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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Halogenating Reagent-Triggered Annulation of Propargylic Amides With Carbon Dioxide Leading to
Wenchao Lu1, Boyu Shi1, Chao Chen1
1MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, P. R. China.
Abstract:
The conversion of CO2 into value-added chemicals represents a promising strategy for sustainable synthesis. Herein, we report a natural light-promoted cyclization of propargylic amides with CO2 using commonly used halogenating reagents as both the reaction promoter and halogen source to access 5-(halomethylene)oxazolidine-2,4-diones, which enables the one-pot construction of C─O, C─N, and C─X bonds. The protocol accommodates a broad range of substrates, and a variety of functional groups are well-tolerated under mild reaction conditions, providing access to functionalized oxazolidine-2,4-diones up to 92% yield as single E isomers. The mechanistic experiments reveal that the reaction may proceed along two pathways, which are the radical pathway (Path A) and the halonium pathway (Path B). The resulting 5-(halomethylene)oxazolidine-2,4-diones could be further transformed to complex molecules, highlighting the versatility.
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