Palladium(0)-Lithium Iodide Cocatalyzed Asymmetric Hydroalkylation of Conjugated Enynes with Pronucleophiles Leading to 1,3-Disubstituted Allenes.
Org Lett
; 21(17): 6811-6814, 2019 Sep 06.
Article
em En
| MEDLINE
| ID: mdl-31442059
ABSTRACT
Axially chiral 1,3-disubstituted allenes were synthesized via hydroalkylation of alkyl- or aryl-substituted conjugated enynes (readily prepared via a Sonogashira reaction) with pronucleophiles such as dimethyl malonate under the cocatalysis of DTBM-SEGPHOS-ligated palladium and lithium iodide. Although the palladium catalyst ligated with (S)-DTBM-SEGPHOS prefers the formation of (R)-1,3-disubstituted allenes, lithium iodide recovers and increases the intrinsic selectivity producing (S)-allenes by promoting the isomerization of the exo-alkylidene-π-allylpalladium intermediate prior to the nucleophilic substitution step.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Org Lett
Ano de publicação:
2019
Tipo de documento:
Article