Patent ID: 6610842
Filing Date: 2003-08-26
Classification: A61P,C07H

Abstract:
A method of preparing an oligomer having at least one moiety of formula: wherein:each X1 and X2 is, independently, O or S; Bx is a protected or unpprotected heterocyclic base moiety; and each R1 is, independently, H, a protected hydroxyl group, a sugar substituent group or a protected sugar substituent group; comprising the steps of: providing a compound of the formula: â€ƒwherein: T1 is a hydroxyl protecting group; and T2 is a covalent attachment to a solid support or a solid support bound nucleoside, nucleotide, oligonucleoside or oligonucleotide; removing the T1 group to form said compound having a 5â€²-hydroxyl group; and treating said compound having a 5â€²-hydroxyl group with a phosphoramidite composition to form an extended compound, said phosphoramidite composition comprising a phosphoramidite compound of the formula: â€ƒwherein: T3 is a protected hydroxyl group, a nucleoside, a nucleotide, an oligonucleoside or an oligonucleotide; R0 is a phosphorus protecting group; and each L1 and L2 is, independently, C1-4 alkyl; or L1 and L2 are joined together to form a 4 to 7-membered heterocyclic ring system including the nitrogen atom to which L1 and L2 are attached, wherein said ring system optionally includes at least one additional heteroatom selected from O, N and S; said phosphoramidite composition Her comprising at least about 2% by weight of impurities comprising at least one 3â€²-hydroxy nucleoside, a pill species different from said phosphoramidite compound where covalent attachment of groups to the PIII phosphorus of said PIII species is through oxygen or sulfur, or a PV species where covalent attachment of groups to the PV species is through oxygen, sulfur or nitrogen.