Other than US Patent Application 'U2 2010/0191000' Methos for Synthesizing an N-unsubstituted or N-substituted Aziridine' & US 9,988,349 Direct Stereoselective Synthesis of unprotected aziridines from Olefins', I cannot find any papers that convert a non-terminal alkene (like cyclopropene) to N-methyl aziridines.
The reagent that seems the most specific and the most useful is o-(2,4-dinitrophenol)-n-methylhydroxyamine (CAS 38100-39-9).
I am considering this as an intermediate in the production of 1-propenyl-2-methylamine cyclopropene.
For anyone wondering, using trimethylamine as solvent and propenyl chloride as reagent (the HCl will quickly producing trimethylamine hydrochloride) LOOKS like an efficient route. Most routes proceed via the epoxide but trans isomers can be an issue i.e. harder to extract the isomer that is wanted.