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- Afewerki, Samson, et al.
(author)
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Direct Regiospecific and Highly Enantioselective Intermolecular α-Allylic Alkylation of Aldehydes by a Combination of Transition-Metal and Chiral Amine Catalysts
- 2012
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In: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 18:10, s. 2972-2977
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Journal article (peer-reviewed)abstract
- The first direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.
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- Ibrahem, Ismail, et al.
(author)
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One-pot three-component catalytic asymmetric synthesis of homoallylboronates
- 2012
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In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY. Vol 243. - : American Chemical Society (ACS). ; , s. 889-INOR-
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Conference paper (peer-reviewed)abstract
- 1. A novel one-pot three-component catalytic enantioselective reaction between bis(pinacolato)diboron, enals and 2-(triphenylphosphoranylidene)acetate esters employing inexpensive bench stable Cu salts and simple chiral amine as co-catalysts is presented. The reaction proceeds via a tandem catalytic asymmetric conjugate borane addition/Wittig sequence where the b-boration step is 1,4-selective and gives the corresponding homoallylboronate products with high enantiomeric ratios (up to 97.5:2.5 er).2. The direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by combination of achiral bench stable Pd(0) complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 er). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals and 2-alkyl-butane-1,4-diols.
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