Ozonolysis of 2-endo-7-anti-diacylnorbornenes. A new entry for the synthesis of 2,4,6,13-tetraoxapentacyclo[5.5.1.0(3,11).0(5,9).0(8,12)]tridecanes

Abstract

A new route for the synthesis of the title compounds 4a, 4b, 10a, and 10b has been developed via ozonolysis of 2-endo-7-anti-diacylnorbornenes 3a, 3b, 9a, and 9b. The synthesis of the unsubstituted (parent) compound 4a of tetraacetal tetraoxa-cages has been accomplished for the first time by this new entry. Ozonolysis reactions of 3a, 3b, and 9a were also performed in CDCl3 for understanding the final ozonide structures and the ozonation chemistry. Ozonolysis of 3a, 3b, and 9a in CH2Cl2 at -78 degrees C followed by treatment with triethylamine provided an indirect support for the structures of the final ozonides 11a, 11b, and 14. (C) 1997, Elsevier Science Ltd.