W is N or N⁺—O⁻;

R¹ and R⁵ are independently H, C₁ to C₆ alkyl, (C₁ to C₆ alkyl)oxy, mercapto, (C₁ to C₆ alkyl)mercapto, carboxy, carboxy(C₁ to C₆ alkyl), formyl, (C₁ to C₆ alkyl)carbonyl, (C₁ to C₆ alkyl)oxycarbonyl, (C₁ to C₆ alkyl)carbonyloxy, nitro, trihalomethyl, hydroxy, hydroxy(C₁ to C₆ alkyl), amino, (C₁ to C₆ alkyl)amino, di(C₁ to C₆ alkyl)amino, aminocarbonyl, halo, halo(C₁ to C₆ alkyl), aminosulfonyl, (C₁ to C₆ alkyl)sulfonylamino, (C₁ to C₆ alkyl)aminocarbonyl, di(C₁ to C₆ alkyl)aminocarbonyl, [N-Z](C₁ to C₆ alkyl)carbonylamino, formyloxy, formamido, (C₁ to C₆ alkyl)aminosulfonyl, di(C₁ to C₆ alkyl)aminosulfonyl, [N-Z](C₁ to C₆ alkyl)sulfonylamino or cyano; or R¹ and R⁵ together form a methylenedioxy group;

R² is H or a C₁ to C₁₈ alkyl, alkenyl, alkynyl, cycloalkyl, polycycloalkyl, cycloalkenyl, or aryl group, or a combination thereof, optionally substituted with 1, 2, or 3 -L-Q² groups up to three C atoms of each alkyl, alkenyl, alkynyl, cycloalkyl, polycycloalkyl, cycloalkenyl, or aryl group may optionally be replaced by N, O and/or S atoms;

R³ is —(CR¹¹R¹²)_m—X—(CR¹³R¹⁴)_p—R⁹;

m is 0, 1, 2, 3 or 4;

p is 0, 1 or 2;

X is a bond, —CR¹⁵═CR¹⁶—, —C≡C—, C(O)NH, NHC(O), C(O)NMe, NMeC(O), C(O)O, NHC(O)NH, NHC(O)O, OC(O)NH, NH, O, CO, SO₂, SO₂NH, C(O)NHNH,

R⁹ is H; C₁ to C₆ alkyl; or phenyl, naphthyl, pyridyl, benzimidazolyl, indazolyl, quinolinyl, isoquinolinyl, tetrahydroisoquinolinyl, indolinyl, isoindolinyl, indolyl, isoindolyl or 2-pyridonyl substituted with

-L-Q

wherein:

L is a bond, or a group of the formula —(CR¹⁷R¹⁸)_v—Y—(CR¹⁷R¹⁸)_w, wherein v and w are independently 0, 1, 2 or 3, and Y is a bond, —CR¹⁵═CR¹⁶—, phenyl, furanyl, thiophenyl, pyrrolyl, thiazolyl, imidazolyl, oxazolyl, isoxazolyl, pyrazolyl, isoxazolonyl, piperazinyl, piperidinyl, morpholinyl, pyrrolidinyl, isothiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, pyridyl or pyridazyl; and

Q is 5-oxo-2,5-dihydro[1,2,4]oxadiazolyl;

Q² is H, (C₁ to C₆ alkyl)oxy, [N-Z](C₁ to C₆ alkyl)oxy(C₁ to C₆ alkyl)amino, mercapto, (C₁ to C₆ alkyl)mercapto, carboxy(C₁ to C₆ alkyl)thiol, carboxy, carboxy(C₁ to C₆ alkyl), carboxy(C₁ to C₆ alkenyl), [N-Z]carboxy(C₁ to C₆ alkyl)amino, carboxy(C₁ to C₆ alkyl)oxy, formyl, (C₁ to C₆ alkyl)carbonyl, (C₁ to C₆ cycloalkyl)carbonyl, (C₁ to C₆ alkyl)oxycarbonyl, (C₁ to C₆ alkyl)carbonyloxy, nitro, trihalomethyl, hydroxy, amino, [N-Z](C₁ to C₆ alkyl)amino, aminocarbonyl, (C₁ to C₆ alkyl)aminocarbonyl, di(C₁ to C₆ alkyl)aminocarbonyl, [N-Z](C₁ to C₆ alkyl)carbonylamino, C₅ to C₈ cycloalkyl, [N-Z](C₁ to C₆ alkyl)carbonyl(C₁ to C₆ alkyl)amino, halo, halo(C₁ to C₆ alkyl), sulfamoyl, [N-Z](C₁ to C₆ alkyl)sulfonylamino, (C₁ to C₆ alkyl)sulfonylaminocarbonyl, carboxy(C₁ to C₆ alkyl)sulfonyl, carboxy(C₁ to C₆ alkyl)sulfinyl, tetrazolyl, [N-Z]tetrazolylamino, cyano, amidino, amidinothio, SO₃H, formyloxy, formamido, C₃ to C₈ cycloalkyl, (C₁ to C₆ alkyl)sulphamoyl, di(C₁ to C₆ alkyl)sulphamoyl, (C₁ to C₆ alkyl)carbonylaminosulfonyl, 5-oxo-2,5-dihydro[1,2,4]oxadiazolyl, carboxy(C₁ to C₆ alkyl)carbonylamino, tetrazolyl(C₁ to C₆ alkyl)thio, [N-Z]tetrazolyl(C₁ to C₆ alkyl)amino, 5-oxo-2,5-dihydro[1,2,4]thiadiazolyl, 5-oxo-1,2-dihydro[1,2,4]triazolyl, [N-Z](C₁ to C₆ alkyl)amino(C₁ to C₆ alkyl)amino, or a group of the formula

P is O, S or NR¹⁹;

Z is H, C₁ to C₆ alkyl, t-butoxycarbonyl, acetyl, benzoyl or benzyl;

R⁴ is H or a C₁ to C₁₈ alkyl, alkenyl, alkynyl, cycloalkyl, polycycloalkyl, cycloalkenyl, or aryl group, or a combination thereof, optionally substituted with 1, 2, or 3 -L-Q² groups wherein up to three C atoms of each alkyl, alkenyl, alkynyl, cycloalkyl, polycycloalkyl, cycloalkenyl, or aryl group may optionally be replaced by N, O and/or S atoms;

R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁷, R¹⁸ and R¹⁹ are independently H or C₁ to C₃ alkyl; and

R¹⁶ is H, C₁ to C₃ alkyl, or acetylamino.