Res. Chem. Intermed.
, Vol. 33, No. 3–5, pp. 311–317 (2007)
Also available online - www.brill.nl/rci
A green approach to the amidation of heterocyclic bases:
the use of sunlight and air
, CRISTIAN GAMBAROTTI
, ANDREA MELE
, CARLO PUNTA
and FRANCESCO RECUPERO
Università di Bergamo, Facoltà di Ingegneria, Via Marconi 5, I-24044 Dalmine, Bergamo, Italy
Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”, Politecnico di Milano,
Via Mancinelli 7, I-20131 Milano MI, Italy
Received 26 October 2005; accepted 20 December 2005
Abstract—A easy and environmentally friendly method for the photochemical functionalisation of
the heterocyclic bases is described. The selective introduction of the amido group of formamide,
using sunlight and air in the presence of TiO
, has allowed to obtain the desired products in mild
conditions with high conversions. The comparison of these results with those previously reported, in
instead of air, clariﬁes some aspects of the reaction mechanism.
Keywords: Heterocyclic base; sunlight; TiO
The substitution of protonated heteroaromatic bases represents one of the most
important reactions for the synthesis of molecules of high pharmaceutical and
biological activity .
In the last decades many catalytic processes have been purposed for the selective
functionalization of heterocycles by the generation of nucleophilic carbon-centered
radicals, most of them based on the use of heavy metal salts both in stoichiometric
amounts as oxidant agents or as catalysts in the presence of oxygen or peroxides
[2–6]. Nowadays a greener route for the development of this key reaction is
necessary, due to an increased attention to the environmental impact and to the
mounting costs related to the dispose of chemical waste.
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