A 3,4-cis isomer of 4-ethyl-1-(substituted phenyl)-3-(substituted phenyl)pyrrolidin-2-one, when reacted with a base, can be effectively convered into a 3,4-trans isomer thereof which has a high herbicidal activity useful as an effective ingredient for a herbicidal composition. Furthermore, 3,4-trans-4-ethyl-1-(substituted phenyl)-3-(substituted phenyl)pyrrolidin-2-one compounds represented by the formula (III)
(wherein R² is an isopropyl group, and X is a fluorine atom, chlorine atom or bromine atom substituted at the 3-position, or fluorine atoms substituted at the 3- and 4-positions or the 3- and 5-positions)
have an extremely excellent activity particularly as a herbicidally active ingredient of the herbicidal composition for rice paddy fields.
4-乙基-1-(取代
苯基)-3-(取代
苯基)
吡咯烷-2-
酮的 3,4-顺式异构体与碱反应后,可有效转化为 3,4-反式异构体,该异构体具有很高的除草活性,可作为除草组合物的有效成分。此外,3,4-反式-4-乙基-1-(取代
苯基)-3-(取代
苯基)
吡咯烷-2-
酮化合物由式(III)代表
(其中 R² 是
异丙基,X 是在 3 位被取代的
氟原子、
氯原子或
溴原子,或在 3 位和 4 位或 3 位和 5 位被取代的
氟原子)。
特别是作为稻田除草组合物的除草活性成分,具有极佳的活性。