoselectivity in good yields.
- Takeda, Takeshi,Miura, Ichiro,Horikawa, Yasuo,Fujiwara, Tooru
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Read Online
- Generation of allylic titanocene derivatives from vinyl halides and a Cp2TiCl2-Me3Al reagent system
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The reagent prepared in advance by stirring a mixture of a Cp2TiCl2-Me3Al reagent system in the ratio of 1 : 4 in toluene for 3 days is found to be effective in generating allylic titanocene on treatment with vinyl halides in THF.
- Hanzawa, Yuji,Kowase, Noboru,Taguchi, Takeo
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Read Online
- Catalytic Nucleophilic Allylation Driven by the Water-Gas Shift Reaction
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The ruthenium-catalyzed allylation of aldehydes with allylic pro-nucleophiles has been demonstrated to be an efficient means to form carbon-carbon bonds under mild conditions. The evolution of this reaction from the initial serendipitous discovery to its general synthetic scope is detailed, highlighting the roles of water, CO, and amine in the generation of a more complete catalytic cycle. The use of unsymmetrical allylic pro-nucleophiles was shown to give preferential product formation through the modulation of reaction conditions. Both (E)-cinnamyl acetate and vinyl oxirane were efficiently used to form the anti-branched products (up to >20:1 anti/syn) and E-linear products (up to >20:1 E/Z) in high selectivity with aromatic, α,β-unsaturated, and aliphatic aldehydes, respectively. Attempts to render the reaction enantioselective are highlighted and include enantioenrichment of up to 75:25 for benzaldehyde.
- Denmark, Scott E.,Matesich, Zachery D.,Nguyen, Son T.,Milicevic Sephton, Selena
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- Chelation versus Non-Chelation Control in the Stereoselective Alkenyl sp2 C?H Bond Functionalization Reaction
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A hydroxy group chelation-assisted stereospecific oxidative cross-coupling reaction between alkenes was developed under mild reaction conditions. In the presence of palladium catalyst, the alkenes tethered with hydroxy functionality can couple efficiently with electron-deficient alkenes to form the corresponding multi-substituted olefin products. The hydroxy group on the substrate could play dual roles in reaction, acting as the directing group for alkenyl C?H bond activation and controlling the stereoselectivity of the products.
- Liang, Qiu-Ju,Yang, Chao,Meng, Fei-Fan,Jiang, Bing,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 5091 - 5095
(2017/04/24)
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- Manganese-Promoted Oxidative Cyclization of Unsaturated Oximes Using Molecular Oxygen in Air under Ambient Conditions
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A highly efficient manganese-promoted oxidative cyclization of unsaturated oximes to afford the corresponding 4,5-dihydroisoxazoline alcohols was developed. A very low loading (generally 0.1–0.2 mol-%) of Mn(acac)3(acac = acetylacetonate) promoted the oxidative cyclization through the direct incorporation of molecular oxygen present in air (open flask) at room temperature.
- Yamamoto, Daisuke,Oguro, Takuto,Tashiro, Yuuki,Soga, Masayuki,Miyashita, Kazuhito,Aso, Yoshiaki,Makino, Kazuishi
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supporting information
p. 5216 - 5219
(2016/11/13)
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- Synthesis and reactivity of 1,2-dioxolanes from β,γ-epoxy ketones
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Five-membered ring peroxides were prepared in one step in 31-86% yield from readily accessible β,γ-epoxy ketones and H2O2. The reaction proceeded via a tetrahydrofuran, which was converted to the thermodynamically favored 1,2-dioxola
- Kandur, Wynne V.,Richert, Kathleen J.,Rieder, Curtis J.,Thomas, Andrew M.,Hu, Chunhua,Ziller, Joseph W.,Woerpel
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supporting information
p. 2650 - 2653
(2014/06/09)
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- Hydroxyl-directed stereoselective diboration of alkenes
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An alkoxide-catalyzed directed diboration of alkenyl alcohols is described. This reaction occurs in a stereoselective fashion and is demonstrated with cyclic and acyclic homoallylic and bishomoallylic alcohol substrates. After oxidation, the reaction generates 1,2-diols such that the process represents a method for the stereoselective directed dihydroxylation of alkenes.
- Blaisdell, Thomas P.,Caya, Thomas C.,Zhang, Liang,Sanz-Marco, Amparo,Morken, James P.
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supporting information
p. 9264 - 9267
(2014/07/21)
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- Catalytic, nucleophilic allylation of aldehydes with 2-substituted allylic acetates: Carbon-carbon bond formation driven by the water-gas shift reaction
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The ruthenium-catalyzed allylation of aldehydes with allylic acetates has been expanded to incorporate substituents at the 2-position of the allylic components. Allylic acetates bearing a variety of substituents (CO 2-t-Bu, COMe, Ph, CH(OEt)su
- Denmark, Scott E.,Matesich, Zachery D.
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p. 5970 - 5986
(2014/07/21)
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- Palladium-catalyzed cross-coupling of unactivated alkenes with acrylates: Application to the synthesis of the C13-C21 fragment of palmerolide A
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Diene to meet: A palladium-catalyzed cross-coupling reaction between alkyl-substituted olefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom-economical reaction, which forms C sp 2-C sp 2 bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the C13-C21 fragment of palmerolide A.
- Wen, Zhen-Kang,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 13284 - 13287,4
(2012/12/12)
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- Palladium-catalyzed cross-coupling of unactivated alkenes with acrylates: Application to the synthesis of the C13-C21 fragment of palmerolide A
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Diene to meet: A palladium-catalyzed cross-coupling reaction between alkyl-substituted olefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom-economical reaction, which forms C sp 2-C sp 2 bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the C13-C21 fragment of palmerolide A.
- Wen, Zhen-Kang,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 13284 - 13287
(2013/01/15)
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- Stereoselective synthesis of the C9-C19 fragment of lyngbyaloside B and C via ether transfer
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A stereoselective synthesis of the C9-C19 fragment of lyngbyaloside B and C highlighted, by an extension of our ether transfer methodology, enables the formation of tertiary ethers. 2-Naphthylmethyl ethers have been shown to proceed efficiently through ether transfer with high stereoselectivity and are easily deprotected by DDQ oxidation. Variation of the workup conditions results in the stereoselective formation of syn-1,3-diol mono- or diethers.
- Stefan, Eric,Taylor, Richard E.
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supporting information; experimental part
p. 3490 - 3493
(2012/08/13)
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- Synthesis of hetero- and carbocycles by nucleophilic substitution at sp2 carbon
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Vinylic halides having alcohol, sulfonamide, active methine, and thiol moieties as nucleophiles cyclize to hetero- and carbocycles by intramolecular nucleophilic substitution at the sp2 carbon centers. The density functional theory calculations suggest that the cyclization proceeds through SN2-type substitution (the in-plane vinylic nucleophilic substitution, SNVσ), when vinyl halides are substituted with oxygen, nitrogen, and carbon nucleophiles. The substitution with sulfur nucleophiles, in contrast, proceeds through both routes of SNVσ and out-of-plane vinylic nucleophilic substitution (SNVπ).
- Miyauchi, Hironori,Chiba, Shunsuke,Fukamizu, Koji,Ando, Kaori,Narasaka, Koichi
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p. 5940 - 5953
(2008/02/03)
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- Chiral phosphine oxide BINAPO as a catalyst for enantioselective allylation of aldehydes with allyltrichlorosilanes
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The effectiveness of chiral phosphine oxide BINAPO as a catalyst for the enantioselective addition of allyltrichlorosilanes to aldehydes was demonstrated, wherein the combination of diisopropylethylamine and tetrabutylammonium iodide as additives is cruci
- Nakajima, Makoto,Kotani, Shunsuke,Ishizuka, Tadao,Hashimoto, Shunichi
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p. 157 - 159
(2007/10/03)
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- Direct preparation of allylic indium(III) reagents from allylic alcohols via a reductive transmetalation of π-allylnickel(II) with indium(I) iodide
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InI-mediated direct allylation of carbonyl compounds with allylic alcohols proceeded smoothly with catalytic amounts of Ni(acac)2 and PPh 3 to give the corresponding homoallylic alcohols in high yields. Allylindium compounds were shown to be the real allylating agents in the present system. Substituted allylic alcohols gave branched homoallylic alcohols with syn-selectivity irrespective of the geometry of the starting allylic alcohols, whereas high anti-selectivity was observed when a bulky substituent is present in the allylic alcohols. The outcome of the diastereoselectivity is discussed on the basis of the reaction mechanism, comparing with the corresponding Pd-catalyzed version. Another distinct behavior between the Ni- and Pd-catalyzed allylation was demonstrated in the reaction of hex-1,5-diene-3,4-diol derivatives: the Pd catalyst did not give any coupling product, whereas the Ni-catalyzed InI-mediated reaction with benzaldehyde afforded the 1:1 and 1:2 adduct diols selectively depending on the reaction conditions.
- Hirashita, Tsunehisa,Kambe, Shinya,Tsuji, Hiromitsu,Omori, Hideki,Araki, Shuki
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p. 5054 - 5059
(2007/10/03)
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- Scandium-catalyzed allylboration of aldehydes as a practical method for highly diastereo- and enantioselective construction of homoallylic alcohols
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A general approach for the allylation of aldehydes using stable, air-tolerant camphor-based chiral allylboronates under Sc(OTf)3 catalysis is described. This practical methodology provides both syn and anti propionate units and other homoallylic alcohols with very high levels of diastereo- and enantioselectivity for several substrates, including functionalized aliphatic aldehydes useful toward the elaboration of complex natural products. Copyright
- Lachance, Hugo,Lu, Xiaosong,Gravel, Michel,Hall, Dennis G.
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p. 10160 - 10161
(2007/10/03)
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- 'Halophilic activation' of chlorosilanes: Allylation of aldehydes catalyzed by platinum dichloride or silver triflate
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PtCl2, AgOTf or Hg(CF3CO2)2 (1-5 mol%) efficiently catalyze the addition of allyldimethylchlorosilane to aldehydes. The reaction is highly aldehyde selective, leaving ketones, esters, nitriles, alkenes, aryl hal
- Fuerstner, Alois,Voigtlaender, David
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p. 959 - 969
(2007/10/03)
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- A Cp2TiCl2-Me3Al (1:4) reagent system: An efficient reagent for generation of allylic titanocene derivatives from vinyl halides, vinyl ethers and carboxylic esters
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The reagent prepared in advance by stirring a mixture of a Cp'2TiCl2- Me3Al (a 1:4 ratio) reagent system in toluene for 3 days is found to be effective in generating allylic titanocene on treatment with vinyl halides, vinyl ethers and carboxylic esters in THF. The process for the generation of an allylic titanocene species from these starting materials was suggested to proceed through a formation of titanacyclobutane and the subsequent elimination of the halogen or alkoxyl group. The generated allylic titanocene intermediate was proved to be an allylic Ti(IV) species and showed the typical reactivity to carbonyl compounds.
- Hanzawa, Yuji,Kowase, Noboru,Momose, Shu-Ichi,Taguchi, Takeo
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p. 11387 - 11398
(2007/10/03)
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- Facile and Highly Stereoselective Synthesis of Homoallylic Alcohols Using Organosilicon Intermediates
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Allyltrichlorosilanes regioselectively reacted with aldehydes in N,N-dimethylformamide (DMF) without a catalyst to afford the corresponding homoallylic alcohols in high yields.The reactions proceeded under neutral conditions, and syn- and anti-homoallylic alcohols were stereoselectively obtained from (Z)- and (E)-allyltrichlorosilanes, respectively.In these reactions, DMF coordinated to the silicon atom of the allyltrichlorosilanes to form hypervalent silicates, which in turn reacted with aldehydes smoothly.Solvent effects in these reactions were also examined.The reactions were applied to the one-pot synthesis of homoallylic alcohols from allylic chlorides via organosilicon intermediates.While syn-homoallylic alcohols were prepared from (Z)-allyl chlorides, anti-homoallylic alcohols were obtained from (E)-allyl chlorides.Unique regioselectivities in the reactions of 1-chloro-2,4-pentadiene were also found.Finally, the one-pot synthesis of homoallylic alcohols from 1,3-dienes is reported.
- Kobayashi, Shu,Nishio, Koichi
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p. 6620 - 6628
(2007/10/02)
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- Iodine(III)-Mediated Intramolecular Cyclization of Hydroxy Allylsilanes: Synthesis of 5- or 6-Membered β-Methylene Cyclic Ethers
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Oxidative cyclization of hydroxy allylsilanes utilizing the combination of a hypervalent organoiodine compound and a Lewis acid was studied.The allylsilanes 4, prepared from the γ-lactones 1 via conversion to the bis(trimethylsilylmethyl)carbinols 3, on t
- Ochiai, Masahito,Fujita, Eiichi,Arimoto, Masao,Yamaguchi, Hideo
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p. 989 - 997
(2007/10/02)
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- Hypervalent Organoiodine Chemistry: a New Synthesis of β-Methylene Cyclic Ethers
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The allylsilanes (1), containing suitably-substituted hydroxy-groups, on treatment with iodosylbenzene in the presence of BF3-Et2O in an ether solvent, give 5- or 6-membered β-methylene cyclic ethers (3) in good yields, presumably via the highly reactive
- Ochiai, Masahito,Fujita, Eiichi,Arimoto, Masao,Yamaguchi, Hideo
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p. 1108 - 1109
(2007/10/02)
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