Aromatic molecules represent fundamental building blocks in prebiotic chemistry and are contemplated as vital precursors to DNA and RNA nitrogen bases. However, despite the identification of some 300 molecules in extraterrestrial environments, the pathways to pyridine (C₅H₅N), pyridinyl (C₅H₄N·) and (iso)quinoline (C₉H₇N)—the simplest representative mono- and bicyclic aromatic molecules carrying nitrogen—are elusive. Here we afford compelling evidence on the gas-phase formation of methylene amidogen (H₂CN·) and cyanomethyl (H₂CCN·) radicals via molecular beam studies and electronic structure calculations. The modelling of the chemistries of the Taurus molecular cloud (TMC-1) and Titan’s atmosphere contemplates a complex chain of reactions synthesizing pyridine, pyridinyl and (iso)quinoline from H₂CN· and H₂CCN· at levels of up to 75%. This study affords unique entry points to precursors of DNA and RNA nitrogen bases in hydrocarbon-rich extraterrestrial environments thus changing the way we think about the origin of prebiotic molecules in our Galaxy.

芳香族分子是生命起源前化学的基本组成部分，被认为是 DNA 和 RNA 氮碱基的重要前体。然而，尽管在地外环境中鉴定出了约 300 个分子，但吡啶 (C ₅ H ₅ N)、吡啶基 (C ₅ H ₄ N·) 和 (异)喹啉 (C ₉ H ₇ N)（最简单的代表）的途径携带氮的单环和双环芳香分子是难以捉摸的。在这里，我们通过分子束研究和电子结构计算提供了有关亚甲基氨基 (H ₂ CN·) 和氰甲基 (H ₂ CCN·)自由基气相形成的令人信服的证据。金牛座分子云 (TMC-1) 和土卫六大气的化学模拟考虑了从 H ₂ CN· 和 H ₂ CCN· 合成吡啶、吡啶基和（异）喹啉的复杂反应链，含量高达 75% 。这项研究为富含碳氢化合物的地外环境中 DNA 和 RNA 氮碱基的前体提供了独特的切入点，从而改变了我们对银河系中生命起源前分子起源的思考方式。