Substitution in Spiropyrans

Bromination of 6-nitroBIPS to the 5 -bromo derivative could be carried out in excellent yield with bromine in chloroform (95%), A-bromosuccinimide in carbon tetrachloride (95%), cuprous bromide in acetonitrile (87%), or bromine in chloro- 

A method for preparing silica gel having BIPS groups bonded to it consists of metallating 6-bromoBIPS with butyllithium and causing the 6-lithioBIPS to react with silica. In a less efficient route to the same material, 4-methoxyphenyllithium (from the metallation of 4-bromoanisole) was coupled with silica gel. The resulting 

---