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Abstract Stereoselective Zweifel olefination using boronate complexes carrying two different reactive π‐systems was achieved to synthesize vinyl heteroarenes and conjugated 1,3‐dienes in good yield and up to 100 % stereoselectivity, which remains unexplored until now. Most importantly, we report the unprecedented formation ofEvs.Z‐vinyl heteroarenes for different heteroarenes under identical conditions. Density functional theory (DFT) investigations unveil the mechanistic dichotomy between olefin and heteroarene activation followed by 1,2‐migration, leading toEorZ‐vinyl heteroarenes respectively. We also report a previously unknown reversal of stereoselectivity by using 2,3‐Dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) as an electrophile. The Zweifel olefination using a boronate complex that carries two different olefins was previously unexplored due to significant challenges associated with the site‐selective activation of olefins. We have solved this problem and reported the site‐selective activation of olefins for the stereoselective synthesis of 1,3‐dienes.
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Escape from Hydrofunctionalization: Palladium Hydride‐Enabled Difunctionalization of Conjugated Dienes and Enynes
Abstract Palladium hydrides are traditionally employed in hydrofunctionalization (i.e. monofunctionalization) of conjugated dienes and enynes, owning to its facile protic hydropalladation of electron‐rich (or neutral) unsaturated bonds. Herein, we report a mild PdH‐catalyzed difunctionalization of conjugated dienes and enynes. This protocol is enabled by the chemoselectivity switch of the initial hydropalladation step achieved by visible light enhancement of hydricity of PdH species. This method allows for cascade annulation of dienes and enynes with various easily available and abundant substrates, such as acrylic acids, acrylic amides, and Baylis–Hillman adducts, toward a wide range of alkenyl or alkynyl lactones, lactams, and tetrahydrofurans. This protocol also provides an easy access to complex spiro‐fused tricyclic frameworks.
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- Award ID(s):
- 2246075
- PAR ID:
- 10469366
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 62
- Issue:
- 47
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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