Novel Construction of Fused Pyridine Alkaloid Skeletons via Hetero Diels-Alder Reaction of Isotellurazoles

异tellurazole的Hetero Diels-Alder反应被认为是一种区域选择性合成取代吡啶的新方法，我们只是尝试将新方法扩展到短步合成融合吡啶生物碱骨架。经过大量的研究工作，我们刚刚尝试并成功地利用我们原始的异碲唑杂Diels-Alder反应和适当设计的缺电子乙基亲二酚作为重要的关键步骤，在短步骤合成了融合吡啶生物碱骨架。此外，我们还发现，所得到的吡啶环在合适的位置上有一个芳基和酯基，随后的Friedel-Crafts环闭合，并最终在相当温和的反应条件下合成了几个融合的吡啶生物碱骨架，即b-和d-羰基，1-和4-氮杂芴酮，1-氮杂蒽醌，1-氮杂蒽醌。

Hetero Diels-Alder reaction of isotellurazoles are recognized as a novel method for the regioselective synthesis of substituted pyridines, and we just attempted the expansion of the new methodology to the short-step synthesis of fused pyridine alkaloid skeletons. After an enormous efforts of our research work, we just attempted and succeeded in the short-step synthesis of fused pyridine alkaloid skeletons by using our original hetero Diels-Alder reaction of isotellurazoles and suitably designed electron-deficient acetylenic dienophiles as the important key step. Furthermore, we could find the subsequent Friedel-Crafts ring closure of the resulting pyridine ring bearing an aryl and ester groups on the suitable positions, and a convenient and short-step synthesis of a few fused pyridine alkaloid skeletons, i.e. b- and d-carbolines, 1- and 4-azafluorenones, 1-azaphenanthrenes, 1-azaanthraquinones, were finally achieved under a rather mild reaction conditions through our methodology.