Gold Catalysis: Alkylideneoxazolines and -oxazoles from Intramolecular Hydroamination of an Alkyne by a Trichloroacetimidate

Several propargylic trichloroacetimidates have been prepared and their reactions with gold catalysts studied. Only with the propargyl and the 1‐methylpropargyl substituent was a selective cyclization observed; with gold(III) chloride in acetonitrile only the product of a fast hydroamination to 4‐met...

Full description

Saved in:
Bibliographic Details
Published in:European Journal of Organic Chemistry 2006-11, Vol.2006 (21), p.4905-4909
Main Authors: Hashmi, A. Stephen K., Rudolph, Matthias, Schymura, Stefan, Visus, Jorge, Frey, Wolfgang
Format: Article
Language:English
Subjects:
Alkynes
Gold
Homogeneous catalysis
Hydroamination
Oxazoles
Oxazolines
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Several propargylic trichloroacetimidates have been prepared and their reactions with gold catalysts studied. Only with the propargyl and the 1‐methylpropargyl substituent was a selective cyclization observed; with gold(III) chloride in acetonitrile only the product of a fast hydroamination to 4‐methylene‐4,5‐dihydrooxazoles was obtained, in chloroform the slower subsequent aromatization could not be prevented which delivered the oxazoles after long reaction times. Up to 3333 turnovers could be reached. With gold(I) catalysts in chloroform or dichloromethane selective hydroamination to 4‐methylene‐4,5‐dihydrooxazoles without subsequent aromatization was exclusively observed. The gold(I) catalysts also allowed chemoselective cycloisomerization of N‐propargylcarboxamides to 5‐methylene‐4,5‐dihydrooxazoles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.200600572