Bicyclo[3.2.1] type 1,2,4-trioxanes are readily synthesized from precursors that may form intramolecular hemiketals using UHP (H2O2-urea complex) as the source of the peroxy bond and p-TsOH or CSA as the catalyst. The ring closure through an intramolecular Michael addition occurred in a highly stereoselective way, giving only one diasteromer as shown by the NMR spectra. (c) 2006 Elsevier Ltd. All rights reserved.
the third molecule. The configurations of all stereogeniccenters in the bridged system can be effectively controlled by the chirality of the allyl alcohol as illustrated by the enantioselective synthesis of the fourth molecule. Finally, similar bicyclo[3.3.1]-type 1,2,4-trioxanes are shown very difficult to be synthesized because of the involvement of a conformer with two substituents at axial positions
Bicyclo[3.2.1] type 1,2,4-trioxanes are readily synthesized from precursors that may form intramolecular hemiketals using UHP (H2O2-urea complex) as the source of the peroxy bond and p-TsOH or CSA as the catalyst. The ring closure through an intramolecular Michael addition occurred in a highly stereoselective way, giving only one diasteromer as shown by the NMR spectra. (c) 2006 Elsevier Ltd. All rights reserved.