T 0219/98 (t-Butyl (R)-(-)-4-Cyano-3-hydroxybutyrate/TAKASAGO) 06-11-2001

1. The appeal is admissible.

Main request and auxiliary request I

2. Rule 57a EPC

Claim 2 of the main request and Claim 1 of the auxiliary request I differs from Claim 1 as granted in that the feature "having an optical purity of at least 99% ee" was added. This feature is designed to overcome a ground of opposition, namely absence of novelty. Therefore, that amendment can be admitted under Rule 57a EPC.

3. Article 123(2) and (3) EPC

The Board is satisfied that Claim 2 of the main request and Claim 1 of the auxiliary request I are not amended in such a way that they contain subject matter which extends beyond the application as filed. This amendment indeed finds support in the disclosure of the application as filed (cf. page 4, lines 17 to 20 and Example 1, page 9, line 24 to page 10, line 3).

Those claims are not amended as to extend the protection conferred, either.

4. Novelty - Article 54(3) and (4) EPC

4.1. Document (1) is comprised in the state of the art under Article 54(3) and (4) EPC in conjunction with Article 158(1) and (2) EPC. This was not contested by the Respondent.

4.2. Document (1) discloses (3R)-4-cyano-3-hydroxybutyric acid esters of formula (II): Formula

wherein R is alkyl of from one to ten carbon atoms, allyl or benzyl, the term "alkyl" meaning "a straight or branched hydrocarbon radical including, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, isobutyl, tertiary butyl ... and the like" (cf. page 5, lines 21 to 27). It is not disputed, in that respect, that the carbon in position -3 is in the chiral configuration (R).

A process for preparing compounds of formula (II) is outlined in the following scheme:

Formula

(cf. page 7),

wherein X is a leaving group such as halogen, R is as defined above and R1 is tetraalkylammonium, silver, copper (I), copper (II), an alkali metal or an alkaline earth metal. The reaction is carried out in a solvent at about 0 C to about the reflux temperature of the solvent (cf. page 8, lines 1 to 22).

The compound of formula (II) is said to yield the desired hexanoate of formula (I)

Formula

through a subsequent reaction (cf. scheme on page 7).

4.3. On that basis, the question to be decided is whether the individual t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate compound having an optical purity of at least 99% ee has been made available to the public by that disclosure. The Board holds, in accordance with the consistent jurisprudence of the Boards of Appeal, that the novelty of such an individual chemical compound falling under the scope of a general formula can only be denied if there is an unambiguous pointer to its individual configuration in the form of a technical teaching (cf. T 941/98, point 5.1; and T 296/87, OJ EPO 1990, 195, points 6.1 and 6.4 of the reasons). It is thus not sufficient that the compound in question belongs conceptually to a disclosed class of possible compounds, if there is no pointer to the individual member.

4.4. The Respondent, first, argued that the person skilled in the art would not have considered the (3R)-4-cyano-3-hydroxybutyric acid esters wherein R is "t-butyl" (cf. point 4.2 above) since its transformation in a compound of formula (I) failed (cf. point VII above). However, such an argument fails to recognize that the purpose of Article 54(1) EPC is to prevent the state of the art being patented. Article 54(2) EPC defines the state of the art as comprising everything made available to the public before the date of filing in any way. As set out in the decision G 1/92 (OJ EPO 1993, 277, in particular point 2.1 of the reasons), any element of subjectivity must be excluded in applying the concept of novelty as defined in Article 54(1) and (2) EPC. In particular, the Enlarged Board pointed out (in point 3 of the reasons) that the extrinsic characteristics, which are only revealed when the product is exposed to interaction with specifically chosen outside conditions, e.g., reactants or the like, in order to provide a particular effect or result point beyond the product per se. The Board, therefore, concludes that the argumentation of the Respondent based on a characteristic which is extrinsic to the compound, namely its further transformation, does not address the novelty issue to be decided.

4.5. The Respondent also argued that the (3R)-4-cyano-3-hydroxybutyric acid esters wherein R is "t-butyl" (cf. point 4.2 above) could only be regarded as an erroneous and therefore non novelty-destroying disclosure as established in the decision T 77/87 since its transformation in a compound of formula (I) failed (cf. point VII above). However, the Board observes that the situation which prevailed in the decision T 77/87 was quite different since, in that case, the Proprietor of the patent had shown that an error had occured in the published abstract of a document leading to a substantial inconsistency with the disclosure of the original document (the ratio of 30/50 for vinylidene chloride / vinyl chloride had been wrongly inverted). This error concerned an intrinsic property of the claimed composition. Therefore, in that case, the disclosure of the prior document was erroneous in respect of an aspect affecting the novelty of the claimed composition per se. In the present case, the Respondent did not adduce any convincing evidence for his contention; rather its sole argument amounted, in fact, to revert to what was previously presented but not accepted by the Board (cf. point 4.4 above) given that even a proven error related to an extrinsic property of a product is not decisive for establishing the disclosure of the said product. Again the Respondent's argument does not address the issue to be decided. The question whether the subsequent transformation of the compound of formula (II) in a compound of formula (I) can be achieved by the indicated route is not relevant for deciding whether or not the ester of formula (II) wherein R is "t-butyl" is disclosed in document (1).

4.6. The Board concludes, therefore, that the radical "t-butyl" stands for one possible meaning of R in the definition of the compound of formula (II) disclosed in document (1).

4.7. It remains to be decided whether the novelty of the claimed compound can be nonetheless acknowledged on the basis of a still undisclosed individualization. According to established jurisprudence of the Boards of Appeal a document disclosing polysubstituted chemical compounds does not qualify for a specific disclosure of an individual compound if the individual compound can only be derived from the generic disclosure by selecting one substituent from each of two or more lists of substituents (cf. decisions T 12/81, OJ EPO 1982, 296, point 13 of the reasons; T 7/86, OJ EPO 1988, 381, point 5.1 of the reasons). In applying this principle to the present case, the Board observes that once the skilled reader has turned his attention to the explicitly disclosed "t-butyl" radical as one of the meanings for the radical R, the t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate emerges clearly and unambiguously from the disclosure of document (1). Thus, the compound does not result from a "twofold/multifold" choice or selection required to confer novelty to the particular election of a compound within a generic formula. In that context, the decisions T 279/89 and T 666/89 which deal with the novelty issue of a claimed subject-matter in relation to the prior art where there is an overlap of numerical ranges or where there is a selection out of a broad numerical range, are not relevant. Furthermore, in the present case, the unambiguous pointer to the t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate is in the form of a technical teaching since document (1) describes a detailed method for obtaining the said compound (cf. in particular, page 8, line 1 to page 10, line 21).

In conclusion, the disclosure of document (1) points unambiguously to the individual compound t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate in Claim 1 of the patent in suit.

4.8. The Respondent also alleged that the distinctly different feature of the claimed t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate was the level of purity, i.e. at least 99% ee. However, the level of purity of a low molecular chemical compound, as a rule, cannot entail novelty since conventional methods for its purification are common general knowledge. Thus, a document disclosing such a chemical compound normally makes available this compound to the public within the meaning of Article 54 EPC in any level of purity (cf. T 990/96, OJ EPO 1998, 489, point 7 of the reasons and T 728/98, OJ EPO 2001, 319, point 6.4 of the reasons). No evidence was submitted from which the Board could conclude that in the present case an exceptional situation exists which would justify a different conclusion (cf. T 990/96, loc cit., point 8 of the reasons). The fact that the claimed product may exist in solid form which makes it purifiable by recrystallisation, whereas other esters such as the n-butyl ester only exist in liquid form, is not reflected in the features of the claims at issue (cf. Claim 2 of the main request or Claim 1 of the auxiliary request I) and, furthermore, is only an additional parameter for defining the said ester without giving rise to a different chemical product.

4.9. For the above reasons Claim 2 of the main request and Claim 1 of the auxiliary request I lack novelty over document (1), so that the patent in suit cannot be maintained in the form as submitted in those requests.

Auxiliary requests II, III and IV

5. Rule 57a EPC

Independent Claims 3 of the auxiliary requests II, III and IV differ from Claim 3 as granted in that the feature related to the level of optical purity, either 92% ee or 99% depending on the requests, has been added (cf. point V, b), c), d) above). Those respective features are designed to overcome a ground of opposition, namely absence of novelty. Therefore, that amendment can be admitted under Rule 57a EPC.

6. Article 123(2) EPC

6.1. All Claims 3 of the last three auxiliary requests have in common the technical feature according to which a t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate having an optical purity of at least 92% ee or at least 99% ee (with or without recrystallisation), depending on the claims, is obtained from a t-butyl (S)-(-)-4-halogeno-3-hydroxybutyrate of formula (II).

6.2. The sole concrete indication for the quantification of the level of enantiomeric purity can be found in Example 1. The Board observes nevertheless that in this example the t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate having an optical purity of, either 92% ee or 99% ee or more, is obtained from a t-butyl (S)-(-)-4-chloro-3-hydroxybutyrate having an optical purity of 92% ee (cf. page 9, line 5 of the application as filed). In that respect, the subject matter of Claim 3 of each request amounts to the combination of:

- the general disclosure referring merely to the reaction starting from any t-butyl (S)-(-)-4-halogeno-3-hydroxybutyrate, namely without any optical purity being mentioned at all (cf. page 5, lines 1 to 11 of the application as filed), with

- the particular optical purity value(s) for the t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate as indicated above (cf. point 6.1).

6.3. The generalisation of a feature from an example is considered to be allowable in accordance with decision T 201/83 (OJ EPO 1984, 481, point 12 of the reasons) provided that the person skilled in the art could have readily recognised this feature as not so closely associated with the other features of the example as to determine the effect of that embodiment of the invention as a whole in an unique manner and to a significant degree.

6.4. In the present situation, it cannot be derived from Example 1 that for any level of optical purity of t-butyl (S)-(-)-4-halogeno-3-hydroxybutyrate, a t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate having an optical purity of, either 92% ee or 99% ee or more, is necessarily obtained. By contrast, as shown by Example 1 (cf. page 4, lines 9 to 45 of the patent in suit), the optical purity of the t-butyl (R)-(-)-4-cyano-3-hydroxybutyrate is directly related to the optical purity of the starting t-butyl (S)-(-)-4-halogeno-3-hydroxybutyrate. It follows from the above that the subject matter of Claim 3 of each request amounts to an inadmissible generalization of the Example 1. For this reason, the amendments contravene Article 123(2) EPC.

6.5. Consequently, the auxiliary requests II, III and IV must fail.

7. As none of the requests submitted by the Respondent meets the requirements of the EPC, the patent in suit must be revoked. Therefore, there is no need to deal with the auxiliary request of the Appellant.