The ubiquity of tertiary alkylamines in pharmaceutical and agrochemical agents, natural products and small-molecule biological probes^1,2 has stimulated efforts towards their streamlined synthesis^{3,4,5,6,7,8,9}. Arguably the most robust method for the synthesis of tertiary alkylamines is carbonyl reductive amination³, which comprises two elementary steps: the condensation of a secondary alkylamine with an aliphatic aldehyde to form an all-alkyl-iminium ion, which is subsequently reduced by a hydride reagent. Direct strategies have been sought for a ‘higher order’ variant of this reaction via the coupling of an alkyl fragment with an alkyl-iminium ion that is generated in situ^{10,11,12,13,14}. However, despite extensive efforts, the successful realization of a ‘carbonyl alkylative amination’ has not yet been achieved. Here we present a practical and general synthesis of tertiary alkylamines through the addition of alkyl radicals to all-alkyl-iminium ions. The process is facilitated by visible light and a silane reducing agent, which trigger a distinct radical initiation step to establish a chain process. This operationally straightforward, metal-free and modular transformation forms tertiary amines, without structural constraint, via the coupling of aldehydes and secondary amines with alkyl halides. The structural and functional diversity of these readily available precursors provides a versatile and flexible strategy for the streamlined synthesis of complex tertiary amines.

叔烷基胺在药物和农用化学品、天然产物和小分子生物探针^1,2中的普遍存在促进了对其简化合成^{3,4,5,6,7,8,9}的努力。可以说，合成叔烷基胺最可靠的方法是羰基还原胺化³，它包括两个基本步骤：仲烷基胺与脂肪醛缩合形成全烷基亚胺离子，随后被氢化物还原试剂。通过烷基片段与原位产生的烷基亚胺离子的偶联，已经为该反应的“更高阶”变体寻求直接策略^{10,11,12,13,14}. 然而，尽管付出了巨大的努力，“羰基烷基化胺化”的成功实现仍未实现。在这里，我们通过将烷基自由基添加到全烷基亚胺离子中，提出了一种实用且通用的叔烷基胺合成方法。该过程由可见光和硅烷还原剂促进，它们触发独特的自由基引发步骤以建立链式过程。这种操作简单、无金属和模块化的转化通过醛和仲胺与烷基卤化物的偶联形成叔胺，没有结构限制。这些容易获得的前体的结构和功能多样性为简化复杂叔胺的合成提供了一种通用且灵活的策略。