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.
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.
Conditions for metalation of a variety of cyclic vinylethers and reaction of the resulting carbanions with electrophiles are described. Effects of the vinylether structure on the relative rates of metalation are discussed. Applications of this methodology to the construction of various types of carbonyl compounds are presented.