Patent ID: 8242258

Claim:
A ribonucleoside monomer having the structure: wherein B P is uracil or an amino-protected heterocyclic base, wherein said amino-protected heterocyclic base is selected to be unreactive during steps of ribonucleoside monomer synthesis and polynucleotide synthesis; and one of R 1 or R 2 is an aryl carbonate-type hydroxyl protecting group having the structure: wherein the dashed line indicates the site at which said aryl carbonate-type protecting group is bound to the 3′ or 5′ oxygen of said ribonucleoside monomer; Q 1 is an oxygen or a sulfur atom; and R 4 is an aryl group or a substituted aryl group; the other of R 1 or R 2 is selected from hydrogen, a protecting group, and a phosphoramidite group; and R 3 is an orthoester-type 2′ hydroxyl protecting group having the structure: wherein the dashed line indicates the site at which R 3 is bound to the 2′ oxygen of said ribonucleoside monomer; Q 2 and Q 3 are each independently either a sulfur or an oxygen atom; R 5 and R 6 are each independently selected from a hydrocarbyl, a substituted hydrocarbyl, an aryl, a substituted aryl, or R 5 and R 6 , together with Q 2 , Q 3 and the carbon to which Q 2 and Q 3 are attached are cyclically linked to form a heterocyclic group; and R 7 is selected from hydrogen, a hydrocarbyl, a substituted hydrocarbyl, an aryl, and a substituted aryl.