Facile synthesis and ring-opening cross metathesis of carbo- and heterocyclic bicyclo[3.2.1]oct-6-en-3-ones using gaseous olefinic reaction partners.

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Summary *

The title compounds were prepared by a facile [4+3]-cycloaddition strategy involving sonochemistry. The oxyallyl species required for the reaction with the corresponding diene was generated from a suitable perbromo ketone with activated zinc under sonification conditions. The resulting dibromo bicyclo compounds were reduced to the target products using a Cu/Zn couple. Ring-opening cross metathesis of the resulting bicyclic species was established as an efficient method for the diastereoselective preparation of >-3,5-disubstituted cycloketones. Especially gaseous olefins gave symmetrical and unsymmetrical products as versatile platforms for subsequent transformations. This is the first example of such a ringopening reaction of a non-strained ring system. Information provided by the agent in SIGEVA