A compound of formula (I)
wherein
n is 0 to 4;
R is ethyl or vinyl;
R
1
is hydrogen or (C
1-6
)alkyl,
R
2
is hydrogen or
cycloalkyl including (C
3-6
)cycloalkyl, or
unsubstituted (C
1-6
)alkyl, or
(C
1-6
)alkyl substituted by one or more of
hydroxy; preferably one or two,
halogen,
(C
3-6
)cycloalkyl, or
R
1
is hydroxy and R
2
is formyl.
化合物的
化学式为(I),其中n为0到4;R为乙基或
乙烯基;R1为氢或(C1-6)烷基;R2为氢或环烷基,包括(C3-6)环烷基,或未取代的(C1-6)烷基,或被一个或多个羟基,最好是一个或两个,卤素,(C3-6)环烷基或(C1-6)烷基取代的(C1-6)烷基;当R1为羟基且R2为甲酰基时,优选该化合物。