A mild and metal-free protocol for visible-light induced intramolecular radical cyclization of N-allyl(propargyl)-2-bromo-2,2-difluoro-N-arylacetamide has been developed. This strategy showed excellent regioselectivity and simple operation to synthesize 4-substituted 3,3-difluoro-γ-lactams with a broad substrate scope. Moreover, mechanistic studies revealed that this transformation proceeded through a cascade radical-type cyclization and hydrogen atom transfer process with PMDETA as a hydrogen-atom donor.

中文翻译：

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光催化分子内自由基环化涉及协同SET和HAT：3,3-二氟-γ-内酰胺的合成

已经开发出一种温和且无金属的方案，用于N-烯丙基（炔丙基）-2-溴-2,2-二氟-N-芳基乙酰胺的可见光诱导的分子内自由基环化。该策略显示出优异的区域选择性和简单的操作，可以合成具有广泛底物范围的4-取代的3,3-二氟-γ-内酰胺。此外，机理研究表明，这种转变是通过级联自由基型环化和氢原子转移过程进行的，其中PMDETA为氢原子供体。