| http://www.w3.org/ns/prov#value | - [20] the compound according to [19]; provided that the case wherein R3 and R4 taken together form tetramethylene and R1 is a group represented by the formula: ???Y1???Y2???Y3???Ra wherein Y1 and Y3 are single bond; Y2 is ???O???; Ra is phenyl is excluded;
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