Remote effects in the unsymmetrical ozonolysis of norbornene systems

MARÍA I. MANGIONE, SEBASTIÁN A. TESTERO, ROLANDO A. SPANEVELLO

Canela

Simposio; 11th Brazilian Meeting on Organis Synthesis; 2005

Sociedad Brasilera de Química

Ozonolysis is a widely applied reaction in organic synthesis. It is used to cleave multiple carbon-carbon or carbon-hetero-atom bonds. The pathway originally proposed by Criegee has been extensively confirmed. This reaction could be particularly interesting when an alkene is placed within a cyclic or polycyclic molecular structure. In this case, the cleavage could unveil a very useful functional group arrangement. A drawback that one could foresee is the generation of two similar functional groups, for this reasson the possibility of providing two different functional groups through the ozonolysis of a cycloalkene in a regioselective manner is highly desirable. Since the first unsymmetrical ozonolysis reported by Schreiber et al. in 1982 there were a few examples reported in the literature with moderate regiocontrol and yielding in all of them mixtures of compounds. This process could find a wide variety of applications in organic synthesis if it could afford only one regioisomer instead of a mixture of the two possible ones. Herein we wish to report the non symmetrical ozonolysis of a carbohydrate derived norbornene system that have shown a completely regioselective cleavage of the primary ozonide and the studies performed with other analogs in order to look for the possible remote factors that could account for the outcome of this unsymmetrical ozonolysis.