Novel Photocleavable Protecting Groups for Primary Alcohols
The 9-phenylthioxanthyl moiety (S-pixyl) is an effective protecting group for primary alcohols. It can be cleaved from the parent alcohol by photochemical methods in addition to acid catalyzed cleavage. Previous studies included the investigation of S-pixyl analogues incorporating substitution on the 9-phenyl ring as well as the thioxanthyl backbone. These analogues required shorter irradiation times and gave excellent deprotection yields for thymidine when compared to the underivatized S-pixyl and analogous 9-phenylxanthyl (pixyl) moieties. However, analogues incorporating both types of substitution were not investigated.
Several S-pixyl analogues have been synthesized to determine the combined effects of substitution on the phenyl ring and the thioxanthyl backbone. The analogues were used to protect thymidine and investigated to determine deprotection yield and the time of irradiation needed for deprotection.