C-14 KIE (kinetic isotope effects) were measured for the C-1, C-2, C-4, and C-6 positions in the rearrangement of 2-(trimethylsiloxy)- (1a) and 2-(methoxycarbonyl)-3-oxa-1,5-hexadiene (1b). The data, along with earlier C-4 and C-6 deuterium KIE, were fitted to Bebovib modeling calculations. The calculations show that in the transition structure (TS) for 1a 70-80% bond breaking and 20% of bond making occurs, whereas in the TS of 1b both bond breaking and bond making amount to 30-40%. Results for 1a and 1b are compared with earlier results for the parent compound, allyl vinyl ether.