- Asymmetric Multicomponent Reactions for Efficient Construction of Homopropargyl Amine Carboxylic Esters
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Developing an efficient and highly enantioselective protocol to access homopropargyl amines is of high interest to the synthetic community and also remains a formidable challenge for organic chemists. Here, we present integrated Rh2(OAc)4- and BINOL-derived chiral phosphoric acid cooperatively catalyzed three-component reactions of alkynyldiazoacetates, imines with various nucleophiles including alcohols, indoles, and N,N-disubstituted anilines, affording the corresponding homopropargyl amines containing two vicinal chiral centers in satisfactory yields with high to excellent diastereo- and enantioselectivities.
- Yu, Sifan,Hua, Ruyu,Fu, Xiang,Liu, Gengxin,Zhang, Dan,Jia, Shikun,Qiu, Huang,Hu, Wenhao
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- A Stereospecific Access to Allylic Systems Using Rhodium(II)-Vinyl Carbenoid Insertion into Si-H, O-H, and N-H Bonds
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Rhodium-catalyzed decomposition of α-vinyldiazoesters in the presence of silanes, alcohols, ethers, amines, and thiols have been shown to produce the corresponding α-silyl, α-hydroxy, α-alkoxy, α-amino, and α-thioalkoxy esters in generally good yield with a complete retention of the stereochemistry of the double bond of the diazo precursor. An extension of the process in homochiral series has also been devised using either a chiral auxiliary attached to the ester function or achiral α-vinyldiazoesters and Doyle's chiral catalyst Rh2(MEPY)4. In the former approach, pantolactone as chiral auxiliary gave diastereoselectivities of up to 70%, while the second approach produced the desired allylsilane with ee as high as 72%. On the other hand, Rh2(MEPY)4-catalyzed insertion into the O-H bond of water led to poor or no enantioselectivity in good agreement with recent literature reports.
- Bulugahapitiya, Priyadarshanie,Landais, Yannick,Parra-Rapado, Liliana,Planchenault, Denis,Weber, Valery
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p. 1630 - 1641
(2007/10/03)
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- Rhodium(II)-vinylcarbenoid insertion into the Si - H bond. A new stereospecific synthesis of allylsilanes
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Rh2(OAc)4 catalysed decomposition of vinyldiazocarbonyl compounds in the presence of organosilanes led stereospecifically to the corresponding allylsilanes in good yields. An asymmetric approach has also been considered as well as the extension of the methodology to the synthesis of other allylic systems.
- Landais, Yannick,Planchenault, Denis,Weber, Valery
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p. 9549 - 9552
(2007/10/02)
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