Black holes in five-dimensional Palatini $f(R)$ gravity and implications   for the AdS/CFT correspondence
  We show that theories having second-order field equations in the context of higher-dimensional modified gravity are not restricted to the family of Lovelock Lagrangians, but can also be obtained if no a priori assumption on the relation between the metric and affine structures of space-time is made (Palatini approach). We illustrate this fact by considering the case of Palatini $f(R)$ gravities in five dimensions. Our results provide an alternative avenue to explore new domains of the AdS/CFT correspondence without resorting to {\it ad hoc} quasi-topological constructions. 
D. Bazeia, L. Losano, Gonzalo J. Olmo, D. Rubiera-Garcia
hep-th