C. Leroux et al., PHOSPHORYLATED NITROGEN MUSTARDS - CYCLIZATION AND RING-OPENING OF PHOSPHORIC AND PHOSPHONIC N-(2-CHLOROETHYL)AMIDES, Journal of chemical research. Synopses, (9), 1993, pp. 372-373
Base-promoted 1,3-cyclization of phenyl N,N'-di-(2-chloroethyl)phospho
rodiamidate (1a) and N,N'-di-(2-chloroethyl)-P-phenylphosphonic diamid
e (1b) leading to the N-phosphorylated aziridines is complicated by th
e reversibility of the reaction due to the nucleophilic attack of Cl-
at the aziridynyl ring.