Patent ID: 8202983

Claim:
A compound having the structure of formula (I): wherein: B P is a protected or unprotected heterocyclic group having a 3 to 20 membered ring system; R 1 and R 2 are each independently selected from hydrogen, a protecting group, and a phosphoramidite group; R 3 is a hydrocarbyl that is not a silyl-containing hydrocarbyl or a substituted hydrocarbyl that is not a silyl-containing hydrocarbyl, and wherein R 3 is described by the structure: wherein R 3 ′, R 3 ″ and R 3 ′″ are each independently selected from H, a hydrocarbyl, a substituted hydrocarbyl, an aryl and a substituted aryl, wherein at least one of R 3 ′, R 3 ″ and R 3 ′″ is H; X and Y are each independently sulfur or oxygen, wherein at least one of X and Y is sulfur.