Synthesis of new type diacetal trioxa-cage compounds via an intramolecular nucleophilic addition of the hydroxy group to the carbonyl oxide group

Abstract

The synthesis of diacetal trioxa-cage compounds with a new type of skeleton is reported. Ozonolysis of the diols 2a-f, 21, 24, and 33 in CH2Cl2 at -78 degrees C followed by reduction with Me2S gave the diacetal trioxa-cages 3a-f, 22, 25, and 34 in 70-80% yields, respectively. A mechanism via an intramolecular nucleophilic addition of the hydroxy group of the diols to the carbonyl oxide group is proposed for the formation of the diacetal trioxa-cages. The effect of the number of carbon atoms at the bridge of the diols on the formation of the diacetal trioxa-cage skeleton was examined. Ozonolysis of the diols 13 and 15 under the same reaction conditions gave compounds 16 and 18, respectively. No detectable amount of the trioxa-cages 17 and 19 was obtained. For the synthesis of the diacetal trioxa-cages 28a-c and 31, which possess an alkene bond intact, ozonolysis of the diols 27a-c and 30 was performed by controlling the amount of ozone.