Patent ID: 6992107

Claim:
A compound of formula I, R 2 2 N—CH 2 COCH 2 —CH 2 CO—OR 1 (I) wherein R 1 represents (a) an optionally substituted branched C 6-30 alkyl group, comprising a straight chain C 4-29 alkyl group, branched by substitution with one or more C 1-6 alkyl groups, wherein said site of substitution is at C2 or a higher C atom, or (b) a non-heteroaromatic aryl substituted alkyl group, wherein said aryl group is substituted, or (c) an alkoxy substituted alkyl group, wherein said alkoxy group is substituted by a methoxy group or an alkoxy group substituted with an alkoxy group, wherein in (a) and (b) said substituents are selected from hydroxy, alkoxy, acyloxy, alkoxycarbonyloxy, amino, aryl, nitro, oxo or fluoro groups, and said alkyl group is optionally interrupted or terminated by one or more —O—, NR 3 —, —S— or PR 3 — groups; R 2 , each of which may be the same or different, represents a hydrogen atom or a group R 1 , wherein R 1 represents (a) an optionally substituted branched C 5-30 alkyl group, comprising a straight chain C 4-29 alkyl group, branched by substitution with one or more C 1-6 alkyl groups, wherein said site of substitution is at C2 or a higher C atom, or (b) a non-heteroaromatic aryl substituted alkyl group, wherein said aryl group is substituted, or (c) an alkoxy substituted alkyl group, wherein said alkoxy group is substituted by a methoxy group or an alkoxy group substituted with an alkoxy group, wherein in (a) and (b) said substituents are selected from hydroxy, alkoxy, acyloxy, alkoxycarbonyloxy, amino, aryl, nitro, oxo or fluoro groups, and said alkyl group is optionally interrupted or terminated by one or more —O—, NR 3 —, —S— or PR 3 — groups; and R 3 represents a hydrogen or C 1-6 alkyl group).