Abstract A series of new substituted gem-dibromospiropentanes was studied in a reaction with methyllithium at− 55...− 50° C. This reaction is a carbenoid rearrangement that leads to the formation of monomeric and dimeric bromocyclobutenes and also to the products of cyclobutylidene insertion into a CH bond of the solvent depending on the character of substituents in the dibromospiropentane fragment.
![10,10-dibromodispiro[2.0.54.13]decane Structure](https://image.chemsrc.com/caspic/037/88466-18-6.png)