Synthesis and Reactivity of 1‑Allenyltriazenes

1-Aryl-3,3-dialkyltriazenes
have received considerable attention
in the context of synthetic and medicinal chemistry. In contrast,
the chemistry of other unsaturated triazenes is largely unexplored.
The synthesis of 1‑allenyl­triazenes is described. This
new class of compounds can be obtained by base-induced isomerization
of 1‑alkynyl­triazenes. The latter are accessible by reaction
of alkynyl Grignard reagents with lithium amides and nitrous oxide.
1-Allenyltriazenes were found to be thermally labile, but they can
be stored without degradation at lower temperatures. In the presence
of ZnCl2, 1-allenyltriazenes rearrange into N‑amino­pyrazoles.