A process for the preparation of a compound of formula (I) or a salt thereof
wherein R is an amino, nitro or —NHCOR
1
group, wherein R
1
is C
1
-C
6
alkyl or phenyl optionally substituted by a —O—(CH
2
)
n
-phenyl group, wherein n is an integer of 1 to 6; comprising reacting a compound of formula (II) or a salt thereof, both as the individual isomer and as an isomeric mixture,
wherein R is as defined above; with a dehydrating agent, if necessary in the presence of an organic solvent, and optionally in the presence of a basic agent; and, if desired, converting a compound of formula (I) to another compound of formula (I) or a salt thereof.
一种制备式(I)化合物或其盐的方法,其中R为
氨基,硝基或—NHCOR1基团,其中R1为C1-C6烷基或苯基,可选地被—O—(
CH2)n-苯基基团取代,其中n为1至6的整数; 包括将式(II)化合物或其盐与脱
水剂反应,如果必要,在有机溶剂存在下,可选地在碱性剂存在下,其中R如上所定义,包括其单一异构体和异构体混合物; 如果需要,将式(I)化合物转化为另一种式(I)化合物或其盐。