Piperidine derivatives with PAF antagonist activity

A compound of formula I:

• ##STR12## wherein:
• m represents 0, 1 or 2;
• a, b and c represent CR, wherein each R independently represents hydrogen or C.sub.1-4 alkyl;
• R.sup.1 represents C.sub.1-4 alkyl or C.sub.3-7 cycloalkyl;
• A represents --CO--, --SO.sub.2 --, --NHCO-- or --OCO--;
• B represents a group of formula (i), and when A represents --CO-- or --SO.sub.2 --, then B can also represent a group of formula (ii) or (iii) ##STR13## n represents 0, 1, 2 or 3;
• one of R.sup.2 or R.sup.3 represents C.sub.1-4 alkyl, C.sub.3-7 cycloalkyl or aryl, and the other represents hydrogen, C.sub.1-4 alkyl, C.sub.1-4 haloalkyl, C.sub.3-7 cycloalkyl, C.sub.1-4 alkoxy-C.sub.1-4 alkyl, aryl or aryl-C.sub.1-4 alkyl;
• Z represents hydrogen, C.sub.1-4 alkyl, --CH.sub.2 --OR.sup.4, --COOR.sup.4 or --CONR.sup.4 R.sup.5, and when A represents --CO-- or --SO.sub.2 --, then Z can also be hydroxy, --NR.sup.4 R.sup.5, --NR.sup.6 C(.dbd.O)OR.sup.4, --NR.sup.6 C(.dbd.O)R.sup.4, --NR.sup.6 C(.dbd.O)NR.sup.4 R.sup.5, --N(OH)C(.dbd.O)NR.sup.4 R.sup.5 or --NR.sup.6 SO.sub.2 R.sup.4 ;
• or Z and R.sup.3 together form a C.sub.2-5 polymethylene chain in which case R.sup.2 represents C.sub.1-4 alkyl, C.sub.3-7 cycloalkyl or aryl;
• R.sup.4 represents hydrogen, C.sub.1-4 alkyl, aryl or aryl-C.sub.1-4 alkyl;
• R.sup.5 and R.sup.6 independently represent hydrogen or C.sub.1-4 alkyl;
• R.sup.7 represents C.sub.1-4 alkyl, C.sub.3-7 cycloalkyl, aryl, aryl-C.sub.1-4 alkyl or bisaryl-C.sub.1-4 alkyl;
• Y represents hydrogen, C.sub.1-4 alkyl, aryl, aryl-C.sub.1-4 alkyl, --C(.dbd.O)OR.sup.4, --C(.dbd.O)R.sup.4, --C(.dbd.O)NR.sup.4 R.sup.5, or --SO.sub.2 R.sup.4 ;
• aryl, whenever appearing in the above definitions, represents phenyl or phenyl substituted with 1, 2, 3 or 4 groups independently selected from halogen, C.sub.1-4 alkyl, C.sub.1-4 alkoxy, hydroxy, C.sub.1-4 haloalkyl, C.sub.1-4 haloalkoxy, cyano, nitro, amino, C.sub.1-4 alkylamino, C.sub.1-4 dialkylamino, C.sub.1-4 alkylcarbonyl, C.sub.1-4 alkylcarbonyloxy, C.sub.1-4 alkoxycarbonyl, C.sub.1-4 alkylsulfonyl, C.sub.1-4 alkylsulfinyl, C.sub.1-4 alkylthio, C.sub.1-4 alkylcarbonylamino or C.sub.1-4 alkoxycarbonylamino;
• and the salts and solyates thereof.