N-acyl-2-substituted-4-(benzimidazolyl-or imidazopyridinyl-substituted pesidues)-piperidines as tachykinin antagonists

N-heterocyclic compounds of formula (I), and their N-oxides, salts and isomers, are new. n = 0, 1 or 2; m = 1 or 2, provided that when m is 2, then n is 1; X = a bond, O, S or NR3; Q = O or NR3; R1 = Ar1, Ar1(1-6C alkyl) or di(Ar1)(1-6C alkyl), where the 1-6C alkyl groups are optionally substituted by OH, TO, oxo or a ketalised oxo substituent of formula OCH2CH2O or OCH2CH2CH2O; R2 = Ar2, Ar2(1-6C alkyl), Het or Het(1-6C alkyl); L = a group of formula (i) or (ii); p = 0, 1 or 2; Y, depending on whether the optional second bond is present or not, is (i) a bivalent radical of formula CH2, CH(OH), C(O), O, S, SO, SO2, NR3, CH2NR3 or CONR3, or (ii) a trivalent radical of formula CH; A=B is a bivalent radical of formula CH=CH, N=CH or CH=N; R3 = H or R; R4 = H, R, 3-7C cycloalkyl, Alk-R7 or Alk-Z-R8; Alk = 1-6C alkanediyl; Z = O, S or NR3; R7 = Ph (optionally substituted by 1-2 halo, R or RO); furanyl (optionally substituted by 1-2 R or hydroxy(1-6C alkyl)); thienyl (optionally substituted by 1-2 halo or R); oxazolyl, thiazolyl or pyridinyl (all optionally substituted by 1-2 R); R8 = R (optionally substituted by OH, COOH or COOR); R5 = H, halo, OH or RO; R6 = H, R or Ar1(1-6 alkyl); Ar1 = Ph (optionally substituted by 1-3 halo, T, T', CN, CONH2, TO or T'O); Ar2 = naphthalenyl, or Ph (optionally substituted by 1-3 OH, halo, CN, NO2, NH2, NHT, N(T)2, T, T', TO, T'O, COOH, COOT, CONH2, CONHT or CON(T)2); Het = pyrrolyl, pyrazolyl, imidazolyl, furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, quinolinyl, quinoxalinyl, indolyl, benzimidazolyl, benzoxazolyl, benzisoxazolyl, benzothiazolyl, benzisothiazolyl, benzofuranyl or benzothienyl (all optionally substituted on carbon by 1-2 halo, T or mono-, di- or tri(halo)methyl); T, T', R, = 1-4C alkyl, halo(1-4C alkyl), 1-6C alkyl respectively.