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Abstract α‐substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in natural products and pharmaceuticals. We report the α‐acetylation of C(sp3)−H substrates R−H with arylmethyl ketones ArC(O)Me to provide α‐alkylated ketones ArC(O)CH2R at RT withtBuOOtBu as oxidant via copper(I) ‐diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α‐substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [CuII](CH2C(O)Ar) that capture alkyl radicals R• to give R−CH2C(O)Ar outcompeting dimerization of the copper(II) enolate to give the 1,4‐diketone ArC(O)CH2CH2C(O)Ar.
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Regiocontrol via Electronics: Insights into a Ru‐Catalyzed, Cu‐Mediated Site‐Selective Alkylation of Isoquinolones via a C−C Bond Activation of Cyclopropanols
Abstract A site‐selective C(3)/C(4)‐alkylation ofN‐pyridylisoquinolones is achieved by employing C−C bond activation of cyclopropanols under Ru(II)‐catalyzed/Cu(II)‐mediated conditions. The regioisomeric ratios of the products follow directly from the electronic nature of the cyclopropanols and isoquinolones used, with electron‐withdrawing groups yielding predominantly the C(3)‐alkylated products, whereas the electron‐donating groups primarily generate the C(4)‐alkylated isomers. Density functional theory calculations and detailed mechanistic investigations suggest the simultaneous existence of the singlet and triplet pathways for the C(3)‐ and C(4)‐product formation. Further transformations of the products evolve the utility of the methodology thereby yielding scaffolds of synthetic relevance.
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- Award ID(s):
- 2154083
- PAR ID:
- 10452713
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 29
- Issue:
- 55
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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