In the course of chemical research and discovery, it is often determined that it is not just a single compound that can perform the objectives of the invention but that a common activity exists throughout a genus of compounds. In cases in which there are only a few compounds in the family or genus, it is easy enough to specifically list each of them in a claim. In cases where the family or genus of compounds contains large amounts of compounds, the exercise of specifically listing each member of the genus quickly goes from merely tiring to nearly impossible. The most commonly employed solution to this problem is the use of Markush structures. As an example of a Markush format as applied to a set of organic molecules is shown in Figure below,in which nine naphthalene structures are shown as well as a Markush representation of those nine structures. As you can see even from this very small set, the Markush representation is much more economical in terms of both the time it would take to individually draw each structure as well as the space it would require to display aloof the individual structures.

That is, for an invention to be patentable, it must be novel. Since the Markush format is avery common way to claim chemical genera,15 it is critical that the practicing chemistappreciate the effect that disclosures in the prior art have upon the patentability of their claimed Markush structure. For this reason it is quite reasonable to ask, What


Figure : Naphthalene Markush.

sort of disclosure in the prior art would render my claimed genus not novel (i.e.,would anticipate my genus)? As we saw before, in order for something to be anticipated, the prior art must, in a single document, disclose each and every element of the chemist’sclaimed invention.
Let’s consider a patent application that contains a claim including the Markush group we have drawn in Figure above. The claim containing the naphthalene Markush is shown in Figure below. A prior art search reveals the following disclosures:Prior art disclosure 1 discloses and enables the preparation of the genus of compounds represented by the structural formula II in Figure below.
Prior art disclosure 2 discloses and enables the preparation of the genus of compounds represented by the structural formula III in Figure below.Prior art disclosure 3 discloses and enables the preparation of the compound represented by the structural formula IV in Figure below.

We claim:


FIGURE :Claim to naphthalene Markush.

Claim to naphthalene Markush.

Figure : Claimed genus (I) from Figure 7.2 and prior art genera and species.

Can you figure out if any of these disclosures will anticipate the claimed genus of naphthalenes of formula I?
First, let’s analyze the prior art disclosure 1 (compound formula II). The Markushgroup described by formula II is similar to the Markush group defined by our claimed structure I. For example, they both contain core-naphthalene rings with various optional combinations of substituents attached to the ring. Careful examination of the possible substituents defined by the prior art disclosure 1 indicate that it must always contain an n-propyl group at position 1 of the naphthalene ring. In contrast,the claimed genus of formula I cannot have an n-propyl group at the 1-position (the definition for R1 in formula I is hydrogen, methyl, or ethyl). If one were to draw aVenn diagram of these two described genera, one would have the situation as shown in Figure below. Where a disclosed genus in the prior art does not overlap with the


FIGURE :Venn diagram relationship between claimed genus (I) and prior art genus (II).

relationship between claimed genus (I) and prior art genus (II).

FIGURE :Prior art genus (III) with particularly selected variables.

The case of prior art disclosure 2 is more complex since there is an overlap between the prior art genus represented by formula III and the claimed genus of formula I.With the right picking and choosing of allowable substituents in formula III, we can come up with hypothetical examples that fall within the claim scope of genus I.16 As shown in Figure above, if we set Ra and Rb = hydrogen, and Rc and Rd to hydrogen or methyl, where Rc and Rd are positioned at the -1 and -2 position on the naphthalenering, this combination will produce a subset of four hypothetical compounds,where each of those four compounds fall within the scope of the claimed genus of formula I.
The four hypothetical compounds produced by specifically setting and placing Rc and Rd are just a few possibilities out of a much larger number of compounds that could have been constructed from the genus. A Venn diagram demonstrating the


Figure : Venn diagram overlay of prior art genus (III) with claimed genus (I).

relationship between the genus of formula III and the claimed formula I is shown in Figure above.

In order for a prior art genus to anticipate a later claimed genus, that prior art genus must place that the later claimed genus into the possession of the public,allowing one to at once envisage the later claimed genus. In the present case, prior art disclosure 2 provides a description of a genus that contains thousands of hypothetical compounds. Out of those thousands of compounds, only four hypothetical members fall within the scope of the claimed genus defined by formula I. To arrive at those four hypothetical examples falling within the claimed Markush I, one needs to pick and choose from various variables, carefully setting each one to a specified value and to a specific position. This is far from allowing one to at once envisage the later claimed Markush. While it may have not taken much effort for us to determine that some members of prior art reference 2 fall within the claimed Markush structure,this is with the benefit of hindsight (i.e., we have the claim to work backward from).
However, putting ourselves into the position of the inventor of formula I at the time of the invention, the question is whether the disclosure of formula III would have allowed him to at once envisage the claimed Markush I. The answer is no because the claimed genus of formula I is but one of an infinite set of overlapping hypotheticalMarkush structures available to the inventor at the time of her invention. Referring back to the first example in this describing the pigments and additives, we can appreciate that the situation with these two Markush groups is very similar to the prior art reference 5 of that example. In the prior art reference 5, one needed to mix and match pigments and additives to arrive at the later claimed composition; there was no composition actually disclosed that matched the later claimed composition. In the current example, the same thing is required since variables and positions must be determined and set in order to match the reference to the later claimed invention; the requisite level of specificity is not present. Anticipation requires that the thing being claimed must have already been identically disclosed. As such and absent more, the mere disclosure of a broadly overlapping genus will be insufficient to anticipate the later disclosed and claimed genus.

Finally, let’s consider prior art disclosure 3. For those of you who already figured out that prior art disclosure 3 would be an anticipatory disclosure, congratulations! It is an axiom of patent law that the prior art disclosure of a single species falling with in a later claimed genus will anticipate the claim to that genus. Notice that the priorart disclosure of 1-methylnaphthalene requires absolutely no picking and choosing of variables to arrive at its structure and that one can at once envisage its structure.It is also helpful to note that because 1-methylnaphthalene falls within the claimed generic structure, its structure matches exactly one of the possible structures falling
within the claimed Markush group of formula I (Figure above). Remember that we can think of the Markush claim as separately claiming each of the individual species falling within its range of possibilities, so we could rewrite the naphthalene genus claim 1 as shown in Figure above.

As we mentioned before, the claim is either anticipated or not. If one is claiming the equivalent of nine objects (compounds in this case) separately, the anticipation of one of those objects anticipates the claim. It should now be clear that the prior art compound formula IV is one of the nine choices (Figure above).
Finally, if we are not already convinced that the prior art species IV anticipates the later claimed genus I, we can apply the anticipation/infringement test. If we assume that the claimed genus I had issued into a patent and the prior art compound of formula IV was made after the claim genus was issued, we can agree that the making or selling of that compound in the United States would infringe the claim

compound selected

FIGURE :Claiming genus formula (I) as nine separate species.

FIGURE : Claiming genus formula (I) as nine separate species.

FIGURE :Anticipation of genus by prior art compound.

to the genus. It clearly falls within its claim scope. Accordingly, the making of that compound before the filing of the genus claim that covers the same compound will anticipate that compound. Therefore, the test is satisfied. The single species anticipates the genus.

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