腈亚胺的重排：苯甲胺亚胺的环扩展为环庚酸酯和环闭合为3-Phenyl-3 <i>H</i> -diazirines,The Journal of Organic Chemistry

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腈亚胺的重排：苯甲胺亚胺的环扩展为环庚酸酯和环闭合为3-Phenyl-3 H -diazirines
The Journal of Organic Chemistry ( IF 3.3 ) Pub Date : 2019-06-07 00:00:00 , DOI: 10.1021/acs.joc.9b01183
Didier Bégué ₁ , Alain Dargelos ₁ , Curt Wentrup ₂

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腈亚胺是1，3-偶极环加成反应中的重要中间体，并且还已知它们在热和光化学反应条件下均会通过1 H-二嗪和亚氨基亚硝基苯胺进行高效，单分子重排成碳二亚胺。我们现在报告一个竞争性重排，由CASPT2（14,12）和B3LYP计算揭示，其中C-苯基腈亚胺8经历扩环反应，形成类似于苯基碳烯-环庚二烯的1-二氮烯基-1,2,4,6-环庚二烯12重排。C的间位上的氨基，羟基和硫醇基-苯腈亚胺降低了该重排的活化能，因此它与环化成1 H-二嗪类有潜在竞争性，因此重排成碳二亚胺。如此形成的二氮烯基环庚二烯12可以在适度的激活屏障上进一步发展为环庚二烯30和2-二氮烯基-苯基碳烯16，后者的卡宾很容易环化为2 H-和3 H-吲唑，从中可以生成6-亚甲基环己二烯，苯基碳烯，富烯基，及其异构体是潜在可获得的。此外，苄腈亚胺的另一个新重排形成了3-phenyl-3 H-重氮基，它是苯基重氮甲烷的前体，因此是苯基碳烯的前体。该反应与环扩展竞争。此处预测的新的重排应在实验上可观察到，例如在基质光解或快速真空热解条件下。

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Rearrangements of Nitrile Imines: Ring Expansion of Benzonitrile Imines to Cycloheptatetraenes and Ring Closure to 3-Phenyl-3H-diazirines

Nitrile imines are important intermediates in 1,3-dipolar cycloaddition reactions, and they are also known to undergo efficient, unimolecular rearrangements to carbodiimides via 1H-diazirines and imidoylnitrenes under both thermal and photochemical reaction conditions. We now report a competing rearrangement, revealed by CASPT2(14,12) and B3LYP calculations, in which C-phenylnitrile imines 8 undergo ring expansion to 1-diazenyl-1,2,4,6-cycloheptatetraenes 12 akin to the phenylcarbene—cycloheptatetraene rearrangement. Amino-, hydroxy-, and thiol-groups in the meta positions of C-phenylnitrile imine lower the activation energies for this rearrangement so that it becomes potentially competitive with the cyclization to 1H-diazirines and hence rearrange to carbodiimides. The diazenylcycloheptatetraenes 12 thus formed can evolve further to cycloheptatetraene 30 and 2-diazenyl-phenylcarbene 16 over modest activation barriers, and the latter carbenes cyclize very easily to 2H- and 3H-indazoles, from which 6-methylenecyclohexadienylidene, phenylcarbene, fulvenallene, and their isomers are potentially obtainable. Moreover, another new rearrangement of benzonitrile imine forms 3-phenyl-3H-diazirine, which is a precursor of phenyldiazomethane and hence phenylcarbene. This reaction is competitive with the ring expansion. The new rearrangements predicted here should be experimentally observable, for example, under matrix photolysis or flash vacuum pyrolysis conditions.

更新日期：2019-06-07

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