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Catalysis of Radical Cyclizations from Alkyl Iodides under H₂: Evidence for Electron Transfer from [CpV(CO)₃H]^.

ABSTRACT: Radical cyclizations are most often achieved with Bu₃SnH in the presence of a radical initiator, but environmental considerations demand that alternative reagents be developed-ones that can serve as a synthetic equivalent to the hydrogen atom. We have revisited [CpV(CO)₃H]^-, a known replacement for Bu₃SnH, and found that it can be used catalytically under H₂ in the presence of a base. We have carried out tin-free catalytic radical cyclizations of alkyl iodide substrates. The reactions are atom-efficient, and the conditions are mild, with broad tolerance for functional groups. We have, for example, achieved the first 5-exo radical cyclization involving attack onto a vinyl chloride. We suggest that the radicals are generated by an initial electron transfer.

SUBMITTER: Kuo JL

PROVIDER: S-EPMC6373875 | biostudies-literature | 2018 Apr

REPOSITORIES: biostudies-literature

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Catalysis of Radical Cyclizations from Alkyl Iodides under H2: Evidence for Electron Transfer from [CpV(CO)3H].

Kuo Jonathan L JL Lorenc Chris C Abuyuan Janine M JM Norton Jack R JR

Journal of the American Chemical Society 20180321 13

Radical cyclizations are most often achieved with Bu3SnH in the presence of a radical initiator, but environmental considerations demand that alternative reagents be developed-ones that can serve as a synthetic equivalent to the hydrogen atom. We have revisited [CpV(CO)3H]-, a known replacement for Bu3SnH, and found that it can be used catalytically under H2 in the presence of a base. We have carried out tin-free catalytic radical cyclizatio ...[more]

PMID: 29543448

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