[2+2] Cycloaddition of ketenes with ynamides. A general method for the synthesis of 3-aminocyclobutenone derivatives

• Published in: Tetrahedron Vol. 62; no. 16; pp. 3815 - 3822
• Main Authors: Kohnen, Amanda L., Mak, Xiao Yin, Lam, Tin Yiu, Dunetz, Joshua R., Danheiser, Rick L.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 17-04-2006
• Subjects: [2+2] Cycloadditions; Cyclobutenones; Ketenes; Ynamides; [2+2] Cycloadditions; Cyclobutenones; Ketenes; Ynamides
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2005.11.088

Ynamides react with ketenes in [2+2] cycloadditions leading to a variety of substituted 3-aminocyclobut-2-en-1-ones. The ynamides employed in these reactions are readily available via the copper-promoted N-alkynylation of carbamates and sulfonamides with alkynyl bromides and iodides. The scope of the [2+2] cycloaddition with regard to both the ketene and ynamide component is described.
Graphical Abstract