Protecting Groups Transfer: Unusual Method of Removal of Tr and Tbdms Groups by Transetherification

The triphenylmethyl (Tr) group undergoes a transfer (transetherification or disproportionation) between the molecules of 5′-O-Tr-2′-deoxynucleosides in a process mediated by anhydrous sulfates of Cu⁺², Fe⁺², or Ni⁺² to yield mixtures of 3′,5′-bis-O-Tr and 3′-O-Tr products. If phenylmethanol is present in a reaction medium, detritylation results with concomitant formation of phenylmethyl triphenylmethyl ether. The behavior of t-butyldimethylsilyl (TBDMS) group in 5′-O-TBDMS-2′-deoxynucleosides is exactly the same. Such type of transetherifications was not observed before for the O-Tr and O-TBDMS groups.