R¹ represents a hydrogen atom or a halogen;

R² represents a hydrogen atom or a halogen;

R³ represents a hydrogen atom, an optionally substituted C1-C8 alkyl group, an optionally substituted C3-C8 cycloalkyl group, an optionally substituted heterocyclic group, an optionally substituted C6-C14 aryl group or —OR⁵;

R⁵ represents a hydrogen atom, an optionally substituted C1-C8 alkyl group or —(C═O)R⁶;

R⁶ represents an optionally substituted C1-C8 alkyl group;

n represents 0 or 1, or n represents 0 when R³ is —OR⁵;

R⁴ represents a hydrogen atom, an optionally substituted C1-C8 alkyl group, an optionally substituted C2-C8 alkenyl, an optionally substituted C2-C8 alkynyl, an optionally substituted C3-C8 cycloalkyl group, an optionally substituted C6-C14 aryl group, an optionally substituted heterocyclic group, an optionally substituted heterocyclylalkyl group or an optionally substituted C7-C16 aralkyl group; the substituents in the optionally substituted C6-C14 aryl group as are one or more substituents selected from the group consisting of halogen, —CN, —NO₂, —CHO, —OH, —COOH, optionally substituted C1-C8 alkyl group, optionally substituted C2-C8 alkenyl, optionally substituted C2-C8 alkynyl, optionally substituted C3-C8 cycloalkyl group, —O—(CH₂)_m—W, optionally substituted C6-C14 aryl group, optionally substituted heterocyclic group, —C(═O)—R¹³³, —O—C(═O)R²⁶, —C(═O)OR²⁷, —NR²⁸C(═O)R²⁹, —NR³⁰R³¹, —C(═O)NR³²R³³, —NR³⁴C(═X¹)OR³⁵, —NR³⁶C(═X²)NR³⁷R³⁸, —NR³⁹—SO₂R⁴⁰, —S(O)_r—R⁴¹ and —SO₂NR⁴²R⁴³, wherein X¹ or X² represents O, S, N—CN or NH and r represents 0 to 2;

W represents a hydrogen atom, an optionally substituted C1-C8 alkyl group, an optionally substituted C2-C8 alkenyl, an optionally substituted C2-C8 alkynyl, an optionally substituted C3-C8 cycloalkyl group, an optionally substituted C6-C14 aryl group or an optionally substituted heterocyclic group, and in this case m represents 0 to 4; or W represents an optionally substituted C1-C8 alkoxy group, —NR¹⁵⁰R¹⁵¹ or an optionally substituted phenoxy group and in this case m represents 1 to 4;

R²⁶ to R⁴³, R¹³³, R¹⁵⁰ and R¹⁵¹ may be identical or different and each represents a hydrogen atom, an optionally substituted C1-C8 alkyl group, an optionally substituted C2-C8 alkenyl, an optionally substituted C2-C8 alkynyl, an optionally substituted C3-C8 cycloalkyl group, an optionally substituted C6-C14 aryl group, an optionally substituted heterocyclic group, an optionally substituted aralkyl group or an optionally substituted heterocyclylalkyl group, or, when R³⁰ and R³¹, R³² and R³³, R³⁷ and R³⁸, R⁴² and R⁴³ or R¹⁵⁰ and R¹⁵¹ are optionally substituted C1-C8 alkyl groups, the substituents in each combination may form a saturated or unsaturated 5- to 7-membered ring together with the nitrogen atom to which they bond, and this ring may contain 1 or 2 heteroatoms selected from the group consisting of oxygen atom, nitrogen atom and sulfur atom besides the nitrogen atom to which these substituents bond;

-A-B- represents —CH₂—CH(-Z¹)-, —(CH₂)_p—, —CH═C(-Z²)- or —(CH₂)_q—C(═O)—;

p represents 3 and q represents 1 or 2;

Z¹ and Z² may be identical or different and each represents a hydrogen atom or —CH₂—OR¹¹; and

R¹¹ represents a hydrogen atom, an optionally substituted C1-C8 alkyl group or a substituted silyl group.