T 0296/87 (Enantiomers) of 30.8.1988

European Case Law Identifier: ECLI:EP:BA:1988:T029687.19880830
Date of decision: 30 August 1988
Case number: T 0296/87
Application number: 78101792.6
IPC class: C07C 59/58
Language of proceedings: DE
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Documentation of the appeal procedure can be found in the Register
Bibliographic information is available in: DE | EN | FR
Versions: OJ
Title of application: -
Applicant name: Hoechst
Opponent name: -
Board: 3.3.01
Headnote: A chemical substance is held to be new if it differs from a known substance in a reliable parameter. The configuration is such a parameter. If the prior art describes specific racemates in more detail by reference to their structural formulae, that alone does not disclose their specific configurations (here D- enantiomers); see points 6 and 7 of the Reasons (in conjunction with T 12/81 "Diastereomers", T 181/82 "Spiro compounds" and T 7/86 "Xanthines" in OJ EPO 1982, 296; 1984, 401; and 1988, 381 respectively).
Relevant legal provisions:
European Patent Convention 1973 Art 54
European Patent Convention 1973 Art 56
European Patent Convention 1973 Art 114
European Patent Convention 1973 Art 123
Keywords: New version of claims in opposition proceedings
Formulation attempt, not partial surrender
Novelty (yes) - enantiomers of known racemates
Inventive step (no)
Quantitatively surprising result of obvious tests (activity of enantiomer more than double that of racemate)
Objection of insufficient disclosure disregarded - not in due time e time


Cited decisions:
Citing decisions:
G 0001/16
T 0135/88
T 0572/88
T 0640/88
T 0021/89
T 0763/89
T 0012/90
T 0449/90
T 0731/90
T 0196/91
T 0294/91
T 0636/91
T 0686/91
T 0805/92
T 1048/92
T 0013/93
T 0412/93
T 0656/94
T 0024/95
T 0600/95
T 0727/96
T 0990/96
T 1046/97
T 0219/98
T 0368/98
T 0432/98
T 0564/98
T 0726/98
T 0940/98
T 0308/99
T 0400/99
T 0507/99
T 0717/99
T 0184/00
T 0260/00
T 0926/00
T 1072/00
T 0244/01
T 0321/01
T 0393/01
T 0866/01
T 0880/01
T 0773/02
T 0934/02
T 0857/04
T 0944/04
T 1394/05
T 1970/07
T 0423/09
T 1150/11
T 1677/11
T 1760/11
T 2397/11
T 1085/13
T 0143/14
T 0043/16
W 0030/04

Summary of Facts and Submissions

I. European patent No. 2 800 was granted on 2 December 1981 in respect of European patent application No. 78 101 792.6 filed on 20 December 1978 claiming German priority of 24 December 1977. The patent incorporated nine claims for the Contracting States BE, DE, FR, GB, NL and SE (referred to below as the "first group of Contracting States") and eleven claims for the Contracting State IT. Claim 1 for the first group of Contracting States was worded as follows:

"1. D-"-phenoxy-propionic acid derivatives of formula I where

R is a group of the formula


in which

R1 is hydrogen, halogen or CF3, R2 is hydrogen, (C1-C4)-alkyl, halogen or NO2, with the proviso that when R is a residue of formula II, III or VI, R1 is other than hydrogen, Z is a group of the formula


in which R3 is H, (C1-C12)-alkyl, optionally substituted with 1- 6 halogen atoms and/or OH, (C1-C6)-alkoxy, (C1-C4)-alkylthio, (C1-C6)-alkoxy-(C2-C6)-alkoxy, halo-(C1-C2)-alkoxy, methoxy- ethoxy-ethoxy, (C1-C4)-alkylamino, D-(C1-C4)-alkylamino, phenyl, oxiranyl or phenoxy, the latter optionally mono- or disubstituted with halogen and/or (C1-C4)-alkyl; (C5-C6)-cycloalkyl or halo- (C5-C6)-cycloalkyl; (C3-C6)-alkenyl, halo-(C3-C6)-alkenyl or (C5-C6)-cycloalkenyl, (C3-C4)-alkinyl, optionally mono- or disubstituted with (C1-C6)- alkyl, phenyl, halogen or (C1-C2)-alkoxy; phenyl, optionally mono- to trisubstituted with (C1-C4)-alkyl, (C1-C4)-alkoxy, halogen, NO2 or CF3; furfuryl, tetrahydrofurfuryl or a cation equivalent of an organic or inorganic base, R4 is (C1-C6)-alkyl optionally substituted with (C1-C4)-alkoxy, halogen or phenyl, the latter optionally mono- to trisubstituted with (C1-C4)-alkyl or halogen; (C3-C6)-alkenyl or phenyl optionally mono- to trisubstituted with (C1-C4)-alkyl and/or halogen, R5 and R6, being identical or different, are each H, (C1-C6)- alkyl, hydroxy-(C1-C6)-alkyl, (C5-C6)-cycloalkyl or phenyl, optionally mono- to trisubstituted with (C1-C4)-alkyl, (C1-C4)- alkoxy, halogen or CF3 (with the proviso that R5 and R6 are not both phenyl), or together form a methylene chain having 2, 4 or 5 members, wherein a CH2 group may be replaced by O, NH or N(CH3), R7 is H or CH3, R8 is H, CH3 or C2H5, R9 is H, CH3, C2H5 or phenyl, with the proviso that in compounds in which R is a group of formula II, R3 can be H or unsubstituted alkyl only if R1 or R2 is Cl in para-position." Claim 1 for the Contracting State IT differed from the above only in having at the end of the claim a less comprehensive "proviso" worded as follows: "...with the proviso that if R1 is trifluoromethyl, R2 is hydrogen and R is a group of formula II, then R3 is other than hydrogen". Each Claim 1 was followed by independent Claims 2 to 4 relating to a method for manufacturing compounds of formula I (in two variants, a and b), herbicidal compositions characterised by an active substance of formula I, and the use of compounds of formula I for combating undesirable plant growth. These were followed by Claims 5 to 9 and 5 to 11 relating to individual compounds within formula I.

II. The four respondents filed opposition to the patent on 10, 27 and 30 August and 2 September 1982 on grounds of lack of novelty and inventive step, one opponent (Ciba-Geigy) additionally claiming insufficient disclosure of variant b of the method described in Claim 2. Their oppositions were supported by various published documents of which ultimately only the following proved relevant: (1) DE-A-2 546 251, (2) EP-A-483, (3) DE-A-2 623 558 (4) Ann. Appl. Biol. 39 (1952), 295-307 and (9) DE-A-2 531 643 (essentially identical in content to (6) BE-A-831 469) and also by the following, which had not previously been published but predated the priority: (7) EP-A-1 473 and (8) EP-A-2 925.

III. During detailed discussion of the question of novelty and inventive step before the Opposition Division the patent proprietors (appellants) endeavoured to delimit their invention from the cited documents (cf. page 14, line 8, to page 15, line 18 of the contested decision) by amending certain meanings and some of the positionings of the substitutents R, R1 and R2 in Claim 1. The Opposition Division objected that the form of delimitation violated Article 123(2) EPC; and, when the patent proprietors defended that form of delimitation without amendment, finally revoked the patent solely on that ground by decision of 10 June 1987. No definitive assessment of substantive patentability was given, particularly with regard to novelty and inventive step (cf. page 11, last paragraph of the decision).

IV. On 7 August 1987 the proprietors of the revoked patent appealed against the Opposition Division's decision, paying the prescribed fee, and on 8 September 1987 submitted grounds together with four new sets of claims (main and subsidiary requests both for the first group of Contracting States and for Italy). Without going into the reasons for the contested decision the appellants abandoned the more narrowly worded claims submitted in opposition proceedings and tried to delimit the invention from the state of the art through disclaimers. They considered they were entitled to do this because they had not abandoned those parts which had been deleted, this having been done merely in an attempt to arrive at a formulation (page 4, paragraph 2 of the grounds for appeal). They did not mention the question of substantive patentability again in writing.

V. Of the four respondents, two (ICI and BASF) made no further comment on the matter in the appeal proceedings; one (Ciba- Geigy) did dispute the formal admissibility of the amended claims in written proceedings, but, like the two already mentioned, failed to appear at the oral proceedings to which they had been duly invited. In the written proceedings the fourth respondents (Dow) disputed the formal admissibility and substantive patentability of the claims set out in the requests valid at the time but, in summary fashion and without again submitting grounds. Before oral proceedings the Board pointed out by fax that the intention was to settle once and for all the question not only of the claims' formal admissibility but also of the substantive requirements for patentability.

VI. In oral proceedings on 30 August 1988, at which only Dow were represented as appellants and respondents (referred to below as "the respondents"), the submissions made were essentially as follows:

A. In a new main request the appellants submitted new claims differing from the granted version as follows: - In Claim 1 for the first group of Contracting States, the final passage worded "in which ... with the proviso that ..." is replaced by: "... but with the following restrictions: a) if R is the group of formula II, R3 can be H or unsubstituted alkyl only if R1 or R2 are at the same time C1 in para-position. b) if R is a residue of the formula R3 is other than hydrogen, (C1-C9)-alkyl, optionally substituted with one or more halogens or hydroxies; (C3-C4)-alkenyl, cyclohexyl, optionally substituted with one or more halogen atoms; phenyl, optionally substituted with one or more halogens or methyls; benzyl or a cation equivalent, c) formula II is other than in which n = 0 or 1, with a content of at least 80% D-form."; - in the relevant Claim 2, formula IX, Y is corrected to H; - the words "with a content of at least 80% D-form" are added to each of the sets of Claims 5 to 8; - in Claim 1 for IT, the final passage worded "in which ... with the proviso that ..." is replaced by: "but with the following restrictions: a) formula II is other than in which n = 0 or 1, b) ... (as for the first group of Contracting States) ..., with a content of at least 80% D-form."; - Claims 2 and 5 to 10 for IT are corrected in the same way as Claims 2 and 5 to 8 for the first group of Contracting States.

B. The appellants' subsidiary request comprises the following two claims, worded the same for all the designated Contracting States:

"1. Compound of the formula with a content of at least 80% D-form.

2. Compound of the formula with a content of at least 80% D-form."

C. In support of their main request the appellants asserted that it was standard EPO practice to consider enantiomers as novel compared with previously known racemates of equivalent structure. Numerous patents of this kind had been granted, even including some in respect of enantiomers of certain racemates specified in (9), of which the EPO had been aware at the time. With regard to inventive step, the appellants cited the test report submitted on 17 May 1985 from which it emerged that, for successful weed control with the D-enantiomer only a quarter of the required amount of the corresponding racemate was needed. Even had it been obvious to ascribe the entire activity of the racemate to the D-enantiomer, twice the activity of the racemate might have been expected at most, but in no way four times. They also pointed out that the herbicides in (4), in which the dextrorotatory were more active than the laevorotatory enantiomers, were compounds with different structure and functioning; nor could the d- (or +) and the D-form be automatically equated with each other. It would have been obvious to examine the D-enantiomers for such greatly improved activity only if such activity had already been known from compounds with a similar structure.

D. With regard to the subsidiary request the appellants pointed out that for one of the two compounds claimed - compound 20 - the test report dated 17 May 1985 showed an unusually sharp increase in the activity of the D-enantiomer compared with the racemate. Moreover the racemates corresponding to the two compounds claimed did not form part of the published state of the art but were merely described in one of the appellants' European applications with an earlier priority. They were thus relevant only to an assessment of novelty, not of inventive step.

E. (i) The respondents objected for one thing to the partial re- extension of Claim 1 in accordance with the main request submitted to the Opposition Division. The fact that the appellants had insisted on this despite the Opposition Division's objections showed that they had not merely been trying to arrive at a formulation but wished to dispense with more extensive protection. (ii) The respondents also asserted - for the first time - that certain substances belonging to the reactants of variant (b) and the necessary initial products of variant (a) of the process according to Claim 2 in the main request had not been available to experts in the field on the priority date and that therefore certain compounds in Claim 1 in which R = III had not been sufficiently disclosed within the meaning of decision T 206/83 "Herbicides", OJ EPO 1987, 5. (iii) Moreover, once Example 17 was eliminated there were no longer any examples to support compounds in which R = III - a further reason why these compounds could no longer be protected. (iv) The novelty of the claims in the current main request was no longer disputed. As regards inventive step, however, the respondents raised the objection that a quantitative improvement with D-enantiomers was neither adequately corroborated by the cited test report nor sufficient to prove inventive step. It was common knowledge among experts in the field that enantiomers often differed in their activity because they generally functioned via enzymes in the organisms treated, which for their part were optically active. In the case in question, document (4) not only disclosed that the dextrorotatory enantiomers of the compounds concerned were more active than the laevorotatory ones (page 295, paragraph 2) but also suggested that an antagonism was involved (page 295, paragraph 3), so that a factor > 2 for the activity of the d-enantiomer compared with the racemate was not surprising; moreover Fig. 4 on page 304 showed that the dextrorotatory (d-) enantiomers were the compound with the absolute D-configuration. However, greater activity in the d-form had been disclosed even for the compounds in (9) which were structurally more similar. It had therefore been obvious to propose the D-enantiomers in the contested patent (main request) to achieve a higher level of activity than that of the racemates. (v) The respondents did not comment on the current subsidiary request.

VII. The appellants requested that the contested decision be set aside and the patent maintained on the basis of the claims (main or subsidiary request) submitted in oral proceedings.

VIII. The respondents requested that the appeal be dismissed.

IX. The Chairman announced the Board's decision at the end of the oral proceedings.

Reasons for the Decision

1. The appeal complies with Articles 106 to 108 and Rule 64 EPC and is therefore admissible. Re the main request

2. Under the circumstances the version of the claims submitted on 17 August 1983 is to be regarded as an attempted formulation and not as renunciation of more extensive protection.

2.1 The new version of the claims filed on 17 August 1983 was intended to delimit the invention from the material filed in opposition proceedings (cf. page 2, lines 5 to 7, of the accompanying submission). There was no request from the Opposition Division for the claims to be restricted. On the contrary, the question of delimitation remained entirely open both during the proceedings and in the revocation decision; the items no longer mentioned in the amended claims cannot therefore have been surrendered.

2.2 Moreover a Board of Appeal had already decided (T 123/85 of 23 February 1988, OJ EPO 1989, 336) that the EPC made no provision for a patentee to surrender his patent in opposition proceedings, which meant that (even had there been an express declaration of surrender, which was not the case) he could not surrender his patent either wholly or in part. He could only request that it be amended and, in principle, could withdraw or amend such a request at any time provided no abuse of procedural law was involved (cf. points 3.1.1 and 3.1.2 of the decision cited). In the present case there is nothing to indicate any such abuse; in fact the complexity of the subject-matter makes it understandable that the appellants should have been most unsure as to what form of limitation the EPO would accept for establishing novelty.

2.3 The present claims, reworded in broader terms once again, must therefore be taken into account in each case.

3. Formal admissibility of the claims:

3.1 Article 123(3) EPC is not violated since the protection conferred is no broader than in the version granted. For the first group of Contracting States, two more disclaimers ("b" and "c") have been added to the single one (now "a") found in the version granted; in the version for IT, a broader disclaimer "a" has been introduced instead of the single disclaimer in the version granted and a second one "b" added.

3.2 Disclaimer "b" (worded the same for all the Contracting States) delimits the invention from document (8), which claims priority of 23 December 1977 and discloses inter alia D- enantiomers whose structure overlaps that specified in formula I of the contested patent. This overlap is due to the fact that R in formula I of the contested patent corresponds to formula II and -OR3 has certain meanings specified on page 3, lines 8 et seq. of (8) for the substituent R1 referred to in that document. A perusal of the priority document to (8), however, revealed that the meanings specified on page 3, lines 18 to 22, of (8) are not covered by this priority document, that (8) accordingly does not have an earlier filing or priority date than the contested patent and that the last-mentioned meanings of disclaimer "b" are rightly not excluded. The disclaimer nevertheless excludes in a permissible way the group of substances disclosed on pages 3 to 4 of the priority document.

3.3 Disclaimer "c" in Claim 1 for the first group of Contracting States and the identical disclaimer "a" in Claim 1 for IT (which also excludes what was already excluded by the single disclaimer in the Claim 1 granted for IT, therefore making that disclaimer superfluous) delimit the claim from prior publication (9). Owing to certain differences in the meanings of -OR3 in the contested patent and of R1 in Claim 1 of (9), this disclaimer does not exactly match the existing overlap: for instance, it also excludes the relevant compounds in which -OR3 = (C10-C12)-alkoxy although (9) anticipates only those with (C1- C9)-alkoxy. Nevertheless, it can be accepted because it eliminates all the overlaps, exceeds what is strictly necessary only in very minor details, and has the advantage over the latter of being considerably clearer.

3.4 The addition of the words "with a content of at least 80% D- form" at the end of Claim 1 and of Claims 5 to 8 for the first group of Contracting States, and of Claim 1 and Claims 5 to 10 for IT, is also justified in the light of page 6, lines 11 to 14, and page 10, lines 29 to 33, of the initial documents, corresponding to page 4, lines 21 to 23, and page 5, lines 56 to 58, of the contested patent.

3.5 The amendment made to formula IX in Claim 2 is a permissible correction under Rule 88 EPC since the "Y" should obviously have been an "H".

3.6 All in all the claims are unobjectionable under Article 123(2) EPC.

4. The objection of insufficient disclosure with regard to Decision T 206/83 (cf. point VI. E (ii) of the present decision) was raised for the first time in oral proceedings during the opposition appeal procedure, which means that it was not submitted in due time (Article 114(2) EPC). In fact it need not be considered in any case, there being other reasons why the appellants' main request cannot be granted (cf. point 8 below). It may nevertheless be noted that the respondents succeeded in convincing the Board neither that the substances in question are necessary initial products of variant (a) too, as defined in Claim 2 of the contested patent, nor that between the priority date of (2) - July 1977 - and that of the contested patent - December 1977 - there could have been no developments in general technical knowledge to make those substances accessible to the skilled person.

5. The objection that without Example 17 the description lacked sufficient support for compounds in which R = III (cf. point VI. E (iii) of the present decision) was not brought in due time. That example was dropped as long ago as 17 August 1983 when the new claims (in which R1 = CF3 and R2 = hydrogen or halogen) were submitted, as is also evident from disclaimer "b" of the version of the claims filed on 8 September 1987 as a subsidiary request. In any case, support for the claims in the description is a requirement of Article 84 EPC, infringement of which constitutes grounds neither for opposition nor, by extension, for appeal (cf. Article 100 in conjunction with Rule 66(1) EPC). The objection is therefore irrelevant.

6. The first requirement regarding novelty is to establish whether a known chemical formula evidently containing a (single) asymmetrical carbon atom destroys the novelty not only of the compound in the form of its racemate, but also of its enantiomers (d-and l-form or D- and L-form). This applies in particular to documents (1) to (3), which indisputably disclose structures overlapping those described in the contested patent, the only difference being that the latter claims D-enantiomers whereas the former makes no mention of them at all.

6.1 Here the Board is guided by the conclusions it reached in its "Spiro compounds" decision T 181/82 (OJ EPO 1984, 401) concerning the novelty of chemical entities within a group of substances of known formula. With regard to products of the reaction of specific spiro compounds with a (C1-C4)-alkyl bromide defined as a group, the Board drew a sharp distinction between the purely intellectual content of an item of information and the material disclosed in the sense of a specific teaching with regard to technical action. Only a technical teaching of this kind can be prejudicial to novelty. If any such teaching is to apply in the case of a chemical substance, an individualised description is needed. Thus, as the Board decided in that case, the purely intellectual content of the term (C1-C4)-alkyl comprises the eight groups methyl (C1), ethyl (C2), n- and iso- propyl (each C3), and n-, sec.-, iso- and tert.-butyl (each C4). Only the methyl group is disclosed in individualised form, however, since this is synonymous with the lower basic value C1- alkyl. In contrast, the special alkyl groups with two or three carbon atoms - included but not enumerated -are not disclosed in this way; nor are the four individual groups comprised in the upper basic value (C4), which discloses butyl groups only as a generic term.

6.2 The Board believes this principle applies in the present case to the extent that, judging by expert interpretations of the structural formulae and scientific designations to be found in the prior art, the latter describes only racemates. Given the asymmetrical carbon atom in the formula, the substances in question can indeed occur in many conceivable configurations (D- and L-enantiomers); that alone does not mean, however, that these configurations are disclosed in individualised form. The novelty of the D- and L-enantiomers is therefore not destroyed by the description of the racemates.

6.3 The situation is different if the state of the art includes enantiomers - howsoever designated (D, d, L, l or + or -) - which are specifically named and can be produced. 6.4 The Board's present view accords with its established case law on the novelty of chemical substances whereby the only technical teachings prejudicial to novelty are those which disclose a substance as the inevitable result of a prescribed method or in specific, i.e. individualised, form (cf. T 12/81, "Diastereomers", OJ EPO 1982, 296; T 181/82, "Spiro compounds", loc. cit.; T 7/86, "Xanthines", OJ EPO 1988, 381).

6.5 In taking this view the Board is aware that the two enantiomers, far from falling merely intellectually within the definition of the structure in question, actually exist unseparated in the racemate. Generally, the latter can also be separated by converting the enantiomers into a mixture of diastereomers, e.g. using optically active substances, then resolving the mixture and recovering the enantiomers from the resulting products. These considerations are immaterial to the question of novelty, however, and will be more usefully applied to the examination as to inventive step.

7. If these principles are adopted in the present case, the following emerges:

7.1 Documents (1) to (3) say nothing about enantiomers, nor is there any suggestion that they could occur during the manufacturing process described - say through the use of optically active starting materials. The Board concludes that this prior art is concerned only with racemates which do not affect the novelty of the D-forms claimed in the contested patent. This assessment must also apply to products according to the contested patent which - as finally claimed -have "a content of at least 80% D-form". For, as stated under point 6.5, any consideration of the possibility of racemate separation or enantiomer enrichment must be ruled out in the assessment of novelty.

7.2 The structures described in (4) are indisputably different from those in the contested patent, so that document is not prejudicial to novelty either.

7.3 Document (7) - not a prior publication - does in fact refer specifically (on page 4, second paragraph) to the dextro-and laevorotatory forms of structures overlapping those in the contested patent. No corresponding passage is to be found in the priority documents, however. Document (7) does not therefore enjoy priority in this respect and so does not destroy the novelty of the contested patent, quite apart from which the comments made on (1) to (3) also apply.

7.4 Document (8) - not a prior publication either - is likewise unprejudicial to novelty in view of disclaimer "b" (see point 3.2 of the present decision). That disclaimer properly excludes from the compounds defined by the contested patent's broad general formula I not only the individual compounds specifically named in the examples and elsewhere in (8), but also the entire group of substances disclosed in it (in the general formula) where that group's priority does indeed predate that of the contested patent.

7.5 The same applies to (9) in the light of disclaimer "c" for the first group of Contracting States and disclaimer "a" for IT. Accordingly, this document is also non-prejudicial to novelty.

8. With regard to inventive step (Article 56 EPC), the state of the art in (7) and (8) - not prior publications - may be disregarded, i.e. only (1) to (4) and (9) are to be considered.

8.1 The racemates corresponding to the claimed D-enantiomers may be regarded as the closest state of the art. For the claimed compounds in which R = II or III, these racemates are disclosed partly in each of (1), (2), (3) and (9); the racemates of those compounds in which R = IV, V or VI are not in fact disclosed in the said documents, but no separate communication as to inventive step is required in respect of the D-enantiomers in question since the appellants - as emerged from the oral proceedings - did not wish to make a special request to that effect.

8.2 Assuming the racemates specified in (1) to (3) and (9) to be the closest state of the art, the problem addressed by the contested patent may be seen as that of specifying compounds of which a considerably smaller quantity will be sufficient to combat unwanted plant growth. The solution proposed by the contested patent in Claim 1 of the main request comprises the compounds in formula I.

8.3 The test report filed on 17 May 1985 indicates that the problem is indeed solved.

8.4 Inventive step

8.4.1 Long before the contested patent's priority date, it was generally known to specialists that, in physiologically active substances (e.g. herbicides, fungicides, insecticides and growth regulators, but also pharmaceuticals and foodstuffs) with an asymmetrical carbon atom enabling them to occur in the form of a racemate or one of two enantiomers, one of the latter frequently has a quantitatively greater effect than the other or than the racemate. If - as here - the aim is therefore to develop agents with increased physiological activity from a physiologically active racemate the obvious first step - before any thought is given, say, to synthesising structurally modified products - is to produce the two enantiomers in isolation and test whether one or the other is more active than the racemate. Such tests are routine. Under established Board case law, an enhanced effect cannot be adduced as evidence of inventive step if it emerges from obvious tests. Since, in the present case, tests with the enantiomers were obvious in view of the task at hand, discovery of the claimed effect of the D-enantiomers compared with corresponding racemates does not involve an inventive step.

8.4.2 It should be noted that this conclusion can be generalised only to a limited extent. Thus the outcome might very well differ with compounds having more than one asymmetrical carbon atom, the number of possible isomers multiplying exponentially. Moreover if the basic racemate were indeed known but not in line with the general technical trend, the proposal that enantiomers be produced by splitting the racemate could be inventive. Other cases are also conceivable in which a different result would be achieved - e.g. the isolation of active enantiomers, or ones with a qualitatively different activity, from essentially inactive racemates or ones acting differently. In the present case, however, no such special aspects were put forward by the parties involved, nor are any evident to the Board.

8.4.3 Given the general nature of these considerations, the appellants' reference to the claimed compounds' different functioning compared with those described in (4) no more justifies a different assessment than do the respondents' arguments that the d-enantiomers are identical to the D- enantiomers in (4) and possibly also in (9). For if it was obvious to test whether one of the enantiomers of any common racemate having physiological activity is more active than the racemate itself, it no longer makes any difference which configuration proves more active or whether this result accords entirely with the closest state of the art.

8.4.4 The conclusion reached above is not affected even by the circumstance that the D-enantiomers in question exhibit not merely double but approximately four times the effectiveness of the relevant racemates - a fact adduced by the appellants and accepted by the Board. After all, if tests with enantiomers suggested themselves to a skilled person as an obvious way of arriving at a solution offering increased activity, the extent of that increase could not as a rule be taken as an indication that the tests - obvious as they were - involved an inventive step. For present purposes there is no need to try and establish whether a different view might be taken in extreme cases where the efficiency factor is so high that the process virtually involves obtaining an active enantiomer from an inactive racemate. With a factor of only 4, that would certainly appear inappropriate.

8.4.5 To sum up, the solution proposed in Claim 1 does not involve an inventive step.

9. Claim 2 concerns a method for the direct manufacture, in two varieties: a and b, of the D-enantiomers claimed in Claim 1. Although this method is not described in the prior art cited, and is therefore new, the appellants advanced no argument as to why it should be regarded as inventive and none are evident to the Board. Moreover a decision can only be given on a request as a whole, so for that reason alone Claim 2 must share the legal fate of Claim 1.

10. The same goes for Claims 3 and 4, which merely express the teaching in Claim 1 differently and are therefore not grantable either.

11. Claims 5 to 8 for the first group of Contracting States and 5 to 10 for IT relate to individual compounds under Claim 1, which - leaving aside the subsidiary request still to be dealt with - were not claimed to be patentable on their own. Nor are they legally valid for the purposes of the main request.

12. As far as the main request is concerned, the appeal is therefore unsuccessful. Re the subsidiary request

13. The two claims are essentially the same as the original Claims 9 and 10 and the granted Claims 7 and 8 for the first group of Contracting States, and Claims 9 and 10 for IT. Regarding the restriction to "at least 80% D-form", see point 3.4 of the present decision. There are thus no formal objections to the claims.

14. The arguments of insufficient disclosure and lack of any example of the compounds in which R = III (cf. points 4 and 5 of the present decision) are irrelevant from the outset because such compounds are not covered by the claims in the subsidiary request.

15. The subject-matter of both claims is new vis-à-vis all the prior art considered in the course of the proceedings, which discloses neither of the claimed compounds containing one benzothiazolyloxy or benzoxazolyloxy group.

16. Inventive step

16.1 Only the compounds specified in (1), (2), (3) and (9) in which R = II or III may be considered as the closest published prior art for the purposes of inventive step. In the Board's opinion the closest compound overall is compound 10 on page 9 of (1), which is identical to the two compounds claimed as regards both the basic structure indicated in Formula 1 and also the meaning and which also contains as an R substituent a heterocyclyloxy group in which only a chlorine atom is substituted (actually, a pyridyloxy group). Moreover the stereo configuration on the asymmetrical carbon atom is not indicated, which suggests that the racemate is involved (cf. the similar comments in points 6 and 7).

16.2 The test report dated 17 May 1985 did show convincingly that the compound in Claim 2 - identical to that in Example 20 in the contested patent - was superior to the corresponding racemate (page 3 of the table, compound 20); however, since this racemate does not, as far as can be seen, form part of the proven prior art, this effect is irrelevant. No claim was made with regard to an unexpected effect by comparison with what the Board considered the closest prior art (compound 10 in (1)) or with other substances in publications pre-dating the contested patent. The problem to be solved by the contested patent is therefore regarded as being merely to suggest further substances with good herbicidal activity. The information concerning compound 20 in the test report dated 17 May 1985 appears to indicate beyond reasonable doubt that this problem is indeed solved with the claimed substances.

16.3 A skilled person seeking further substances with good herbicidal activity will primarily consider compounds whose structure comes as close as possible to the substance from which he starts out - in this case compound 10 from (1). This is because in the limited area in which physiological - for instance, herbicidal - activity can be "expected" at all, it will be assumed that substances of comparable activity are most likely to be found among those having the closest structural similarity. Taking compound 10 from (1) as his point of departure, the skilled person looking for further suitable substances will first of all vary substituents R, R1 and X shown in the general formula in (1) and also their position in the molecule as a whole rather than fundamentally altering the structure and, for example, replacing the pyridyloxy group with a different heterocyclic group. Were he nevertheless to adopt the latter course, then even disregarding the choice of D-enantiomers he would be faced with a whole series of possibilities before actually selecting a chloro-substituted benzothiazolyloxy or benzoxazolyloxy group at a quite specific location. In view of the many mental steps required, the large number of possible variations and the considerable structural difference between the two substances claimed and compound 10 as described in (1), it cannot have been obvious to propose precisely these two as further compounds exhibiting good herbicidal activity - particularly since the cited prior art contains no suggestion of this, not to mention an example (cf. Decision T 20/83 "Benzothiopyran derivatives", OJ EPO 1983, 419, particularly points 5 to 7). The claimed solution therefore involves an inventive step.

17. The subsidiary request is therefore to be granted.


For these reasons, it is decided that:

1. The contested decision is set aside.

2. The appeal is dismissed in respect of the appellants' main request.

3. The case is remitted to the department of first instance with the instruction to maintain the European patent on the basis of the claims set out in the subsidiary request and a description which has yet to be adapted.

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