Further evidence on the favorable role of the anomeric effect on the cleavage of HepDirect and cyclophosphamide prodrugs.

On the basis of previous conformational and configurational studies of 4-aryl-substituted cyclophosph(on)ates derived from d-xylofuranose derivatives, wherein it was proposed that the anomeric effect is involved in the spontaneous isomerization of the P atom and the C4 carbon, and consequently, this unusual behavior was associated with the cleavage of the HepDirect prodrugs. We synthesized an analogous series of 2-amino-2-oxo-1,3,2-dioxaphosphorinanes and performed a conformational and configurational analysis in solution and the solid state followed by an examination of their mutagenic activity. The results showed that the 2-amino-2-oxo-1,3,2-dioxaphosphorinanes with the largest mutagenic activity contain either a 4-methoxyphenyl or 4-fluorophenyl group at C4 carbon and presented a major chair conformation, which is prone to weaken the C4-O3 bond via the anomeric effect and facilitates the cleavage for the release of the biologically active metabolite.