Selective acylation of 4,5-diamino-9,9′-dimethylxanthene through an aggregation effect

The proximity of the 4,5-diamino groups in a 9,9′-dimethylxanthene skeleton provides unique reactivity due to aggregation effects. While treatment with 1 equiv of an isocyanate yields the diurea and starting material, under similar conditions, Boc2O provides essentially only the monocarbamoyl derivative.

The proximity of the 4,5-diamino groups in a 9,9′-dimethylxanthene skeleton provides unique reactivity due to aggregation effects. While treatment with 1 equiv of an isocyanate yields the diurea and starting material, under similar conditions, Boc2O essentially provides the monocarbamoyl derivative.