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Synthesis of isoquinolines and pyridines by the palladium-catalyzed iminoannulation of internal alkynes.

Authors
  • Roesch, K R
  • Zhang, H
  • Larock, R C
Type
Published Article
Journal
The Journal of organic chemistry
Publication Date
Nov 30, 2001
Volume
66
Issue
24
Pages
8042–8051
Identifiers
PMID: 11722203
Source
Medline
License
Unknown

Abstract

A wide variety of substituted isoquinoline, tetrahydroisoquinoline, 5,6-dihydrobenz[f]isoquinoline, pyrindine, and pyridine heterocycles have been prepared in good to excellent yields via annulation of internal acetylenes with the tert-butylimines of o-iodobenzaldehydes and 3-halo-2-alkenals in the presence of a palladium catalyst. The best results are obtained by employing 5 mol % of Pd(OAc)(2), an excess of the alkyne, 1 equiv of Na(2)CO(3) as a base, and 10 mol % of PPh(3) in DMF as the solvent. This annulation methodology is particularly effective for aryl- or alkenyl-substituted alkynes. When electron-rich imines are employed, this chemistry can be extended to alkyl-substituted alkynes. Trimethylsilyl-substituted alkynes also undergo this annulation process to afford monosubstituted heterocyclic products absent the silyl group.

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