Asymmetric Hydrogenation of 3-Substituted Pyridinium Salts.
Chemistry
; 22(28): 9528-32, 2016 Jul 04.
Article
em En
| MEDLINE
| ID: mdl-27140832
The use of an equivalent amount of an organic base leads to high enantiomeric excess in the asymmetric hydrogenation of N-benzylated 3-substituted pyridinium salts into the corresponding piperidines. Indeed, in the presence of Et3 N, a Rh-JosiPhos catalyst reduced a range of pyridinium salts with ee values up to 90 %. The role of the base was elucidated with a mechanistic study involving the isolation of the various reaction intermediates and isotopic labeling experiments. Additionally, this study provided some evidence for an enantiodetermining step involving a dihydropyridine intermediate.
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MEDLINE
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En
Ano de publicação:
2016
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Article