The retro-Diels Alder reaction has the potential to be a delivery method for molecular cargo upon the release and concomitant decomposition of a dienophile.  N-Aryl- and N-alkyl-N'-hydroxyureas were readily converted to heterodienophiles upon oxidation under copper(II) aerobic catalysis.  The in situ hetero-Diels-Alder reactions of these carbamoyl nitroso species with anthracenes, acyclic 1,3-butadienes, and alicyclic 1,3-dienes furnished the corresponding N-carbamoyl-3,6-dihydro-1,2-oxazines at 0-23 �C  in 61-98% yield. The novel 3,6-dihydro-1,2-oxazines can undergo a retro-Diels-Alder reaction with hydrolytic decomposition when heated (37-100 �C) under aqueous conditions.  The dienophile portion thereby releases the N-aryl or N-alkylamine, nitric oxide or nitroxyl, and carbon dioxide.   Proton nuclear magnetic resonance (1H NMR) spectrometry and UV-visible spectroscopy were utilized to measure the kinetic parameters for the decomposition.   Substitution of the dienes are assessed to determine which steric or electronic factors contribute to the threshold temperatures required for the retro-Diels-Alder decomposition pathway.

Temperature-dependent amine release tuned by diene substitution: The hydrolytic retro-Diels-Alder reactions of <i>N</i>-carbamoyl-3,6-dihydro-1,2-oxazines

245th National Meeting (2013)

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Temperature-dependent amine release tuned by diene substitution: The hydrolytic retro-Diels-Alder reactions of N-carbamoyl-3,6-dihydro-1,2-oxazines