Synthesis of the first representatives of 3-ethynyldiaziridines

1,2-Dimethyl-3-(3,3-diethoxypropyn-1-yl)-and 1,2-dimethyl-3-(3-hydroxymethyl-3-methylbutyn-1-yl)diaziridines have been synthesised by the interaction of 4,4-diethoxybutyn-2-al and 4-hydroxymethyl-4-methylpentyn-2-al, respectively, with equimolar amounts of MeNH₂ and MeNHCl (or MeNHOSO₃H) at pH 9.5–10; the use of an excess of an amine in reactions with 4,4-diethoxybutyn-2-al resulted in a mixture of isomeric 5(3)-diethoxymethyl-1-methylpyrazoles and a mixture of Z/E isomers of 1-cyano- 3,3-diethoxy-2-methylaminoprop-1-enes.