| abstract |
In the above formula (1), R11 to R15 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, an acyl group, or a halogen atom provided that at least one of R11, R13, and R15 represents the alkoxy group or the aryloxy group; and R11 to R15 may form a ring structure therebetween. R5 and R6 each independently represent an alkyl group, an aryl group, or an aralkyl group. In addition, R21 to R24 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, an acyl group, or a halogen atom and may form a ring structure therebetween. The above groups except the acyl group may be substituted when necessary. |