| 摘要 |
Compounds having the structural formula <CHEM> wherein R is C1-C6 alkyl; R<1> is hydrogen, C1-C6 alkyl, or R<a>-O-@- wherein R<a> is C1-C4 alkyl or R and R1 together are alkylene having 3 to 6 carbon atoms; R<2> is chlorine, bromine, iodine or C1-C4 aliphatic alkoxy; R<3> and R<4> independently are hydrogen or an aliphatic group; R<5> is hydrogen or C1-C6 alkyl; and R<6> is hydrogen or C1-C6 alkyl; and their salts. |
