Abstract
The reaction of 5-amino-4-cyanoformimidoylimidazoles 1a and 1b with tosyl isocyanate proved to be a mild and efficient method for the synthesis of the corresponding 6-amidino-2-oxopurines 5. These compounds, which were isolated in almost quantitative yield, rearrange in the presence of acetic acid–DMF to give a pyrimido[5,4-d]pyrimidin-2-one 6. The structure of compound 6 was confirmed by X-ray crystallography. The pathway for both reactions is discussed. Studies on the reactivity of tosyl isocyanate with imidazoles 2, 7, 8 and 16, obtained from 1 by selective acylation of the amino or imino nitrogen atoms, enabled clarification of the mechanism for purine formation.
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Schedule a callMore From: Journal of the Chemical Society, Perkin Transactions 1
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