Appeal No. 1999-1407
Application No. 08/295,744
for preparing certain types of oligonucleotides, … and that the authors were
unsuccessful in their attempts to develop yet another [third] technique….” We agree
with appellants. Bergstrom teach (page 873):
Modification at phosphorus can be achieved in conventional
phosphoramidite or H-phosphonate synthesis protocols by (1) utilizing
modified mononucleoside building blocks or (2) replacing the
oxidation cycle with a reaction that yields the modified phorphorus
linkage. The first approach works well for the construction of
methylphosphonate-linked oligonucleotides, while the second
approach is appropriate for phosphoramidate-linked
oligonucleotides.
…
One goal of our research is the development of new construction
techniques for oligonucleotide analogues substituted at phosphorus
by transition metal complexes.
It is Bergstrom’s “new construction technique for oligonucleotide analogues” that
failed.
The examiner applies Mitchell as another example that synthesis of new
nucleotide analogues is prone to failure. According to the examiner (Answer,
bridging sentence, pages 4-5) Mitchell “states ‘[t]he title complex (I) is less
convenient than Cl2CHCO2H (II) for routine automated DNA synthesis, but it is highly
effective in the synthesis of purine-rich oligomers that fail to give adequate yields
with II (abstract)’.” Initially, we note that the examiner’s citation is to a “CAPLUS”
abstract, and not to the Mitchell publication. The sentence cited by the examiner is
the last sentence of the Mitchell article, which states in full “BTMC is less convenient
than DCA for routine synthesis but it is a highly effective non-depurinating
detritylating agent in the synthesis of purine-rich oligomers that fail to give adequate
yields with DCA.” As appellants point out (Brief, page 6) Mitchell “simply states that
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