The reaction of 2-haloethylidenecycloalkanes (ring size: 5, 6, 7, 8) with either methyl-2- butynoate or 2-butynyl methyl ether and Ni (CO) 4 in methanol affords mainly two type of bicyclic compounds: 5-cycloalkenylidenecyclopent-2-enones and 5-(1-cycloalkenyl) cyclopent-2-enones. The origin for the diversion of the process towards elimination instead of alkoxycarbonylation is interpreted as the result of the mutual conformation of the two ...
