Reactions over supported metal catalysts. IV. The stereochemistry and mechanism of hydrogenolysis of some propellanes

Abstract

Hydrogenolysis of the propellanes tricyclo[4,4,1,0^1,6]undecane and tricyclo[4,3,1,0^1,6]decane gives similar stereochemical ratios of products for reactions carried out either in acetic acid solution with a platinum oxide catalyst or over supported metal catalysts in the vapour phase. Almost equal amounts of cis- and trans-1- methylbicyclo[4,4,0]decanes are formed from the former, whereas cis-1- methylbicyclo[4,3,0]nonane predominates from reaction of the tricyclodecane. It is proposed that reaction of the highly strained propellanes over metal catalysts involves metal insertion reactions even for reactions over platinum in acetic acid solution. Deuterium incorporation studies are described which support this proposal.