Pd(O)-catalyzed cyclizations of (1-acetoxy-3-alkenyl)-2-cycloalkenes 3, 6 and 12 provide bicyclic systems in high diastereo- (5, 8) and enantio-meric (14) purity consistent with a predominant allylpalladium/alkene cis- insertion. Pd (o)-catalyzed, stereospecific (3 → 5,6 → 8) and enantiospecific (12 → 14) cyclizations are consistent with allylpalladium/alkene cis-insertions of 4, 7, 13 and represent a new approach to either cis - or trans-fused ring systems.