In the presence of dienes, N-aryl-N'-hydroxyureas oxidized via mild copper(II) catalytic aerobic conditions are capable of undergoing hetero-Diels-Alder reactions to produce N-carbamoyl-3,6-dihydro-1,2-oxazine adducts. The thermal stability of these adducts has been found to be affected by the nature of the N-aryl-N'-carbamoylnitroso heterodienophile. Analysis by 1H NMR spectroscopy and colorimetric kinetics monitoring of the release a diene chromophore have revealed that electron-withdrawing character on the N-aryl ring significantly increases the rate of retrocycloaddition with subsequent decomposition. These findings may help develop adducts with customizable thermal decomposition thresholds for desirable applications involving the tuned release of molecular cargo. The reactions of 4-aryl-1,2,4-triazoline-3,5-diones have been considered in an analogous manner.

Substitution effects of<i> </i>nitroso and azo dienophiles on the rates of retro-hetero-Diels-Alder reactions

247th National Meeting (2014)

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Substitution effects of nitroso and azo dienophiles on the rates of retro-hetero-Diels-Alder reactions