Synthesis of Novel Tetraacetal Oxa‐Cage Compounds from 2‐Methylthiofurans

Several novel tetraacetal oxa‐cage compounds 9a‐9f were synthesized from the corresponding 2‐methylthiofurans la‐lf by a short sequence. The structures of these tetraoxa‐cage compounds were deduced from their spectral data and proven by X‐ray analysis of 9a . Ozonolysis of the endo adducts 5a‐5f in CH 2 C1 2 at −78 °C followed by reduction with dimethyl sulfide gave the tetraoxa‐cages 9a‐9f in 65‐75% yields, respectively. Ozonolysis of the exo adduct 6a under the same reaction conditions gave the tetracarbonyl compound 10 . The phenylthio group substituted tetraoxa‐cage 13 and the tetraacetal oxa‐cage 17, with one more carbon atom on the apex position, were also synthesized in a similar sequence.