Use of the hexafluoro-2-butyl protecting group in the synthesis of DNA fragments via the phosphoramidite approach on solid supports

The hexafluoro-2-butyl (HFB) group is a new protecting group for internucleotidic bonds in the synthesis of oligodeoxyribonucleotides by the phosphoramidite approach. This group can be removed rapidly under the same condition as the 2-cyanoethyl group. Furthermore, we have found that the phosphitylating agent, hexafluoro-2-butyl-N.N-dialkylaminochlorophosphine, is easy to prepare in terms of its stability during purification by distillation, which does not require high vacuum.