The 9-phenylxanthen-9-yl protecting group

Abstract

9-Chloro-9-phenylxanthene (4b) reacts with the 5′-hydroxy groups of 2′-deoxyribonucleosides (2)(and their N-acyl derivatives) to give crystalline 9-phenylxanthen-9-yl (pixyl) derivatives (5) in satisfactory to good yields; the pixyl group may be removed by acidic hydrolysis under very mild conditions.