Kinetic and computational studies of the composition and structure of activated complexes in the asymmetric deprotonation of cyclohexene oxide by a norephedrine-derived chiral lithium amide†

2001 ◽  
pp. 1654-1661 ◽  
Author(s):  
Daniel Pettersen ◽  
Mohamed Amedjkouh ◽  
Sten O. Nilsson Lill ◽  
Kristian Dahlén ◽  
Per Ahlberg
Keyword(s):  
Computational Studies ◽  
Cyclohexene Oxide ◽  
Lithium Amide ◽  
Composition And Structure

Solvent-induced stereospecific isomerization of an allylic alcohol to a homoallylic alcohol catalyzed by a chiral lithium amide

1998 ◽  
Vol 76 (6) ◽  
pp. 795-799 ◽  
Author(s):  
Per I Arvidsson ◽  
Maria Hansson ◽  
Agha Zul-Qarnain Khan ◽  
Per Ahlberg
Keyword(s):  
Proton Transfer ◽  
Diethyl Ether ◽  
Allylic Alcohol ◽  
Cyclohexene Oxide ◽  
Deuterium Labeling ◽  
Lithium Amide

Deprotonation of cyclohexene oxide, 1, by lithium (S)-2-(1-pyrrolidinylmethyl)pyrrolidide, 2-Li, on changing the solvent from tetrahydrofuran (THF) to, for example, 2,5-dimethyltetrahydrofuran (DMTHF) or diethyl ether (DEE) has been shown to yield, besides the lithium alkoxide of 2-cyclohexene-1-ol, 3-Li, the lithium alkoxide of the homoallylic alcohol 3-cyclohexene-1-ol, 4-Li. It was shown that compound 4-Li is formed from 3-Li. No such rearrangement has been observed in THF. We have now shown that the solvent-induced isomerization of the lithium alkoxide of (S)-3-methyl-2-cyclohexene-1-ol, (S)-5-Li, catalyzed by 2-Li to the lithium alkoxide of (S)-3-methyl-3-cyclohexene-1-ol, (S)-6-Li, is 100% stereospecific. Furthermore, deuterium-labeling experiments suggest that the rearrangement of the proton is close to 100% intramolecular.Key words: 1,3-proton transfer, chiral lithium amide, intramolecular, solvent-induced isomerization, stereospecific.

High entropy alloy electrocatalysts: a critical assessment of fabrication and performance

2020 ◽  
Vol 8 (30) ◽  
pp. 14844-14862 ◽  
Author(s):  
Gracita M. Tomboc ◽  
Taehyun Kwon ◽  
Jinwhan Joo ◽  
Kwangyeol Lee
Keyword(s):  
Machine Learning ◽  
Present Status ◽  
Critical Assessment ◽  
Optimum Composition ◽  
High Entropy Alloy ◽  
Computational Studies ◽  
Combinatorial Screening ◽  
High Entropy ◽  
Composition And Structure ◽  
And Performance

Critical assessment of the present status of HEA NPs as catalysts, including an in-depth discussion of computational studies, combinatorial screening, or machine-learning studies to find the optimum composition and structure of HEA electrocatalysts.

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