Ligand libraries for screening GPCRs

A compound of general formula (III)

• wherein:
• X is —CO—(Y)k—(Z)n or SO2—(Y)k—(Z)n;
• k is 0 or 1;
• Y is a cycloalkyl or polycyloalkyl group;
• or Y is a cycloalkenyl or polycycloalkenyl group;
• each Z is independently selected from hydrogen, or an alkyl, haloalkyl, alkoxy, haloalkoxy, alkenyl, alkynyl, alkylamino, alkylaminoalkyl, alkylaminodialkyl, charged alkylaminotrialkyl or charged alkylcarboxylate radical of 1 to 20 carbon atoms;
• or each Z is independently selected from fluoro, chloro, bromo, iodo, hydroxy, oxyalkyl, amino, aminoalkyl, aminodialkyl, charged aminotrialkyl, or carboxylate radical;
• and
• n is any integer from 1 to m, where m is the maximum number of substitutions permissible on the cyclo-group Y;
• or
• each Z may be independently a peptido radical;
• and
• wherein R2 is an alkyl, aryl or an acyl group;
• and wherein R3 is a side-chain of an α-amino acid used in formation of (III);
• and wherein R4 is a 2-substituent of a β-amino alcohol used in formation of (III).