Patent ID: 7541444

Claim:
A modified nucleotide molecule comprising a purine or pyrimidine base and a ribose or deoxyribose sugar moiety having a removable 3′-OH blocking group covalently attached thereto, such that the 3′ carbon atom has attached a group of the structure —O-Z wherein Z is any of —C(R IV ) 2 —O—R″, —C(R′) 2 —N(R″) 2 , —C(R′) 2 —N(H)R″, —C(R IV ) 2 —S—R″ and —C(R′) 2 —N 3 , wherein —C(R IV ) 2 —O—R″ is of the formula —CR 4 (R 5 )—O—CR 4 (R 5 )—OR 6 or of the formula —CR 4 (R 5 )—O—CR 4 (R 5 )—SR 6 ; and wherein —C(R IV ) 2 —S—R″ is of the formula —CR 4 (R 5 )—S—CR 4 (R 5 )—OR 6 or of the formula —CR 4 (R 5 )—S—CR 4 (R 5 )—SR 6 ; wherein each R″ is or is part of a removable protecting group; each R′ is independently a hydrogen atom, an alkyl, substituted alkyl, arylalkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, acyl, cyano, alkoxy, aryloxy, heteroaryloxy or amido group, or a detectable label attached through a linking group; or (R′) 2 represents an alkylidene group of formula ═C(R′″) 2 wherein each R′″ may be the same or different and is selected from the group comprising hydrogen and halogen atoms and alkyl groups; each R 4 and R 5 is independently a hydrogen atom or an alkyl group; R 6 is alkyl, cycloalkyl, alkenyl, cycloalkenyl or benzyl; and wherein said molecule may be reacted to yield an intermediate in which each R″ is exchanged for H, which intermediate dissociates under aqueous conditions to afford a molecule with a free 3′OH; with the proviso that where Z is —C(R IV ) 2 —S—R″, both R IV groups are not H.