The wikipedia page on cyclononatetraene says that the aromatic cyclononatetraenyl anion can be synthetised by a rearangement of 9-chlorobicyclo[6.1.0]nona-2,4,6-triene.
My first idea on how to synthetise this compound is to react cyclooctatetraene with chlorocarbene $(\ce{:\!CHCl})$. However, in contrast to dichlorocarbene $(\ce{:\!CCl2})$, chlorocarbene $(\ce{:\!CHCl})$ is much less stable. Can it be synthetised by an action of a strong base on dichloromethane?
It seems, from this pdf, that $t$-$\ce{BuOK}$ will make $\ce{:\!CPhCl}$ from $\ce{CHPhCl2}$. Is it, however, a strong enough base to deprotonate $\ce{CH2Cl2}$? Or must some stronger one, e.g. LDA, be used?