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Ground-state dioxygen undergoes metal-free [3 + 2]-annulations with allenes and nitrosoarenes under ambient conditions.

ABSTRACT: The cycloadditions of molecular dioxygen with neutral ?-bond motifs rely heavily on singlet-state ¹O₂, whereas ground state ³O₂ is chemically inactive. Here we report novel [3 + 2]-annulations among ground-state ³O₂ (1 bar), allenes, and nitrosoarenes at low temperatures, efficiently yielding dioxygen-containing oxacycles. With less hindered 1-arylallene derivatives, these dioxygen species undergo skeletal rearrangement to 3-hydroxy-1-ketonyl-2-imine oxides. These cycloadditions represent valuable one-pot O,N,O-trifunctionalizations of allenes. Our EPR experiments confirm the presence of 1,4-diradical intermediates from an allene/nitrosoarene mixture, which manifest the hidden diradical properties of nitrosoarenes.

SUBMITTER: Liu J

PROVIDER: S-EPMC5613744 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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Ground-state dioxygen undergoes metal-free [3 + 2]-annulations with allenes and nitrosoarenes under ambient conditions.

Liu Jinxian J Skaria Manisha M Sharma Pankaj P Chiang Yun-Wei YW Liu Rai-Shung RS

Chemical science 20170524 8

The cycloadditions of molecular dioxygen with neutral π-bond motifs rely heavily on singlet-state 1O2, whereas ground state 3O2 is chemically inactive. Here we report novel [3 + 2]-annulations among ground-state 3O2 (1 bar), allenes, and nitrosoarenes at low temperatures, efficiently yielding dioxygen-containing oxacycles. With less hindered 1-arylallene derivatives, these dioxygen species undergo skeletal rearrangement to 3-hydro ...[more]

PMID: 28970928

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