Wydział Chemii

Shicheng Shi

Roger Lalancette

Roman Szostak

Michal Szostak

2016

Chemistry-A European Journal

22

11949-11953

10.1002/chem.201602717

Naukowa

Angielski

Artykuł

Samarium(II) iodide enables a wide range of highly chemoselective umpolung radical transformations proceeding by electron transfer to carbonyl groups; however, cyclizations of important nitrogen-containing precursors have proven limited due to their prohibitive redox potential. Herein, we report the first reductive cyclizations of unactivated cyclic imides onto N-tethered olefins using SmI2 /H2 O. This new umpolung protocol leads to the rapid synthesis of nitrogen-containing heterocycles that are of particular significance as precursors to pharmaceutical pharmacophores and numerous classes of alkaloids. The reaction conditions tolerate a wide range of functional groups. Excellent chemoselectivity is observed in the cyclization over amide and ester functional groups. Such unconventional reactivity has important implications for the design and optimization of new bond-forming reactions by umpolung radical processes. The reaction advances the SmI2 cyclization platform to the challenging unactivated N-tethered acyl-type radical precursors to access nitrogen-containing architectures.

C−C coupling, amide bonds, nitrogen heterocycles, samarium, umpolung

http://dx.doi.org/10.1002/chem.201602717

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