Hydrazones aziridine synthesis

Phase-transfer catalytic conditions provide an extremely powerful alternative to the use of alkali metal hydrides for the synthesis of cyclopropanes via the reaction of dimethyloxosulphonium methylides with electron-deficient alkenes [e.g. 54-56] reaction rates are increased ca. 20-fold, while retaining high yields (86-95%). Dimethylphenacylsulphonium bromide reacts in an analogous manner with vinyl-sulphones [57] and with chalcones [58] and trimethylsulphonium iodide reacts with Schiff bases and hydrazones producing aziridines [59]. 

Ethylenimines or aziridines [lb] can be considered cyclic imines and are only briefly covered in Section 5. The preparation of heterocyclic imine systems, semicarbazones, hydrazones, azines, and oximes, is omitted from this chapter. The synthesis of carbodiimides is presented in Chapter 9. 

Synthesis of aziridines.11 Lead tetraacetate oxidation of certain 1,1-disubstituted hydrazones, for example, (1)—(3), in the presence of nucleophilic olefins commonly used as carbene traps, gives aziridines in fair to good yields. Presumably singlet... 

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