Nitrene Equivalent Mediated Metal-Free Ring Expansions of Alkylidenecyclopropanes and an Alkylidenecyclobutane

The ring expansion of small-ring compounds provides a powerful method for the construction of various cyclic compounds. Herein, nitrene
equivalent mediated metal-free ring expansions of alkylidenecyclopropanes (ACPs) and an alkylidenecyclobutane (ACB) were described. In
this synthesis, a series of aryl-substituted cyclobutylidene and cyclopentylidene hydrazine derivatives were obtained under mild conditions
in moderate to good yields.