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. 2024 Nov 1;26(43):9173-9178.
doi: 10.1021/acs.orglett.4c02708. Epub 2024 Aug 30.

Electron Donor-Acceptor Complex-Enabled Autoinductive Conversion of Acylnitromethanes to Acylnitrile Oxides in a Photochemical Machetti-De Sarlo Reaction: Synthesis of 5-Substituted 3-Acylisoxazoles

Piyaporn Arunkirirote  1 , Pornteera Suwalak  1 , Nattawadee Chaisan  2 , Jumreang Tummatorn  1   2   3 , Somsak Ruchirawat  1   2   3 , Charnsak Thongsornkleeb  1   2   3
Affiliations

Electron Donor-Acceptor Complex-Enabled Autoinductive Conversion of Acylnitromethanes to Acylnitrile Oxides in a Photochemical Machetti-De Sarlo Reaction: Synthesis of 5-Substituted 3-Acylisoxazoles

Piyaporn Arunkirirote et al. Org Lett. .

Abstract

A photochemical Machetti-De Sarlo reaction has been developed for preparing 5-substituted 3-acylisoxazoles from acylnitromethanes and terminal alkynes. This photochemical protocol utilizes an innovative electron donor-acceptor complex, generated in situ from acylnitromethanes, catalytic LiOtBu, and 1,1,1,3,3,3-hexafluoro-2-propanol, as a photosensitizer to promote rapid conversion with a broad substrate scope in up to 80% efficiency. A sigmoidal autoinductive kinetic profile is revealed, demonstrating the novel and unique dual catalysis in the first photochemical approach of this reaction.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Scheme 1
Scheme 1. First Photochemical Machetti–De Sarlo Reaction
Scheme 2
Scheme 2. Scope of the Reaction
Yields of isolated products. Complex mixture.
Scheme 3
Scheme 3. (a) Reactions of Acylnitromethanes 1 with Other Dipolarophiles, (b) Reactions with Reversed Stoichiometries of Compounds 1 and 2, (c) Reaction in Millimole Scale, and (d) Radical-Trapping Experiments
Yields of isolated products. Complex mixture. Reaction was incomplete. BRSM = based on recovered starting material.
Figure 1
Figure 1
UV–vis absorption spectra of various compositions in HFIP.
Scheme 4
Scheme 4. Proposed Mechanism of the Photochemical Machetti–De Sarlo Reaction
See this image and copyright information in PMC

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