Biphenyl derivatives

A compound of formula:

• wherein
• R is hydrogen, lower alkyl, lower alkoxy, halogen, amino, —N(R6)2 or trifluoromethyl;
• R1 is hydrogen, lower alkoxy or halogen;
• R and R1 may be together —CH═CH—CH═CH—;
• R2 is halogen, lower alkyl or trifluoromethyl;
• R3 is hydrogen or lower alkyl;
• R4 is hydrogen or a cyclic tertiary amine, optionally substituted by lower alkyl;
• R5 is hydrogen, nitro, amino or —N(R6)2;
• R6 is hydrogen or lower alkyl;
• X is —(CH2)nO—;
• and
• n is 1 or 2;
• or a pharmaceutically acceptable acid addition salt thereof.