Tandem 1,3-azaprotio cyclotransfer-cycloaddition reactions between ketoximes and divinyl ketone or its equivalents: Lewis acid mediated rate enhancement and control of cycloaddition regioselectivity

• Published in: Tetrahedron letters Vol. 38; no. 34; pp. 6099 - 6102
• Main Authors: Saba, Imaad S., Frederickson, Martyn, Grigg, Ronald, Dunn, Peter J., Levett, Philip C.
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 01.08.1997; Elsevier
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; CATALYZED NITRONE CYCLOADDITIONS; ALDOXIMES
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/S0040-4039(97)01377-4

The tandem 1,3-azaprotio cyclotransfer-cycloaddition reaction between a ketoxime and divinyl ketone or its equivalents [2-chloroethyl vinyl ketone and bis(2-chloroethyl) ketone] affords high yields of substituted 1-aza-7-oxabicyclo[3.2.1]octan-4-ones and 1-aza-8-oxabicylo[3.2.1]octan-4-ones. Addition of zinc bromide results both in rate enhancement and control of cycloaddition regioselectivity affording almost exclusively 1-aza-7-oxabicyclo[3.2.1]octan-4-ones. Tandem 1,3-azaprotio cyclotransfer-cycloaddition reactions between ketoximes and divinyl ketone or its equivalents [2-chloroethyl vinyl ketone and bis(2-chloroethyl) ketone] afford high yields of substituted 1-aza-7-oxabicyclo[3.2.1]octan-4-ones and 1-aza-8-oxabicylo[3.2.1]octan-4-ones. Addition of zinc bromide results both in rate enhancement and control of cycloaddition regioselectivity affording almost exclusively 1-aza-7-oxabicyclo[3.2.1]octan-4-ones.