Nitrogen heterocycles containing carbonyl

The chemistry of highly electron deficient nitrogen heterocycles containing carbonyl groups is covered by Ana M. Costero of the University of Valencia, Spain, in the first overview of this interesting chemistry. 

The Chemistry of Unsaturated Nitrogen-Heterocyclic Compounds Containing Carbonyl Groups... 

The IR, NMR, and mass spectra of daphmacrine (18) suggest that it has a nitrogen heterocyclic skeleton similar to that of daphniphylline (1) but differs in the oxygen-containing moiety. The IR spectrum of this alkaloid showed two carbonyl bands at 1770 and 1730 cm-1 resulting from a five-membered lactone and an ester group, respectively. The NMR spectrum showed the presence of two tertiary methyl... 

Alcohols containing nitrogen heterocycles are also smoothly oxidized to the corresponding carbonyl compounds. These heterocycles include pyridine, imidazole and triazole derivatives. 

Rearrangement in nitrogen-containing carbonyl compounds merits brief discussion in this section as well as in Part III, Chapter 1. Type II photocyclizations are of particular value and have in the past been extensively used in the construction of nitrogen heterocycles. Competitive y- and 6-hydrogen abstractions have been observed in the a-alkyl-B-oxoamides (82), the former leading to benzoylacetamides (83) via Type II photoelimination and... 

C transitions, i.e. about 10-6 s. Such a slow process cannot compete with the dominant non-radiative processes. This explains the low fluorescence quantum yields of many molecules in which the lowest excited state is n-n in nature. This is the case for most azo compounds and some compounds containing carbonyl groups and nitrogen heterocycles (with pyridine-type nitrogens) (see Sections 3.4.2.3 and 3.4.3). 

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