Perry Matthew J, Willis Anthony C, Bremner John B, Keller Paul A
School of Chemistry and Molecular Bioscience, Molecular Horizons, and Illawarra Health and Medical Research Institute, University of Wollongong Wollongong NSW 2522 Australia
Research School of Chemistry, Australian National University Canberra ACT 2601 Australia.
RSC Adv. 2023 Feb 6;13(7):4865-4873. doi: 10.1039/d3ra00481c. eCollection 2023 Jan 31.
In a continuation of the exploration of indigo cascade reactions, a series of -OMe, -Ph, -Br and -NO substituted indigos 1a-i were synthesised to probe electronic effects upon the outcome of allylation cascade reactions. When indigos 1a-i in the presence of base were reacted with allyl bromide, spiroindolinepyridoindolones 17-25 (36-75%) were obtained as the major products in each case, marking a shift in outcome relative to that previously reported for unsubstituted indigo. In electron-rich derivatives (-OMe, -Ph), -allylspiroindolinepyridoindolediones 26-29 (3-11%) were also isolated, which are most likely formed a Claisen rearrangement of the respective spiroindolinepyridoindolones 18-21. Additionally, the isolation of diallylbiindolone 16, oxazinobiindole 30 and ,-diallyl-3,3'-bis(allyloxy)biindole 31 each represented novel polyheterocyclic derivatives, providing intriguing new mechanistic insights, reaction pathways and in the case of 30 the first common heterocyclic skeletal outcome shared in both allylation and propargylation cascade reactions of indigo.
在靛蓝级联反应探索的延续中，合成了一系列 -OMe、-Ph、-Br 和 -NO 取代的靛蓝 1a-i，以探究电子效应对联烯化级联反应结果的影响。当在碱存在下靛蓝 1a-i 与烯丙基溴反应时，在每种情况下均以螺吲哚啉吡啶并吲哚酮 17 - 25（36 - 75%）作为主要产物得到，这标志着相对于先前报道的未取代靛蓝的结果发生了转变。在富电子衍生物（-OMe、-Ph）中，还分离出了 -烯丙基螺吲哚啉吡啶并吲哚二酮 26 - 29（3 - 11%），它们很可能是由各自的螺吲哚啉吡啶并吲哚酮 18 - 21 发生克莱森重排形成的。此外，二烯丙基联吲哚酮 16、恶嗪并双吲哚 30 和 γ,γ'-二烯丙基-3,3'-双（烯丙氧基）联吲哚 31 的分离各自代表了新型多杂环衍生物，提供了有趣的新机理见解、反应途径，并且就 30 而言，是靛蓝烯丙基化和炔丙基化级联反应中共享的首个常见杂环骨架产物。
