The alkene group may be unsubstituted, i.e. all of the carbon atoms are bound with hydrogen, or substituted, i.e. one or more of thehydrogen atoms are replaced with a lower alkyl and/or aryl group particularly one having six carbon atoms in the ring such as phenyl or benzyl.The catalyst may be represented as: ##STR1## where M is a transition metal such as rhodium, iridium or ruthenium, R is ##STR2