Phosphoric amides. Part 11. Intramolecular reactivity of phosphorotriamidates

Abstract

Five N-(2-chloroethyl)phosphorotriamidates, (RNH)2P(O)NHCH2CH2Cl, have been synthesized, and their behavior under strongly basic conditions was studied. For N-alkyl derivatives (R = Me, PhCH2), base-promoted intramolecular displacement of chloride yielded the N-phosphorylated aziridine, (RNH)2P(O)NC2H4, as the exclusive cyclization product. For N-aryl derivatives (R = Ar), both the aziridine and the 1,3,2-diazaphospholidine, [Formula: see text], products could be obtained in comparable yields. The N-aromatic cyclic products are mutually interconvertible: 1,3,2-diazaphospholidines rearrange to the corresponding aziridines upon treatment with base, while bromide ions catalyze the reverse isomerization. Key words: phosphoramidates acidity, N-phosphorylated aziridines – 1,3,2-diazaphospholidines isomerization, 1,3 vs. 1,5 cyclization.