New applications of 1,5-hydrogen atom transfer reactions: Self-oxidizing protecting groups

Article abstract of DOI:10.1055/s-1992-34173

Three new alcohol protecting groups are introduced: o-bromobenzyl, o-bromo(methylenedioxy)benzyl, and o-bromotrityl. Removal of these protecting groups under reductive conditions with tributyltin hydride is coupled with an oxidation of the substrate to produce directly an aldehyde or ketone. This oxidation occurs by 1,5-hydrogen transfer, followed by β-fragmentation. For example, treatment of the o-bromobenzyl ether of 3-phenyl-1-propanol with tibutyltin hydride at 0.001 M (80°C) directly produces 3-phenyl-1-propanal. An application to the selective oxidation of primary alcohols in the presence of secondary alcohols is also introduced.