- NiH-Catalyzed Proximal-Selective Hydroamination of Unactivated Alkenes
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Reported herein is a modular, NiH-catalyzed system capable of proximal-selective hydroamination of unactivated alkenes with diverse amine sources. The key to the successful implementation of this approach is the promotion of NiH insertion into even highly substituted olefins via coordination of the bidentate directing group to the nickel complex. A wide range of primary and secondary amines can be installed in both internal and terminal unactivated alkenes with excellent regiocontrol under the optimized reaction conditions. This protocol is flexible and general for the preparation of a variety of valuable β- and γ-amino acid building blocks that would otherwise be difficult to synthesize. The utility of this transformation was further demonstrated by the site-selective late-stage modification of complex and medicinally relevant molecules. Combined experimental and computational studies illuminate the detailed reaction mechanism.
- Jeon, Jinwon,Lee, Changseok,Seo, Huiyeong,Hong, Sungwoo
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supporting information
p. 20470 - 20480
(2020/11/27)
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- Lewis Base/Br?nsted Acid Co-Catalyzed Asymmetric Thiolation of Alkenes with Acid-Controlled Divergent Regioselectivity
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A divergent strategy for the facile preparation of various enantioenriched phenylthio-substituted lactones was developed based on Lewis base/Br?nsted acid co-catalyzed thiolation of homoallylic acids. The acid-controlled regiodivergent cyclization (6-endo vs. 5-exo) and acid-mediated stereoselective rearrangement of phenylthio-substituted lactones were explored. Experimental and computational studies were performed to clarify the origins of the regioselectivity and enantioselectivity. The calculation results suggest that C?O and C?S bond formation might occur simultaneously, without formation of a commonly supposed catalyst-coordinated thiiranium ion intermediate and the potential π–π stacking between substrate and SPh as an important factor in the enantio-determining step. Finally, this methodology was applied in the rapid syntheses of the bioactive natural products (+)-ricciocarpin A and (R)-dodecan-4-olide.
- Luo, Hui-Yun,Dong, Jia-Wei,Xie, Yu-Yang,Song, Xu-Feng,Zhu, Deng,Ding, Tongmei,Liu, Yuanyuan,Chen, Zhi-Min
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supporting information
p. 15411 - 15418
(2019/11/14)
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- Unravelling the olefin cross metathesis on solid support. Factors affecting the reaction outcome
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Olefin cross metathesis on solid support under a variety of conditions is described. A comprehensive analysis considering diverse factors governing the reaction outcome gives a series of patterns for the application of this useful methodology in organic synthesis. If the intrasite reaction is not possible, homodimerization of the soluble olefin is crucial. When the homodimer is less reactive than its monomer, reaction outcome depends on the homodimerization rate, which, in turn, depends on the precatalyst used and the reaction conditions. If the site-site interaction is a feasible process, the cross metathesis product is obtained exclusively when the newly-formed double bond is resilient to further metathetic events. Taking into account these considerations, we have demonstrated that excellent results in terms of cross metathesis coupling can be obtained under the optimized conditions, and that microwave irradiation is also an interesting alternative for the development of a practical and energy-efficient cross metathesis on solid support.
- Poeylaut-Palena, Andres A.,Mata, Ernesto G.
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scheme or table
p. 3947 - 3956
(2010/09/17)
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- Solid-phase cross-metathesis: The effect of the non-immobilized olefin and the precatalyst on the intrasite interference
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We have developed a study on the factors that influence the intrasite interactions in the cross-metathesis on solid support. When such interactions are possible, the outcome of the intrasite by-product depends on the non-immobilized olefin and the precatalyst used. The comparatively poor reactivity of first generation Grubbs precatalyst makes the easier intrasite coupling to succeed. 1.
- Poeylaut-Palena, Andres A.,Mata, Ernesto G.
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experimental part
p. 216 - 227
(2010/08/20)
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- Regio- and Stereoselective Ring Opening of ω-Alkenyllactones Using Organocopper Reagents
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New synthetic methods are described for the preparation of (E)-3, (E)-4, and (E)-5-alkenoic acids by the regio- and stereoselective ring opening of β, γ, and δ-lactones with unsaturated substituents at the ω-position using organocopper reagents such as halomagnesium diorganocuprates or Grignard reagents in the presence of copper(I) iodide.Both the organocopper reagents with primary, secondary, tertiary alkyl, and phenyl groups gave the corresponding carbon homologated alkenoic acids in good yields.Alkadienoic acids were also obtained in good yields by the reactions of ω-alkenyllactones with divinyl- and diallylcuprates.Utilizing the ring opening of β-isopropenyl-β-propiolactone, homoterpenoid carboxylic acids were easly obtained in good yields.The ring opening of β-(1-chlorovinyl)-β-propiolactone afforded 4-chloro-3-alkenoic acids which were easly transformed to 4-oxoalkanoic acids and 4-oxo-2-alkenoic acids.
- Kawashima, Masatoshi,Sato, Toshio,Fujisawa, Tamotsu
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p. 3255 - 3264
(2007/10/02)
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- SIMPLE METHODS FOR, THE SYNTHESIS OF (E)-4- AND (E)-5-ALKENOIC ACIDS BY THE SN2' TYPE REACTIONS OF γ-VINYL-γ-BUTYROLACTONE AND δ-VINYL-δ-VALEROLACTONE WITH ORGANOCOPPER REAGENTS
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γ-Vinyl-γ-butyrolactone and δ-vinyl-δ-valerolactone react regio- and stereoselectively with Grignard reagents in the presence of a copper(I) catalyst or with diorganocuprates to afford (E)-4- and (E)-5-alkenoic acids, respectively, in high yields.Synthetic utility of the former reaction is demonstrated in the simple synthesis of (4E,7Z)-4,7-tridecadienyl acetate.
- Fujisawa, Tamotsu,Sato, Toshio,Kawashima, Masatoshi,Naruse, Kouichi,Tamai, Kouichi
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p. 3583 - 3586
(2007/10/02)
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