Derivatives of two new [1] benzothieno medium-ring heterocyclic systems have been prepared by ring degradation using cyanogen bromide-induced solvolysis of tetracyclic precursors. Reaction of a hexahydro -[1] benzothieno [3,2-g] indolizine (4a) and a hexahydro-2H-[1] benzo-thieno [2,3-a] quinolizine (4b) with cyanogen bromide and magnesium oxide under solvolytic conditions yielded the hexahydro-1H-[1] benzothieno [3,2-d] azonines (5a) and (6a) and the octahydro -[1] benzothieno [3,2-d] azecines (5b) and (6b), respectively. Functional group interconversions of these medium-ring systems are described, including oxidations to the cyclic ketones (7) and (9). The 11b-phenyl derivative (13) of (4a) reacted under similar conditions to give both solvolysis (14) and (16) and elimination (15) medium-ring products, the ratios depending on the solvent. By contrast the analogous 9a-phenylthienoindolizine derivative (17) under these conditions gave only the medium-ring elimination product (18) in aqueous medium, and only the equivalent solvolysis product in methanol. Both the thieno and [1] benzothienoazonine elimination products (18) and (15) appear to be mixtures of E and Z isomers. The [1] benzothieno [3,2-g] indolizine bases (4a) and (13) are the first reported examples of this ring system.
利用溴化氰诱导四环前体溶解,通过环降解法制备了两个新的[1] 苯并噻吩中环杂环系统的衍生物。在溶解条件下,六氢-[1]苯并噻吩并[3,2-g]吲嗪(4a)和六氢-2H-[1]苯并噻吩并[2,3-a]喹嗪(4b)与溴化氰和氧化镁反应,得到六氢-1H-[1]苯并噻吩并[3、2-d]氮杂蒽 (5a) 和 (6a) 以及八氢-[1] 苯并噻吩并[3,2-d]氮杂蒽 (5b) 和 (6b)。介绍了这些中环系统的官能团相互转化,包括氧化生成环酮 (7) 和 (9)。(4a)的 11b 苯基衍生物 (13) 在类似条件下发生反应,生成溶解 (14) 和 (16) 以及消除 (15) 两种中环产物,其比例取决于溶剂。相比之下,在这些条件下,类似的 9a-苯基噻吩吲哚嗪衍生物 (17) 在水介质中只得到中环消除产物 (18),而在甲醇中只得到等量的溶解产物。噻吩和[1] 苯并噻吩嗪消除产物(18)和(15)似乎都是 E 和 Z 异构体的混合物。[1]苯并噻吩并[3,2-g]吲嗪碱(4a)和(13)是首次报道的这种环系统的实例。