Preparations of bicycliclactols from allyl and/or homoallyl propargyl acetal-cobalt complexes and its application to the formal synthesis of (±) loganine

Abstract 3-oxa-2-alkoxy bicyclo [3,3,0]-oct-5-en-7-ones and 3-oxa-2-alkoxy bicyclo [4,3,0]-non-5-en-7-ones were efficiently prepared from the corresponding bis(allyl or homoallyl)propargyl acetal-cobalt complexes in the presence of trimethylamine N-oxide. This methodology was successfully applied to the formal synthesis of (±) loganine.