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DOI: 10.1055/s-0030-1258720
Preparation of Indolizines via Palladium-Catalyzed Cycloisomerization
Contributor(s):Paul Knochel, Thomas KunzKangwon National University, Chuncheon, Republic of Korea; Nanyang Technological University, Singapore
An Efficient Preparation of Indolizines through a Tandem Palladium-Catalyzed Cross-Coupling Reaction and Cycloisomerization
Chem. Commun. 2010, 46: 6341-6343
Publication History
Publication Date:
21 October 2010 (online)
Key words
cross-coupling - organoindium reagents - palladium
Significance
This work discloses a one-pot preparation of indolizines via a tandem cross-coupling and cycloisomerization. The organoindium reagent is generated in situ from propargyl bromides. The authors propose that after the cross-coupling step, the cycloisomerization of the intermediate allenylpyridine occurs by the attack of the nitrogen atom with a 5-endo mode.
Comment
A method for the direct formation of indolizines has been developed. However, relatively high catalyst loads are necessary for good yields. The ethoxycarbonyl group on the alkyne moiety is essential for the cyclization and sodium iodide is required for the in situ formation of the alkynylindium reagent.