Acid treatment of β-(3-acetoxyindol-2-yl)-α-cyanoacrylic acid derivatives (ethyl ester and nitrile) with aqueous or gaseous HCl afforded novel 3-substituted 2-oxo-2,5-dihydropyra-no[3,2-b]indoles. 2-Oxo-2,5-dihydropyrano[3,2-b]indole-3-carbonitrile was converted into ethyl 2-oxo-2,5-dihydropyrano[3,2-b]indole-3-carboximidate.
用
盐酸水溶液或气体对 β-(3-乙酰氧基
吲哚-2-基)-α-
氰基
丙烯酸衍
生物(
乙酯和腈)进行酸处理,可得到新型 3-取代 2-氧代-2,5-二氢
吡喃并[3,2-b]
吲哚。2-氧代-2,5-二氢
吡喃并[3,2-b]
吲哚-3-甲腈转化为 2-氧代-2,5-二氢
吡喃并[3,2-b]
吲哚-3-甲
亚胺乙酯。