- Preparation method of chiral 1, 4-diphenyl-2-hydroxy-1, 4-dibutanone compound
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The invention provides a preparation method of a chiral 1, 4-diphenyl-2-hydroxyl-1, 4-dibutanone compound. The method comprises the following steps: in the presence of a chiral metal compound, mixing silyl enol ether and phenylacetaldehyde monohydrate or substituted phenylacetaldehyde monohydrate in a solvent and performing action to obtain the chiral 1, 4-diphenyl-2-hydroxy-1, 4-dibutanone compound, wherein the reaction equation is as shown in the formula 1; R1 of silyl enol ether is of a phenyl or furan structure, a substituent R2 in substituted phenyl glyoxal monohydrate is selected from one or more of hydrogen atoms, halogen, methyl, methoxyl, nitryl and trifluoromethyl, and the substituent is at the ortho-position, meta-position or para-position of a benzene ring. The chiral metal compound can efficiently and highly enantioselectively catalyze the asymmetric Mukaiyama aldol reaction of the phenylacetaldehyde monohydrate compound, a new method for synthesizing the 1, 4-diphenyl-2-hydroxy-1, 4-dibutanone compound is provided, the problem that conditions are harsh in the original reaction is solved, and the chiral metal compound is more environmentally friendly.
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- Towards a General Understanding of Carbonyl-Stabilised Ammonium Ylide-Mediated Epoxidation Reactions
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The key factors for carbonyl-stabilised ammonium ylide-mediated epoxidation reactions were systematically investigated by experimental and computational means and the hereby obtained energy profiles provide explanations for the observed experimental results. In addition, we were able to identify the first tertiary amine-based chiral auxiliary that allows for high enantioselectivities and high yields for such epoxidation reactions.
- Novacek, Johanna,Roiser, Lukas,Zielke, Katharina,Robiette, Rapha?l,Waser, Mario
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p. 11422 - 11428
(2016/08/03)
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- Efficient separation of a trifluoromethyl substituted organocatalyst: Just add water
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A practical, cost-saving tagging approach is developed which takes advantage of the hydrophobicity of trifluoromethyl groups, exemplified by the application and recovery of a CBS precatalyst using tuned aqueous-organic media with minimum 50% water content
- Dalicsek, Zoltan,Pollreisz, Ferenc,Soos, Tibor
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supporting information; experimental part
p. 4587 - 4589
(2010/01/06)
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- Asymmetric alternating copolymerization of cyclohexene oxide and CO2 with dimeric zinc complexes
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Dimeric zinc complex 2a [= Et2Zn2(1a)2] has been synthesized by the reaction of Et2Zn and (S)-diphenyl(pyrrolidin-2-yl)methanol (1a-H). X-ray crystallography revealed that the alkoxide ligand replaced one of the two ethyl groups of Et2Zn and formed a five-membered chelate ring through a Zn - N dative bond. Two zinc centers were bridged by oxygen atoms to form a Zn2O2 four-membered ring with a syn relationship between the two ethyl groups on the zinc centers. Dimeric zinc complex 2a was an active catalyst for asymmetric alternating copolymerization of cyclohexene oxide and CO2. An MALDI-TOF mass spectrum of the obtained copolymer showed that the copolymerization was initiated by the insertion of CO2 into Zn - alkoxide to give [(S)-diphenyl(pyrroridin-2-ly)methoxy] - [C(=O)O - (1,2-cyclohexylene) - O]n -H (copolymer I), including chiral ligand 1a as an initiating group. Complex 3a-OEt (= EtZn(1a)2ZnOEt), in which an ethoxy group replaced one of the two ethyl groups in 2a, also polymerized cyclohexene oxide and CO2 with higher catalytic activity and enantioselectivity than 2a and afforded EtO - [C(=O)O - (1,2- cyclohexylene) - O]n - H (= copolymer III), including an ethoxy group as an initiating group. Throughout the studies, dimeric zinc species are indicated to be the active species for the copolymerization. It is also depicted that the substituent on the aryl moiety in diaryl(pyrrolidin-2-yl)methanol 2b - e influenced the polymerization activity.
- Nakano, Koji,Nozaki, Kyoko,Hiyama, Tamejiro
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p. 5501 - 5510
(2007/10/03)
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- A Practical Enantioselective Synthesis of α,α-Diaryl-2-pyrrolidinemethanol. Preparation and Chemistry of the Corresponding Oxazaborolidines
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A practical two-step enantioselective synthesis of α,α-diaryl-2-pyrrolidinemethanols (1) from proline, based on the addition of aryl Grignard reagents to proline-N-carboxanhydride (3), is reported.An investigation into the chemistry of the corresponding B-alkyl- and B-aryloxazaborolidines (2) led to the development of a reliable procedure for their preparation.
- Mathre, David J.,Jones, Todd K.,Xavier, Lyndon C.,Blacklock, Thomas J.,Reamer, Robert A.,et al.
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p. 751 - 762
(2007/10/02)
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