Beilstein J. Org. Chem.2011,7, 127–134, doi:10.3762/bjoc.7.18
-1,4-diketones after hydrolysis of the primary photochemical products (photo aldol reaction) [7], whilst the reaction of oxazoles with carbonyl compounds is a convenient protocol for the stereoselective synthesis of α-amino β-hydroxy ketones [8][9] as well as highly substituted α-amino β-hydroxy acids
reagent on the liberated benzaldehyde.
Conclusion
The photocycloaddition of electronically excited carbonyl compounds to isoxazoles is clearly less effective than with other five-membered aromatic or non-aromatic heterocycles (furans, thiophenes, pyrroles, oxazoles, dihydrofurans, dihydropyrroles) [1
Beilstein J. Org. Chem.2006,2, No. 21, doi:10.1186/1860-5397-2-21
. As expected, oxazoles, thiazoles, pyrazoles, and pyridines are tolerated in this chemistry. In a limited number of cases, functionality (e.g. basic amines, benzimidazoles, indoles, etc.) caused no reaction to occur and only recovered starting materials were isolated (data not shown).
We then shifted
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Graphical Abstract
Figure 1:
Thiazolidine-2,4-dione mimic & chosen lead scaffold.