Ceric ammonium nitrate on silica gel for efficient and selective removal of trityl and silyl groups

Silica gel-supported eerie ammonium nitrate (CAN-SiO2) was found effective for rapid and selective cleavage of trityl (Tr), monomethoxytrityl (MMTr), and dimethoxytrityl (DMTr) groups from protected nucleosides and nucleotide s under mild conditions. Efficiency of deprotections depended upon the stab ility of the resultant carbocationic species: DMTr+ > MMTr+ > Tr+, Use of a catalytic amount of this solid-supported reagent can also efficiently and selectively remove the tert-butyldimethylsilyl or the triisopropylsilyl gro up from a primary hydroxyl functionality in di- or trisilyl ethers of ribon ucleosides. A comparative study of deprotection reactions by utilization of CAN alone or CAN-SiO2 indicates a remarkable increase in the rate of the r eactions involving a solid support. The mechanism of electron-transfer proc esses is proposed for the use of CAN-SiO2 in the removal of these protectiv e groups from organic molecules.