The purpose of this paper is to report that pyrroles 1a-c also gave the 1:2 adducts 3a-c when refluxed with dimethyl acetylene dicarboxylate in ether (or ether with AlCl3) and rearrangement and degradation of 3a,7a-dihydroindole esters 3a-c as 1:2 molar [4+2] cycloadducts were investigated. The electrons in compound 3a are assumed to move as in its resonance structure A which should results in the formation of transition state B. Next, cleavage of the C-C bond between the carbonyl carbon atom and the 3a carbon atom and the 1,3-shift of the hydrogen atom from 7a position into 2 position will occur easily to form an aromatized stable indole compound 4a.
本文旨在报告当
吡咯 1a-c 与
乙醚中的
乙炔二
甲酸二甲酯(或
乙醚与
AlCl3)回流时,也会产生 1:2 加合物 3a-c,并研究了 3a,7a-二氢
吲哚酯 3a-c 作为 1:2 摩尔 [4+2] 环加合物的重排和降解。接下来,羰基碳原子和 3a 碳原子之间的 C-C 键发生裂解,氢原子从 7a 位向 2 位发生 1,3 移位,很容易形成芳香化的稳定
吲哚化合物 4a。