Appeal No. 2001-0694 Page 7
Application No. 08/908,807
that “[b]oth oxazolidine isomers are equally effective” in the synthesis of the taxol
derivatives, see id. at lines 61-64. It is unclear what diastereomers are produced,
but on column 80, the stereoisomer shown is the 4R,5S isomer.
Appellants contend that the diastereomers that are useful in the synthesis
disclosed by Kelly are the diastereomers that differ at the 2 position, in which the 4
and 5 positions have opposite stereochemistry, asserting that the diastereomers
produced by Kelly are the 2S,4S,5R, the 2S,4R,5S, the 2R,4S,5R and the 2R,4R,5S
diastereomers. See Appeal Brief, page 11. If, however, the 4S,5S was produced
by the Kelly process as part of the diastereomeric mixture, and was an inherent part
of that diastereomeric mixture, the Kelly reference would anticipate the acid of claim
17. See In re Best, 562 F.2d 1252, 1254-55, 195 USPQ 430, 433 (CCPA 1977)
(“[W]here the Patent Office has reason to believe that a functional limitation
asserted to be critical for establishing novelty in the claimed subject matter may, in
fact, be an inherent characteristic of the prior art, it possesses the authority to
require the applicant to prove that the subject matter shown to be in the prior art
does not possess the characteristic relied on.”)
Although Appellants have argued that the 4S,5S diastereomer would not
have been present in the diastereomeric mixture of Kelly, they also state in the
Appeal brief that “[a]t a minimum, Appellants’ inventive (4S, 5S) intermediates, if
made inadvertently, would have been an annoying side product needing to be
removed from the desired oxazolidine intermediates.” See Appeal Brief, page 12.
Although Appellants appear to back away from the position that the 4S,5S isomer
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