Chloropropylsilyl spirolactones in the azetidine series also yielded two separable isomers (50ab, Scheme 4). In contrast to cationic azetidine dye 44, we found that displacement of the chloro group in the azetidine dye 50b with iodide was facile, yielding 53b (Scheme 3) and allowing entry to Si-Bridge spirolactone dyes with azetidine donors. We presume that azetidine ring-opening by iodide observed for 44 is facilitated by the partial positive charge on the azetidines in the cationic dye form, but not in the neutral spirolactone 50b.