W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
Sci Adv. 2023 Mar 10;9(10):eadg1134. doi: 10.1126/sciadv.adg1134.
Oxirenes-highly strained 4π Hückel antiaromatic organics-have been recognized as key reactive intermediates in the Wolff rearrangement and in interstellar environments. Predicting short lifetimes and tendency toward ring opening, oxirenes are one of the most mysterious classes of organic transients, with the isolation of oxirene (-CHO) having remained elusive. Here, we report on the preparation of oxirene in low-temperature methanol-acetaldehyde matrices upon energetic processing through isomerization of ketene (HCCO) followed by resonant energy transfer of the internal energy of oxirene to the vibrational modes (hydroxyl stretching and bending, methyl deformation) of methanol. Oxirene was detected upon sublimation in the gas phase exploiting soft photoionization coupled with a reflectron time-of-flight mass spectrometry. These findings advance our fundamental understanding of the chemical bonding and stability of cyclic, strained molecules and afford a versatile strategy for the synthesis of highly ring-strained transients in extreme environments.
氧杂环戊二烯——高度应变的 4π Hückel 反芳香有机化合物——已被认为是 Wolff 重排和星际环境中的关键反应中间体。由于预测其寿命短且有开环倾向，氧杂环戊二烯是最神秘的有机瞬态类之一，其分离一直难以捉摸。在这里，我们报告了在低温甲醇-乙醛基质中通过酮烯（HCCO）异构化进行能量处理，随后通过将氧杂环戊二烯的内部能量共振转移到甲醇的振动模式（羟基伸缩和弯曲，甲基变形）来制备氧杂环戊二烯。通过升华在气相中检测到氧杂环戊二烯，利用软光电离并结合反射飞行时间质谱。这些发现增进了我们对环状、应变分子的化学成键和稳定性的基本理解，并为在极端环境中合成高度环应变瞬态提供了一种通用策略。
