4 trophotometrically by monitoring the disappearance of the phenoxide ion absorption at 291 nm. Clean first-order behavior was observed in all cases. The kinetic results' are shown graphically in Figure 1. The most striking finding is a marked Ba2+-and Sr2+-induced increase in the cyclization rate, which strongly suggests that a template effect is involved in the process according to Scheme I, where the rate constant k'for the conversion of the ...