The hetero-retro-Diels-Alder reaction of N-carbamoyl-3,6-dihydro-1,2-oxazines is of particular interest due to the hydrolytically unstable N-carbamoylnitroso dienophile which can decompose to release carbon dioxide, an amine, and nitric oxide (NO) or nitroxyl (HNO). The kinetic profile of this reaction is strongly affected by the identity of the diene.  Adducts formed from N-aryl-N'-hydroxyureas dienophile precursors are capable of decomposition in aqueous media at a wide range of temperatures (23-90 �C) depending on the diene identity.  The strain imposed by cyclic vs. acyclic dienes, steric factors, and the impact of electron-donating substituents have been assessed through monitoring the kinetics of decomposition by 1H NMR and UV-visible spectroscopic methods.   As nitroso species are known to be trienophiles for [6+2] reactions, the retro-cycloadditions of adducts formed from some substituted 1,3,5-cycloheptatrienes have been studied as well.  Diene-tuning can be used to customize the release of the heterodienophile or its breakdown products at various temperatures depending upon the desired application.

Diene and triene effects on the hetero-retro-cycloaddition reactions of adducts derived from <i>N</i>-carbamoylnitroso heteropolyenophiles

247th National Meeting (2014)

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Diene and triene effects on the hetero-retro-cycloaddition reactions of adducts derived from N-carbamoylnitroso heteropolyenophiles