Chemistry of furazans fused to five‐membered rings
Chemistry of furazans fused to five‐membered rings
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DOI：
10.1002/jhet.5570320201
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发表时间：
1995-03
影响因子：
2.4
通讯作者：
A. B. Sheremetev
中科院分区：
文献类型：
--
作者：
A. B. Sheremetev
1. 简介 90 年前，首次报道了稠合于五元碳环的呋喃（1,2,5-恶二唑）的制备方法[1]。五年后的 1908 年，首次描述了与五元杂环稠合的呋咱[2]。然而，制备此类化合物的困难是对这些有趣结构进行完整和彻底研究的主要障碍。 20 世纪 70 年代描述了新的合成路线，此后这些化合物的化学性质得到了长足的发展。 5/5 双环系统中的退火表明分子中存在应变能。各种结构特征会导致额外的扭曲。扭曲的芳香族恶二唑的不稳定不仅由键拉伸、角度扭曲、扭转效应和非键相互作用造成，而且还由共振稳定性降低造成。应变能表现为这些化合物难以形成或不稳定的倾向。文献中报道了许多五元环稠合呋喃。尽管本综述中的一些主题已被纳入有关呋喃衍生物的几篇早期评论 [3-11] 和有关呋喃/V-氧化物（呋喃酮）化学的广泛专着 [12]，但还没有完全专门针对五元环稠合呋喃的综合说明。
1. Introduction The first preparation of a furazan (1, 2, 5-oxadiazole) fused to a five membered carbocyclic ring was published 90 years ago [1]. A furazan fused to a five membered heterocycle was first described five years later in 1908 [2]. However, the difficulty in preparing such compounds was a major obstacle to a complete and thorough investigation of these interesting structures. New synthetic routes were described in the 1970's and the chemistry of these compounds has since developed considerably. Annelation in 5/5-bicyclic systems suggests the presence of strain energy in the molecules. Various structural features induce added distortions. Destabilization of the distorted aromatic oxadiazole results not only from bond stretching, angular distortion, torsional effects, and nonbonded interactions, but also from decreased resonance stabilization. Strain energy is manifested in a tendency to difficulty of formation or the instability of these compounds. There are a number of five membered ring condensed furazans reported throughout the literature. Although some topics in this review have been incorporated into several earlier reviews [3-11] on furazan derivatives and an extensive monograph [12] concerning the chemistry of furazan/V-oxides (furoxans), there has not been a comprehensive account devoted entirely to furazans condensed with five-membered rings.