the dashed line represents an optional bond,

X¹, X², and X³ are independently hydrogen, halogen, C₁-C₆ alkyl, C₁-C₆ haloalkyl, C₁-C₈ alkoxy, C₁-C₈ alkoxyalkyl, CN, NO₂, OR⁵, NR⁵R⁶, CO₂R⁵, COR⁵, S(O)_nR⁵, CONR⁵R⁶, NR⁵COR⁶, NR⁵SO₂R⁶, SO₂NR⁵R⁶, and P(O)(OR⁵)(OR⁶); with the proviso that at least one of X¹, X², and X³ must be hydrogen;

n=0-2;

R¹ is C₁-C₆ alkyl,

R² and R⁴ are independently selected from hydrogen, halogen, C₁-C₈ alkyl, C₃-C₇ cycloalkyl, C₁-C₈ alkoxy, C₁-C₈ alkoxyalkyl, C₁-C₈ haloalkyl, C₁-C₈ hydroxyalkyl, C₂-C₈ alkenyl, C₂-C₈ alkynyl, nitrile, nitro, OR⁵, SR⁵, NR⁵R⁶, N(O)R⁵R⁶, P(O)(OR⁵)(OR⁶), (CR⁵R⁶)_mNR⁷R⁸, COR⁵, (CR⁴R⁵)_mC(O)R⁷, CO₂R⁵, CONR⁵R⁶, C(O)NR⁵SO₂R⁶, NR⁵SO₂R⁶, C(O)NR⁵OR⁶, S(O)_nR⁵, SO₂NR⁵R⁶, P(O)(OR⁵)(OR⁶), (CR⁵R⁶)_mP(O)(OR⁷)(OR⁸), (CR⁵R⁶)_m-aryl, (CR⁵R⁶)_m-heteroaryl, -T(CH₂)_mQR⁵, —C(O)T(CH₂)_mQR⁵, NR⁵C(O)T(CH₂)_mQR⁵, and -CR⁵=CR⁶C(O)R⁷;

T is O, S, NR⁷, N(O)R⁷, NR⁷R⁸W, or CR⁷R⁸;

Q is O, S, NR⁷, N(O)R⁷, NR⁷R⁸W, CO₂, O(CH₂)_m-heteroaryl, O(CH₂)_mS(O)_nR⁸, (CH₂)-heteroaryl, or a carbocyclic group containing from 3-7 ring members, up to four of which ring members are optionally heteroatoms independently selected from oxygen, sulfur, and nitrogen, provided, however, that there is at least one carbon atom in the carbocyclic ring and that if there are two or more ring oxygen atoms, the ring oxygen atoms are not adjacent to one another, wherein the carbocyclic group is unsubstituted or substituted with one, two, or three groups independently selected from halogen, hydroxy, hydroxyalkyl, lower alkyl, lower alkoxy, alkoxycarbonyl, alkylcarbonyl, alkylcarbonylamino, aminoalkyl, trifluoromethyl, N-hydroxyacetamide, trifluoromethylalkyl, amino, and mono or dialkylamino;

W is an anion selected from the group consisting of chloride, bromide, trifluoroacetate, and triethylammonium;

m=0-6;

R⁴ and one of X¹, X² and X³ may form an aromatic ring containing up to three heteroatoms independently selected from oxygen, sulfur, and nitrogen, and optionally substituted by up to 4 groups independently selected from halogen, hydroxy, hydroxyalkyl, lower alkyl, lower alkoxy, alkoxycarbonyl, alkylcarbonyl, alkylcarbonylamino, aminoalkyl, aminoalkylcarbonyl, trifluoromethyl, trifluoromethylalkyl, trifluoromethylalkylaminoalkyl, amino, mono- or dialkylamino, N-hydroxyacetamido, aryl, heteroaryl, carboxyalkyl, nitrile, NR⁷SO₂R⁸, C(O)NR⁷R⁸, NR⁷C(O)R⁸, C(O)OR⁷, C(O)NR⁷SO₂R⁸, (CH₂)_mS(O)_nR⁷, (CH₂)_m-heteroaryl, O(CH₂)_m-heteroaryl, (CH₂)_mC(O)NR⁷R⁸, O(CH₂)_mC(O)OR⁷, (CH₂)_mSO₂NR⁷R⁸, and C(O)R⁷;

R³ is, C₁-C₈ alkoxy, C₃-C₇ cycloalkyl, or C₃-C₇-heterocyclyl;

R⁵ and R⁶ independently are hydrogen, C₁-C₈ alkyl, C₂-C₈ alkenyl, C₂-C₈ alkynyl, arylalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, or heteroarylalkyl; or

R⁵ and R^6, when attached to the same nitrogen atom, taken together with the nitrogen to which they are attached, form a heterocyclic ring containing from 3-8 ring members, up to four of which members can optionally be replaced with heteroatoms independently selected from oxygen, sulfur, S(O), S(O)₂, and nitrogen, provided, however, that there is at least one carbon atom in the heterocyclic ring and that if there are two or more ring oxygen atoms, the ring oxygen atoms are not adjacent to one another, wherein the heterocyclic group is unsubstituted or substituted with one, two or three groups independently selected from halogen, hydroxy, hydroxyalkyl, lower alkyl, lower alkoxy, alkoxycarbonyl, alkylcarbonyl, alkylcarbonylamino, aminoalkyl, aminoalkylcarbonyl, trifluoromethyl, trifluoromethylalkyl, trifluoromethylalkylaminoalkyl, amino, nitrile, mono- or dialkylamino, N-hydroxyacetamido, aryl, heteroaryl, carboxyalkyl, NR⁷SO₂R⁸, C(O)NR⁷R⁸, NR⁷C(O)R⁸, C(O)OR⁷, C(O)NR⁷SO₂R⁸, (CH₂)_mS(O)_nR⁷, (CH₂)_m-heteroaryl, O(CH₂)_m-heteroaryl, (CH₂)_mC(O)NR⁷R⁸, O(CH₂)_mC(O)OR⁷, and (CH₂)SO₂NR⁷R⁸;

R⁷ and R⁸ are, independently, hydrogen, C₁-C₈ alkyl, C₂-C₈ alkenyl, C₂-C₈ alkynyl, arylalkyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, or heterarylalkyl; or

R⁷ and R⁸, when attached to the same nitrogen atom, taken together with the nitrogen to which they are attached, may form a heterocyclic ring containing from 3-8 ring members, up to four of which members are optionally heteroatoms independently selected from oxygen, sulfur, S(O), S(O)₂, and nitrogen, provided, however, that there is at least one carbon atom in the heterocyclic ring and that if there are two or more ring oxygen atoms, the ring oxygen atoms are not adjacent to one another, wherein the heterocyclic group is unsubstituted or substituted with one, two or three groups independently selected from halogen, hydroxy, hydroxyalkyl, lower alkyl, lower alkoxy, alkoxycarbonyl, alkylcarbonyl, alkylcarbonylamino, aminoalkyl, aminoalkylcarbonyl, trifluoromethyl, trifluoromethylalkyl, trifluoromethylalkylaminoalkyl, amino, nitrile, mono- or dialkylamino, N-hydroxyacetamido, aryl, heteroaryl, carboxyalkyl.