SYNTHESIS OF NOVEL TETRAACETAL OXA-CAGE COMPOUNDS FROM 2-METHYLTHIOFURANS

Several novel tetraacetal oxa-cage compounds 9a-9f were synthesized fr om the corresponding 2-methylthiofurans 1a-1f by a short sequence. The structures of these tetraoxa-cage compounds were deduced from their s pectral data and proven by X-ray analysis of 9a. Ozonolysis of the end o adducts 5a-5f in CH2Cl2 at -78 degrees C followed by reduction with dimethyl sulfide gave the tetraoxa-cages 9a-9f in 65-75% yields, respe ctively. Ozonolysis of the exo adduct 6a under the same reaction condi tions gave the tetracarbonyl compound 10. The phenylthio group substit uted tetraoxa-cage 13 and the tetraacetal oxa-cage 17, with one more c arbon atom on the apex position, were also synthesized in a similar se quence.