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Palladium(0)-Lithium Iodide Cocatalyzed Asymmetric Hydroalkylation of Conjugated Enynes With Pronucleophiles Leading to 1,3-Disubstituted Allenes

Hirokazu Tsukamoto, Tatsuya Konno, Kazuya Ito, Takayuki Doi

Org Lett. 2019 Sep 6;21(17):6811-6814.

PMID: 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.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP10377512 Lithium iodide Lithium iodide 10377-51-2 Price
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