Compounds of formula (I) or a pharmaceutically acceptable salt thereof. wherein R is hydrogen or C1-4 alkyl; R1 is hydrogen, C1-4 alkyl, C(O)OH, C(O)NH2 or (C1-4 alkylene)R10; R2 and R3 are independently hydrogen, C1-4 alkyl or R2 together with R3 and together with the carbon atom to which they are attached form a C3-8 cycloalkyl group; R4 is C1-4 alkyl, C1-4 alkoxy or halogen; R5 and R7 are independently hydrogen, hydroxy, halogen, C(O)NH2, C(O)OH or (C1-4 alkylene)R10; R6 and R8 are independently hydrogen or halogen; R9 is hydrogen, (C1-4 alkylene)R10, C(O)NH2, C(O)OH or R9 together with R form a 6 membered heterocyclic ring optionally containing a further heteroatom selected from oxygen, sulphur or nitrogen; R10 is hydrogen, halogen, hydroxy, C(O)NH2, C(O)NH(C1-4 alkyl), C(O)N(C1-4 alkyl)2 or C(O)OH; n is 0, 1 or 2. processes for their preparation, to compositions containing them and to their use in the treatment of diseases and conditions for which antagonism of NK1 is beneficial.