Conception and Evaluation of a Library of Cleavable Mass Tags for Digital Polymers Sequencing

A library of phosphoramidite monomers containing a main‐chain cleavable alkoxyamine and a side‐chain substituent of variable molar mass (i.e. mass tag) was prepared in this work. These monomers can be used in automated solid‐phase phosphoramidite chemistry and therefore incorporated periodically as spacers inside digitally‐encoded poly(phosphodiester) chains. Consequently, the formed polymers contain tagged cleavable sites that guide their fragmentation in mass spectrometry sequencing and enhance their digital readability. The spacers were all prepared via a seven steps synthetic procedure. They were afterwards tested for the synthesis and sequencing of model digital polymers. Uniform digitally‐encoded polymers were obtained as major species in all cases, even though some minor defects were sometimes detected. Furthermore, the polymers were decoded in pseudo‐MS 3 conditions, thus confirming the reliability and versatility of the spacers library