Wang Resin is perhaps the most widely used of all resins for SPOS. As a standard support it can be used for the solid phase immobilization of acids  and phenols  for SPOS. The ester linkage may be achieved, which has good stability to a variety of reaction conditions, but can be readily removed with the moderate acid treatment, generally with trifluoroacetic acid . For the immobilization of amines, Wang resin also can be readily converted into solid phase equivalents of standard urethane-based protecting groups by reaction with phosgene of activated carbonates, such as carbonyl diimidazole or bis(p-nitrophenyl)-carbonate .