. Author manuscript; available in PMC: 2011 Mar 8.

Published in final edited form as: Tetrahedron. 2006 Apr 17;62(16):3815–3822. doi: 10.1016/j.tet.2005.11.088

Table 2.

[2+2] Cycloadditions of ynamides with ketene

Entry	Ynamide	Cycloadduct	Yield (%)^a
1			79
2			80
3			65
4			67 (83)^b
5			86

Isolated yields of products purified by column chromatography.

Yield based on recovered starting material.