Indol-2-one derivatives (I) and their acid or base addition salts, hydrates or solvates are new. Indol-2-one derivatives of formula (I) and their acid or base addition salts, hydrates or solvates are new. dotted line : simple or double bond； X : CH, N or C； Y1 : N or CH； Ar : aryl or heteroaryl (optionally substituted by one or more substituents comprising halo, alkoxy, aryl, perhaloalkyl or alkyl)； R1 : H or -C(=O)alkyl, -C(=O)aryl or alkyl； R2-R4 : H, halo, alkyl, perhaloalkyl, CN, aryl, heteroaryl, OH, alkoxy, perhaloalkoxy, aminocarbonyl, alkylaminocarbonyl or dialkylaminocarbonyl； R5 : alkyl； and n : 1 or 2. Provided that at least one of: X, Y1 is N； and R2-R4 are H. Independent claims are included for: (1) the preparations of (I)； (2) a halo substituted indol-2-one compound of formula (III)； (3) alkyl substituted 1,3-dihydro-indol-2-one compound of formula (XXVIII)； and (4) a halo substituted indol-2-one compound of formula (XXIX). Hal, Hal2 : halo； and Alk : alkyl. [Image] [Image] ACTIVITY : Anorectic； Antidiabetic； Anorectic. MECHANISM OF ACTION : Growth hormone secretagogue receptor-1a antagonist. The ability of (I) to antagonize growth hormone secretagogue receptor-1a was tested in rats. The result showed that (+)N-[4,6-dichloro-3-(4-trifluoromethyl-phenyl)-2-oxo-2,3-dihydro-1H-indol-3-yl]-2-(4-ethyl-piperidin-1-yl)-acetamide exhibited an IC 5 0value of 1x 10 ->； 9>；M.
