Department of Chemistry, University of Minnesota, 207 Pleasant Street, Southeast, Minneapolis, Minnesota 55455 United States.
Org Lett. 2021 May 7;23(9):3432-3436. doi: 10.1021/acs.orglett.1c00897. Epub 2021 Apr 19.
Arylhydrazines (ArNHNH) are ambident nucleophiles. We describe here their reactivity with benzynes generated in situ by thermal cyclization of several multiynes. Products arising from attack of both the alpha- and beta-nitrogen atoms are observed. These competitive modes of reaction were explored by DFT calculations. Substituent effects on the site-selectivity for several substituted phenylhydrazines were explored. Interestingly, the hydrazo products from beta-attack (ArNHNHAr') can be oxidized, sometimes in situ by oxygen alone, to give structurally complex, unsymmetrical azoarenes (ArN═NAr'). Toluenesulfonohydrazide and benzohydrazide analogues were each demonstrated to undergo similar transformations, including oxidation to the corresponding benzyne-trapped azo compounds.
芳腙（ArNHNH）是两可亲核试剂。我们在这里描述了它们与几种多炔热环化原位生成的苯炔的反应性。观察到了两种氮原子的α-和β-进攻产生的产物。这些竞争反应模式通过 DFT 计算进行了探讨。还探讨了几种取代苯腙的取代基效应对反应选择性的影响。有趣的是，β-进攻（ArNHNHAr'）生成的腙产物可以被氧化，有时仅通过氧气原位氧化，生成结构复杂、不对称的偶氮芳烃（ArN═NAr'）。甲苯磺酰腙和苯甲酰肼类似物都被证明可以经历类似的转化，包括氧化生成相应的苯炔捕获的偶氮化合物。
