A cyclopropane fragmentation approach to heterocycle assembly: a convergent synthesis of oxepanes.
[reaction: see text] A cyclopropanol fragmentation approach to the synthesis of oxepanes has been developed. This convergent strategy condenses cyclopropyl diols with aldehydes to form an acetal, which is subsequently rearranged to furnish a keto-oxepane. The reaction has been developed as a one-pot procedure, utilizing sequential addition of Al(OTf)3 and TiCl4. Yields range from 50 to 70% for the sequence. A Zimmerman-Traxler transition state disposing substituents in equatorial positions is consistent with the observed formation of strictly cis products.
O'Neil
Kerry E
KE
Department of Chemistry, James Madison University, Harrisonburg, VA 22807, USA.
Kingree
Seth V
SV
Minbiole
Kevin P C
KP