SYNTHESIS OF NEW-TYPE DIACETAL TRIOXA-CAGE COMPOUNDS VIA AN INTRAMOLECULAR NUCLEOPHILIC-ADDITION OF THE HYDROXY GROUP TO THE CARBONYL OXIDEGROUP

The synthesis of diacetal trioxa-cage compounds with a new type of ske leton is reported. Ozonolysis of the diols 2a-f, 21, 24, and 33 in CH2 Cl2 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 m echanism via an intramolecular nucleophilic addition of the hydroxy gr oup of the diols to the carbonyl oxide group is proposed for the forma tion 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 trio xa-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 t he 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 perfor med by controlling the amount of ozone.