Pyrrolidines as dipeptidyl peptidase inhibitors

A compound of formula (I):

• 14
• including salts, solvates, and pharmaceutically functional derivatives thereof, wherein
• X is —S(O)b— or —CH2—;
• b is 0-2;
• R1 and R2 each are either
• (i) H;
• (ii) alkyl;
• (iii) optionally substituted aryl or heteroaryl;
• or
• (iv) combine to form a 3 to 14 membered ring sytem, optionally containing one or more heteroatoms, and optionally containing one or more degrees of unsaturation;
• when R1 and R2 are (iii), then R3 is H or alkyl;
• when R1 and R2 are (i), (ii), or (iv), then R3 is
• 15
• where n is 0-5;
• m is 0 to 12;
• Y is S(O)p, O, alkylene, alkenylene, alkynylene, or a bond;
• p is 0-2;
• R4 is R5 when Y is S, O, alkylene, alkenylene, alkynylene, or a bond, where R5 is alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heteroaryl, or heterocyclyl;
• R4 is R6 when Y is S(O) or S(O)2, where R6 is alkyl, aryl, cycloalkyl, heteroaryl, amino, alkylamino, arylamino, heteroarylamino, or cycloalkylamino.