Hybridon, Inc.

Nandkumar Bhongle

Jin-Yan Tang

New methods of synthesizing mono- and oligo- nucleotide H-phosphonates are disclosed. The methods comprise contacting a mononucleoside with phosphonic acid and benzoyl anyhydride to yield the corresponding mononucleoside H-phosphonate. Preferrably a catalytic amount of triphosgene is also used. A similar procedure can be used to couple a first mononucleoside to a second mononucleoside or to an oligonucleotide, the method comprising contacting, in the presence of benzoic anhydride and, preferrably, a catalytic amount of triphosgene, a mononucleotide or oligonucleotide having a free 5' hydroxyl with a mononucleoside having a 3' hydroxyl-bearing phosphorous moiety (preferably H-phosphonate).

Methods for H-phosphonate synthesis of mono- and oligonucleotides

New methods of synthesizing mono- and oligo-nucleoside H-phosphonates are disclosed. The methods comprise contacting a mononucleoside with phosphorous acid and triphosgene to yield the corresponding mononucleoside H-phosphonate. A similar procedure can be used to couple a first mononucleoside to a second mononucleoside or to an oligonucleotide, the method comprising contacting, in the presence of triphosgene, a mononucleoside or oligonucleotide having a free 5' hydroxyl with a mononucleoside having a 3' hydroxyl-bearing phosphorous moiety (preferably H-phosphonate).

Methods for H-phosphonate syntheis of oligonucleotides using triphosgene

New methods of loading solid supports for oligonucleotide synthesis are presented. The new methods comprise coupling a succinylated nucleoside to a solid support using diisopropylcarbodiimide (DIC) as an activator and N-hydroxybenzotriazole (HOBT) as an acid catalyst. DIC is substantially cheaper than the currently used activating agent, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (DEC). Furthermore, in the preferred embodiment, when it is used in combination with HOBT, coupling is more efficient, requiring less nucleoside to achieve the same loading densities as in the prior art. The loading process is faster than prior art methods and the overall cost savings of about 43% are realized.

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Shrewsbury, MA, United States of America

Nandkumar Bhongle