  We define and investigate a class of Koszul quasi-hereditary algebras for
which there is a natural equivalence between the bounded derived category of
graded modules and the bounded derived category of graded modules over (a
proper version of) the extension algebra of standard modules. Examples of such
algebras include, in particular, the multiplicity free blocks of the BGG
category $\mathcal{O}$, and some quasi-hereditary algebras with Cartan
decomposition in the sense of K{\"o}nig.
