7-benzoyl-3a,4,5,7a-tetrahydro-1H-isoindole-1,3(2H)-diones 5, 8 and 9 in good yields. The 4-ethoxy group on the 2,4-pentadien-1-one was found to be effective to facilitate the cycloaddition with dienophiles. We also performed other [4+2] cycloadditions of 2,4-pentadien-1-ones with DMAD or naphthoquinone.
5-(苯基
硒烯基)-和5-(苯基亚磺酰基)-4-乙氧基-1-苯基-2,4-
戊二烯-1-酮(2)和(3)与N-甲基和N进行[4 + 2]环加成-苯基马来
酰亚胺和连续的异构化,以良好的产率得到7-苯甲酰基-3a,4,5,7a-四氢-
1H-异吲哚-1,3(2H)-二酮5、8和9。发现2,4-
戊二烯-1-酮上的4-乙氧基可有效促进亲二烯体的环加成。我们还用
DMAD或
萘醌进行了其他2,4-
戊二烯-1-酮的[4 + 2]环加成反应。