- Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes
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The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.
- Huang, Jiaxin,Li, Jie,Yang, Wen,Zhang, Kezhuo,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 302 - 305
(2022/01/03)
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- Copper Hydride Catalyzed Reductive Claisen Rearrangements
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An efficient reductive Claisen rearrangement, catalyzed by in situ generated copper hydride and stoichiometric in diethoxymethylsilane, has been developed. Yields of up to 95 ;% with good to excellent diastereoselectivities were observed in this reaction. Mechanistic studies showed that the stereospecific rearrangement proceeded via a chair transition state of (E)-silyl ketene acetals as intermediates and not via the copper enolates.
- Wong, Kong Ching,Ng, Elvis,Wong, Wing-Tak,Chiu, Pauline
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supporting information
p. 3709 - 3712
(2016/03/08)
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- Organoselenium-catalyzed, hydroxy-controlled regio- and stereoselective amination of terminal alkenes: Efficient synthesis of 3-amino allylic alcohols
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An efficient route to prepare 3-amino allylic alcohols in excellent regio- and stereoselectivity in the presence of bases by orangoselenium catalysis has been developed. In the absence of bases α,β-unsaturated aldehydes were formed in up to 97% yield. Control experiments reveal that the hydroxy group is crucial for the direct amination.
- Deng, Zhimin,Wei, Jialiang,Liao, Lihao,Huang, Haiyan,Zhao, Xiaodan
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supporting information
p. 1834 - 1837
(2015/04/27)
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- Catalyst versus substrate induced selectivity: Kinetic resolution by palladacycle catalyzed allylic imidate rearrangements
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Making chairs: A kinetic resolution of allylic imidates by planar chiral palladacycles is described which is the result of high face selectivity for olefin coordination to the catalyst and inherent substrate selectivity. These studies confirm that planar chiral palladacycles mainly operate via (half)chair-like transition states/intermediates.
- Peters, Rene,Xin, Zhuo-Qun,Maier, Frank
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supporting information; experimental part
p. 1770 - 1774
(2011/03/23)
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- Chemoselective conjugate reduction of α,β-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media
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Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C-O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C-O to C-C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones. Now we have found that a variety of α,β-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.
- Li, Xuefeng,Li, Liangchun,Tang, Yuanfu,Zhong, Ling,Cun, Linfeng,Zhu, Jin,Liao, Jian,Deng, Jingen
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supporting information; experimental part
p. 2981 - 2988
(2010/07/05)
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- Catalyzed Metalation Applied to 2-Methoxypyridine
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Directed ortho lithiation of 2-methoxypyridine (1) has been regioselectively achieved at position 3 by using methyllithium catalyzed by a small amount of diisopropylamine.This metalation methodology, called "catalyzed metalation", gave good results whereas other metalation routes failed.This allowed the convenient synthesis of various 3-substituted 2-methoxypyridines of general interest.
- Trecourt, F.,Mallet, M.,Marsais, F.,Queguiner, G.
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p. 1367 - 1371
(2007/10/02)
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- Stereospecific hydroxylation of chiral allylic β-hydroxysulfoxides: asymmetric synthesis of L-arabinitol
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Chiral allylic β-hydroxysulfoxides 2 have been hydroxylated by the osmium tetroxide catalyzed reaction.The reaction can be highly stereoselective depending on the nature of the substituent linked to the double bond and the configurations of the sulfoxide and hydroxylic groups.The diastereoselectivity can be as high as 90 percent.This methodology was applied to the asymmetric synthesis of L-arabinitol.
- Solladie, Guy,Frechou, Catherine,Hutt, Jean,Demailly, Gilles
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p. 827 - 836
(2007/10/02)
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