Diels-Alder reaction of 2-(E-2-nitroethenyl)-1H-pyrrole (2a) with 1,4-benzoquinone gave the desired benzo[e]indole-6, 9(3H)-dione (4a) in 10% yield versus a 26% yield (lit. 86% [5]) of the known N-methyl compound (4b) from the N-(or 1)-methyl compound (2b). Protection of the nitrogen of 2a with a phenylsul-fonyl group (2c) gave a 9% yield of the corresponding N-(or 3)-phenylsulfonyl compound (4c).
2-(E -2-
硝基乙烯基)-1 H-
吡咯(2a)与1,4-苯醌的Diels-Alder反应得到所需的苯并[ e ]
吲哚-6,9(3 H)-二酮(4a)。从N-(或1)-甲基化合物(2b)得到的已知N-甲基化合物(4b)的产率为10%,而产率为26%(86%[5] )。用苯基磺酰基(2c)保护2a的氮得到9%的相应的N-(或3)-苯基磺酰基化合物(4c)。2b的反应用1,4-
萘醌的
苯甲酸酯的产率为6%(浓度为64%[5]),已知的3-
甲基萘[2,3 - e ]-
吲哚-6,9(3H)-二酮(6)。2-(E -2-
硝基乙烯基)
呋喃(8a)的反应产生少量所需的
萘并[2,1 - b ]
呋喃-6,9-二酮(9a),通过比较其NMR谱图可知的4b。2-(E -2-
硝基乙烯基)
噻吩(8b)的相应反应得到
萘并[2,1 - b ]
噻吩-6,9-二酮(9b)的产率为4%),先前制备过程以24%的收率[12],