Synthesis of primary sec-alkylamines via nucleophilic ring-opening of N-phosphorylated aziridines

The novel ring-opening reaction of various 2-alkyl- and 2,2-dimethyl-N-(diethoxyphosphoryl)aziridines (I)and (In) with copper-modified Grignard reagents proceeds regiospecifically at the less hindered carbon. The diethyl N-sec-alkylphosphoramidates (2) thus obtained may efficiently be converted to primary sec-alkylamine hydrochlorides (3) by refluxing with 20% hydrochloric acid. 2,3-Disubstituted N-phosphorylated aziridines except N-phosphorylated cyclohexenimine (4) do not react under the described conditions. Copper-mediated reaction of 2-phenyl-N-(diethoxyphosphoryl)aziridine (7) with Grignard reagents affords a mixture of regioisomers (8) and (9) but still with the preference of ring-opening at the carbon of lesser substitution. (C) 1997 Elsevier Science Ltd.