Reactivity of dimesitylfluorenylidenegermane with unsaturated nitrogen compounds

Article abstract of DOI:10.1021/om00050a054

Dimesitylfluorenylidenegermane (1) reacts with ethylbenzylideneamine (PhCH=NEt) to give, according to a [2 + 2] cycloaddition, the very thermally stable four-membered-ring germaazetidine 2. In contrast, imines with a NH function, such as (diphenylmethylidene)amine (Ph₂C=NH), react only as protic reagents. A [2 + 4] cycloaddition is observed with azobenzene, affording 5, which slowly aromatizes to 6 or thermally rearranges to give the [2 + 2] cycloadduct germadiazetidine 7. In the case of nitrosobenzene, only the germanone dimer 17 and imine 9 have been observed, probably via the preliminary formation of transient four-membered heterocycle 15.