  We study the centrally generated primitive ideals of $U(\mathfrak{n})$, where
$\mathfrak{n}$ is the (locally) nilpotent radical of a (splitting) Borel
subalgebra of a simple complex Lie algebra
$\mathfrak{g}=\mathfrak{o}_{2n+1}(\mathbb{C})$,
$\mathfrak{o}_{2n}(\mathbb{C})$, $\mathfrak{o}_{\infty}(\mathbb{C})$. In the
infinite-dimensional setting, there are infinitely many isomorphism classes of
Lie algebras $\mathfrak{n}$, and we fix $\mathfrak{n}$ with "largest possible"
center of $U(\mathfrak{n})$. We characterize the centrally generated primitive
ideals of $U(\mathfrak{n})$ in terms of the Dixmier map and the Kostant
cascade.
