Transition-Metal-Free Carbofluorination of TBS-Protected Nitrogen-Containing Cyclic Enynols: Synthesis of Fluorinated Azabicycles

The synthesis of fluorinated azabicycles
from tert-butyldimethylsilyl-protected N-containing cyclic
enynols using inexpensive BF3·OEt2 is described.
In this reaction, BF3 reacts as both the Lewis acid and
the fluoride source for cyclization/fluorination of the TBS-protected
cyclic N-containing enynols. The method provides
an easy access to fluorinated azabicycles where a new C­(sp2)–F bond and a new bicyclic skeleton are generated at ambient
temperature within 1–13 min under metal-free reaction conditions.

本文报道了以廉价的三氟化硼乙醚络合物（BF₃·OEt₂）为试剂，由叔丁基二甲基硅基（TBS）保护的含氮环状烯炔醇合成氟化氮杂双环化合物的方法。在该反应中，三氟化硼同时充当路易斯酸与氟源，介导TBS保护的含氮环状烯炔醇的环化与氟化过程。该方法可在无金属、室温条件下，于1至13分钟内构建全新的C(sp²)-F键与双环骨架，从而便捷地获得氟化氮杂双环产物。