Chemical transformation of tetraacetal tetraoxa-cages to aza-cages and amido-cages mediated by iodotrimethylsilane and the combination of chlorotrimethylsilane and sodium iodide in nitriles

Synthesis of novel acetal thia-cage compounds

The synthesis of novel acetal thia-cage compounds has been accomplished by the direct substitution for the oxygen atom by the sulfur atom in the reaction of the acetal groups of oxa-cages with Lawesson reagent (LR). Reaction of the tetraoxa-cage compound 2 with LR in dichloromethane at 25 degrees C sequentially gave the monothia-, dithia-, trithia-, and tetrathia-cage compounds 3, 6, 7, and 9. The reaction mechanism for the conversion from oxa-cages into thia-cages was proposed. The diacetal trioxa-cages 18-20 and 24-26 were also transformed into the thia-cages 21-23 and 27-29, respectively. Reaction of the trioxa-cages 34 and 35 with LR under the same reaction conditions gave the thia-cages 36 and 37 with the carbonyl group intact. Treatment of the pentaoxa[5]peristylane 40 with LR in chloroform under supersonic shaking at refluxing temperature gave the monothia[5]peristylane 41 and the dithia[5]peristylane 42. Attempts to synthesize the thia[5]peristylanes from the tetraoxa-cage 51 and the transformation from the parent (unsubstituted) pentaoxa[5]peristylane 46 to the thia-cages have been made. Reaction of the pentaoxa[5]-peristylane 40 with P(2)S(5) in refluxing toluene gave 41, 42, and a rearrangement product 47. The synthesis of new heterocyclic cage compounds 59 and 60, which contain oxygen, nitrogen, and sulfur atoms in the same molecule, was also accomplished.

Synthesis of Pentaoxa[5]peristylanes

The synthesis of alkyl-substituted pentaoxa[5]peristylanes has been accomplished by ozonolysis of 2,3-bis-endo-7-anti-triacylnorbornenes 6a-d and by direct chemical transformation of the tetraacetal tetraoxa cages 11 and 12. Various reaction conditions have been used to optimize the overall yield for the synthesis of methyl group substituted pentaoxa[5]peristylane 7d. Ozonolysis of 6d in CDCl(3) at -78 degrees C without reduction was performed to study the ozonolysis chemistry of the triacylnorbornenes 6a-d. The synthesis of the parent (unsubstituted) compound 25 of pentaoxa[5]peristylane has been accomplished by a three-step efficient sequence with a maximum 45% overall yield via ozonolysis of the dihemiacetal 24. The structure of pentaoxa[5]peristylanes was proven by X-ray analysis of the parent compound 25. The syntheses of the triacetal tetraoxa cage 26, a new type of oxa cage, and a new entry for the synthesis of the parent compound 33 of tetraacetal tetraoxa cages were also demonstrated.