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Abstract A variety of 1‐aryl‐1,3‐dienes were isomerized fromEtoZisomers by photocatalysis using Ru(bpy)3[PF6]2and blue LED light. Enrichment of theZ‐isomer is thought to occur by selective triplet energy transfer from the photocatalyst to the stereoisomeric mixture. The 1,3‐diene starting materials are easily made by catalytic ene‐yne metathesis (EYM). To access 1,3‐dieneZ‐stereoisomers directly, a one pot procedure was developed. Additional 1,3‐dienes were investigated for both isomerization andZ‐enrichment. The combination of cross EYM with photocatalysis allows for the stereoconvergent synthesis ofZ‐1,3‐dienes.
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Stereodivergent Zweifel Olefination and its Mechanistic Dichotomy
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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- Award ID(s):
- 2154083
- PAR ID:
- 10503380
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 62
- Issue:
- 38
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/anie.202309136
