Synthesis of Tetraacetal Tetraoxa-Cage Compounds with Alkyl Substituents at Different Sites of the Oxa-Cage Skeleton

Tetraacetal tetraoxa-cage compounds 3a, 3b, 4a, 4b, 7, 13,14 , and 15 were synthesized by a short sequence. They were obtained from ozonolysis of endo adducts la, lb, 2a, 2b , and 6 in dichloromethane at ?78 °C followed by reduction with dimethyl sulfide. Ozonolysis of 7-anti-trimethylsilyl-5,6-bis-endo-diacetylnorbornene 8 under the same reaction conditions did not give the tetraoxa-cage 9 . The methylsulfinyl oxa-cage 13 derived from l-methylthio-5,6-bis-endo-diacetylnorbornene 11 was converted to compounds 14 and 15.