Aminonitrenes synthesis

A -Amino- and A-substituted amino-pyrroles readily undergo Diels-Alder additions and add to activated alkynes at room temperature. The resulting azanorbornadienes extrude A-aminonitrenes and this forms the basis of an unusual synthesis of benzene derivatives (81S753,81TL3347). It has been found that ethyl/3-phenylsulfonylpropiolate (135) is a superior dienophile to DMAD (Scheme 50). 

Schultz, Dervan, and co-workers " subsequently reported the synthesis and characterization of the five-membered ring analogue 65. As before, the oxidation of the appropriate hydrazine at 78 °C gave a clear, colored solution of the aminonitrene. This 1,1-diazene absorbs at 497 nm (in CH2CI2) and 487 nm (in 2-propanol). The IR spectrum shows a strong absorption at 1638 cm that disappears on warming to 25 °C. The isotopomer has a vibration at 1612 cm a shift of 26 cm. ... 

The oxidation by lead(IV) acetate of iV-aminophthalimide and of several IV-aminolactams leads to the foimation of intermediates which do not undergo fragmentation or rearrangement, but which can be intercepted by alkenes, alkynes, sulfoxides and other nucleophiles. The reactions have proved particularly useful for e synthesis of aziridines from a variety of alkenes. The mechanism of these reactions has commonly been assumed to require the intermediacy of aminonitrenes, but this is probably not the case. Atkinson and Kelly have shown that oxidation of the aminolactam (25) by lead(FV) acetate at -20 C leads to the formation of an unstable IV-acetoxy compound. This is the species which can form aziridines with alkenes. The mechanism shown in Scheme 18, which is analogous to that for the epoxida-tion of alkenes by peroxy acids, has been proposed for the aziridination process. 

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