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. 2023 Aug 20;3(5):312-320.
doi: 10.1021/acsorginorgau.3c00028. eCollection 2023 Oct 4.

Gold(I)-Catalyzed 1,6-Enyne Single-Cleavage Rearrangements: The Complete Picture

Eduardo García-Padilla  1   2 , Feliu Maseras  1   2 , Antonio M Echavarren  1   2
Affiliations

Gold(I)-Catalyzed 1,6-Enyne Single-Cleavage Rearrangements: The Complete Picture

Eduardo García-Padilla et al. ACS Org Inorg Au. .

Abstract

We identify the factors that rule the selectivity in single-cleavage skeletal rearrangements promoted by gold(I) catalysts. We find that stereoconvergence is enabled by a rotational equilibrium when electron-rich substituents are used. The anomalous Z-selective skeletal rearrangement is found to be due to electronic factors, whereas endo-selectivity depends on both steric and electronic factors.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Scheme 1
Scheme 1. (a) Single versus Double Skeletal Rearrangement of 1,6-Enynes. (b) Tether Dependence on exo- and endo-Selectivity
Scheme 2
Scheme 2. (a) Examples of E-Selective or Stereospecific Single-Cleavage Skeletal Rearrangement and (b) Abnormal Z-Selective Single-Cleavage Skeletal Rearrangement
Scheme 3
Scheme 3. (a–f) Gold(I)-Catalyzed 1,6-Enyne Single-Cleavage Skeletal Rearrangements
Scheme 4
Scheme 4. Mechanism of the Gold(I)-Catalyzed Z-Selective exo-Single-Cleavage Skeletal Rearrangement of E-7h and Z-7h
Free energy in kcal/mol.
Figure 1
Figure 1
Model for the 1,3-sigmatropic shift in the transition state as a formal cyclobutonium cation. Cleavage of the single bond results in a carbene migrating across an allyl cation.
Scheme 5
Scheme 5. Formation of Bicyclo[3.2.0]heptenes is Not Feasible from These Substrates
Scheme 6
Scheme 6. Model Showing Competition between Internal Rotation and exo-Migration of Different Enynes Using [JohnPhosAu] as a Catalyst
Figure 2
Figure 2
Lewis structure of the transition state used in NBO analysis and 3D rendition showing the bicyclobutonium geometry.
Scheme 7
Scheme 7. Mechanism of the Gold(I)-Catalyzed exo- and endo-Single-Cleavage Skeletal Rearrangements of N-Propargyl-N-(p-methoxycinnamyl)methanesulfonamide,
Free energy in kcal/mol. Formation of the initial gold(I) cyclopropyl carbene (blue) can be found in the Supporting Information.
See this image and copyright information in PMC

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