Amidation by Formamide

Formamide is the most simple source of the carbamoyl radical [Eq. (21)] 

Hydroxy and alkoxy radicals, obtained from hydrogen peroxide or alkyl peroxides were used 57,58), Bond dissociation energies and polar effects preferentially promote the hydrogen abstraction from the C—H bond. However a hydrogen abstraction from the N—H bond would result without consequences because it would give rise to an electrophilic nitrogen-centered radical, unreactive towards proto-nated heteroaromatic bases. 

Some results are shown in Table 13. The variety of heteroaromatic bases which can be used, the high selectivity, the often good yields and the simple experimental conditions contribute to the synthetic interest of this substitution. The polysubstitution by carbamoyl radical has the same characteristics of the acylation because the amido group (CONHg) activates the heteroaromatic ring. 

Heterocyclic base Position of attack Conversion 0/ /o Yield % 

2) Yield based on starting heterocyclic base conversions were not determined. 

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