Acyliminium ions and related species are potent electrophiles that can be quite valuable in the synthesis of nitrogen‐containing molecules. This manuscript describes a protocol to form these intermediates through hydride abstractions of easily accessible allylic carbamates, amides, and sulfonamides that avoids the reversibility that is possible in classical condensation‐based routes. These intermediates are used in the preparation of a range of nitrogen‐containing heterocycles, and in many cases high levels of stereocontrol are observed. Specifically areas of investigation include the impact of chemical structure on oxidation efficiency, the geometry of the intermediate iminium ions, the impact of a substrate stereocenter on stereocontrol, and an examination of transition state geometry.
Enantioselective Alkynylation of Unstabilized Cyclic Iminium Ions
An enantioselective copper-catalyzed alkynylation of unstabilized cyclic iminium ions has been developed. Whereas such alkynylations typically utilize pyridinium, quinolinium and isoquinolinium intermediates, this method enables use of cyclic iminium ions unstabilized by resonance. With the use of a Lewis acid and copper catalyst, these iminium ions are generated in situ from readily available hemiaminal methyl ethers and transformed into highly enantioenriched ⍺-alkynylated cyclic amines. A variety of terminal alkynes can be incorporated in high yields and enantiomeric excesses.
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- Award ID(s):
- 1664981
- PAR ID:
- 10202751
- Date Published:
- Journal Name:
- ACS Catalysis
- Volume:
- 10
- ISSN:
- 2155-5435
- Page Range / eLocation ID:
- 13820 to 13824
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acscatal.0c04223
