| 摘要 |
The present invention provides a compound of formula(I) (wherein R<1> is an optionally substituted, saturated or unsaturated, straight-chained or branched hydrocarbyl group, preferably an alkenyl or poly(alkenyl) group; one of R<2> and R<3> represents a hydrogen atom and the remaining one of R<2> and R<3> represents a straight-chained or branched alkyl group; R<4> represents a hydrogen atom or a straight-chained or branched alkyl group, preferably a hydrogen atom; or, alternatively, R<1> and R<4> may be linked together to form an optionally substituted 5- or 6-membered ring) and metal salts and complexes, optical isomers and diastereoisomers thereof. |
