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DOI: 10.1055/s-0035-1561098
Photochemical and Additive-Free Coupling Reaction of α-Cumyl α-Keto Esters via Intermolecular C–H Bond Activation
Publikationsverlauf
Received: 26. November 2015
Accepted after revision: 14. Dezember 2015
Publikationsdatum:
04. Januar 2016 (online)
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Abstract
We developed a photo-chemical coupling reaction of α-keto esters with several simple alcohols, alkanes, ethers, and amides. Use of tertiary alkyl ester, α-cumyl ester, is the key for avoiding the known photo-degradation process. Intermolecular C–H bond activation and subsequent C–C bond formation were promoted by irradiation with an LED lamp (365 nm) without any additives. Among the coupling partners, reactions with sterically less demanding amides proceeded efficiently to provide unique N-acyl-β-amino-α-hydroxy acid derivatives. In benzene or acetone as a solvent, the reaction with a solid amino acid derivative provided a precursor of tetrahydro-1,4-diazepine-2,5-dione derivatives.
Key words
photo-chemical reaction - α-keto esters - coupling reactions - C–H bond activation - β-amino acid derivatives - α-cumyl esters - tetrahydro-1,4-diazepine-2.5-dioneSupporting Information
- Supporting information for this article is available online at http://dx.doi.org/10.1055/s-0035-1561098.
- Supporting Information
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References and Notes
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Selected reviews on direct sp3 C–H bond functionalization, see:
Another type of degradation:
Some photo-induced [2+2] cycloadditions of α-keto esters have been reported. Representative examples:
Representative examples for photo-induced ‘intramolecular’ cyclization of α-keto esters via C–H bond activation:
Decarboxylative coupling of α-keto esters and low reactivity with 1,3-dithiane:
Representative recent examples for the preparation of N-acyl-β-amino-α-hydroxy acid derivatives with a tetrasubstituted carbon center:
No tetrahydro-1,4-diazepine-2.5-dione derivative with this substitution pattern has been reported. For similar examples, see:
Photo-induced alkylation of α-keto esters promoted by formation of boron-enolate or adding benzimidazolines as an electron-transfer reagent has been reported: