  We consider exotic baryons with hidden charm as antiquark-diquark-diquark
composite systems. Spin and isospin structure of such exotic states is given
and masses are estimated. The data for production of pentaquarks in the
reaction $\Lambda_b\to K^-p J/\psi$ are discussed. We suggest that the narrow
peak in $pJ/\psi$ spectra at 4450 MeV is antiquark-diquark-diquark state with
negative parity, $5/2^{-}(4450)$, while the broad bump $3/2^{+}(4380)$ is the
result of rescatterings in the ($pJ/\psi$)-channel. Positions of other
pentaquarks with negative parity are estimated.
