N=6 Supergravity on $AdS_5$ and the $SU(2,2/3)$ Superconformal   Correspondence
  It is argued that N=6 supergravity on $AdS_5$, with gauge group $SU(3)\times U(1)$ corresponds, at the classical level, to a subsector of the ``chiral'' primary operators of N=4 Yang-Mills theories. This projection involves a ``duality transformation'' of N=4 Yang-Mills theory and therefore can be valid if the coupling is at a self-dual point, or for those amplitudes that do not depend on the coupling constant. 
S. Ferrara, M. Porrati and A. Zaffaroni