Protective group, base-labile acid resistant

This group is more labile to hydrolysis than the TBDMS group and has been used to protect in alcohol where the TBDMS group was too resistant to cleavage. The DEIPS group is approximately 90 times more stable than the TMS group to acid hydrolysis and 600 times more stable than the TMS group to base-catalyzed solvolysis. 

Poly(hydroxystyrene) (PHOST) is often prepared by polymerization of 4-acetoxystyrene, followed by base-catalyzed hydrolysis (Fig. 9a). The ace-toxystyrene monomer s stability and polymerization kinetics allow production of PHOST of higher quality than is easily obtained via direct radical polymerization of HOST. The PHOST homopolymer formed thereby is then partially or fiilly derivatized with an acid-cleavable functionality to produce the final resist component. In some instances the resist polymer can be prepared in a single step by direct polymerization of the protected monomer(s) (23,45), entirely avoiding the intermediate PHOST. HOST-containing resist polymers have also been prepared by free-radical copolymerization of a latent HOST and a stable, acid-labile monomer, for example, the copolymerization of acetoxystyrene with tert-butyl acrylate, followed by selective removal of the acetoxy group (46) (Fig. 9b). 

---