Imidazopyrazine derivatives, process for preparation thereof, and their uses as luciferins

A method to detect, and/or measure the enzymatic activity of, a luminogenic protein, in vitro, in cellulo, ex vivo or in vivo, comprising a step of contacting a compound of following formula (I) with a solution comprising a strong acid;

• wherein:
• R1 represents H or a group selected from C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups, said C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y1 group;
• R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups, said C6-C10 aryl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y2 group;
• or R1 and R2 together form with the two carbon atom to which they are respectively attached a C5-C7 cycloalkene group, a C4-C7 heterocycloalkene group, or a C6-C10 arene, said C5-C7 cycloalkene group and C4-C7 heterocycloalkene groups being fused with a C6-C10 arene, said C5-C7 cycloalkene group, C4-C7 heterocycloalkene group, C6-C10 arene, C5-C7 cycloalkene group and C4-C7 heterocycloalkene groups being optionally substituted by at least one Y12 group;
• R3 represents H, a C1-C6 alkyl, an aralkyl group, a hetaralkyl group or a heterocycloalkyl-CH2— group, said C1-C6 alkyl, aralkyl group, hetaralkyl group and heterocycloalkyl-CH2— group being optionally substituted by at least one Y3 group;
• R4 represents H or a group selected from C1-C6 alkyl and C3-C7 cycloalkyl groups, said C1-C6 alkyl and C3-C7 cycloalkyl groups being optionally substituted by at least one Y4 group;
• R5 represents a —C(═O)Ra group or a —C(═O)ORa group, said C(═O)Ra group and —C(═O)ORa group being optionally substituted by at least one Y5 group;
• Ra represents H, a C1-C6 alkyl group, a C3-C7 cycloalkyl group, a C6-C10 aryl, or an aralkyl group, said C1-C6 alkyl group, C3-C7 cycloalkyl group, C6-C10 aryl, and aralkyl group being optionally substituted by at least one Ya group;
• Z represents a C6-C10 aryl, a C5-C10-membered heteroaryl groups, a C1-C6 alkyl, a C3-C7 cycloalkyl, a C4-C7 heterocycloalkyl, said C6-C10 aryl, C5-C10-membered heteroaryl groups, C1-C6 alkyl, C3-C7 cycloalkyl and C4-C7 heterocycloalkyl being optionally substituted by at least one YZ group;
• said Y1, Y2, Y12, Y3, Y4, Y5, Ya and YZ groups being each independently selected from:
• a C1-C6 alkyl;
• a C3-C7 cycloalkyl;
• a C6-C10 aryl;
• a C5-C10-membered heteroaryl group;
• an halogen;
• a —CF3 group;
• a —CN group;
• a —ORi group;
• a —OSO3H group;
• a —NRiRii group;
• a guanidinyl group;
• a —C(═O)ORa group, Ra being as defined above;
• Ri and Rii each independently represent H, a C1-C6 alkyl group, a C3-C10 cycloalkyl group, an aralkyl group or an ad hoc protective group;
• or together form with the nitrogen atom to which they are attached a C4-C7 heterocycloalkyl group.

A compound of following formula (III):

• wherein:
• R1 represents H or a group selected from C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups, said C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y1 group;
• R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups, said C6-C10 aryl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y2 group;
• R3 represents an aralkyl group, said aralkyl group being optionally substituted by at least one Y3 group;
• R4 represents H or a group selected from C1-C6 alkyl and C3-C7 cycloalkyl groups, said C1-C6 alkyl and C3-C7 cycloalkyl groups being optionally substituted by at least one Y4 group;
• Z represents a group of following formula:
• or an oxazolyl, or an oxadiazolyl;
• R, R′, R″ and R′″ each independently represent H or a group selected from:
• a C1-C6 alkyl group;
• a C3-C7 cycloalkyl group;
• an halogen;
• a —ORi group;
• a —CF3 group;
• X represents O or S;
• said Y1, Y2, Y3 and Y4, groups being each independently selected from:
• a C1-C6 alkyl group;
• a C3-C7 cycloalkyl group;
• an halogen;
• a —ORii group;
• Ri and Rii each independently represent H, a C1-C6 alkyl group, a C3-C10 cycloalkyl group or an aralkyl group;
• provided that:
• when Z=Z1:
• at least one of R, R′ and R″ does not represent H;
• or
• when R, R′ and R″ represent H, then R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least an halogen group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group;
• when Z=Z2:
• at least one of R, R′, R″ and R′″ does not represent H;
• or
• when R, R′, R″ and R′″ represent H;
• then R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least a halogen group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group;
• or
• when R, R′ and R′″ represent H and R″ represents a C1-C6 alkyl group or a —ORi group;
• then R2 does not represent a 4-HO-Ph- group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group.

A method of preparation of a compound of a compound of following formula (III):

• wherein:
• R1 represents H or a group selected from C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups, said C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y1 group;
• R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups, said C6-C10 aryl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y2 group;
• R3 represents an aralkyl group, said aralkyl group being optionally substituted by at least one Y3 group;
• R4 represents H or a group selected from C1-C6 alkyl and C3-C7 cycloalkyl groups, said C1-C6 alkyl and C3-C7 cycloalkyl groups being optionally substituted by at least one Y4 group;
• Z represents a group of following formula:
• or an oxazolyl, or an oxadiazolyl;
• R, R′, R″ and R′″ each independently represent H or a group selected from:
• a C1-C6 alkyl group;
• a C3-C7 cycloalkyl group;
• an halogen;
• a —ORi group;
• a —CF3 group;
• X represents O or S;
• said Y1, Y2, Y3 and Y4, groups being each independently selected from:
• a C1-C6 alkyl group;
• a C3-C7 cycloalkyl group;
• an halogen;
• a —ORii group;
• Ri and Rii each independently represent H, a C1-C6 alkyl group, a C3-C10 cycloalkyl group or an aralkyl group;
• provided that:
• when Z=Z1:
• at least one of R, R′ and R″ does not represent H;
• or
• when R, R′ and R″ represent H, then R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least an halogen group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group;
• when Z=Z2:
• at least one of R, R′, R″ and R′″ does not represent H;
• or
• when R, R′, R″ and R′″ represent H;
• then R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least a halogen group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group;
• or
• when R, R′ and R′″ represent H and R″ represents a C1-C6 alkyl group or a —ORi group;
• then R2 does not represent a 4-HO-Ph- group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group, comprising a step of conversion of a compound of formula (IV) as defined as follows into a compound of formula (III):
• wherein:
• R1 represents H or a group selected from C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups, said C1-C6 alkyl, C3-C7 cycloalkyl, C6-C10 aryl, aralkyl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y1 group;
• R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups, said C6-C10 aryl and C5-C10-membered heteroaryl groups being optionally substituted by at least one Y2 group;
• R3 represents an aralkyl group, said aralkyl group being optionally substituted by at least one Y3 group;
• R4 represents H or a group selected from C1-C6 alkyl and C3-C7 cycloalkyl groups, said C1-C6 alkyl and C3-C7 cycloalkyl groups being optionally substituted by at least one Y4 group;
• Z represents a group of following formula:
• or an oxazolyl, or an oxadiazolyl;
• R, R′, R″ and R′″ each independently represent H or a group selected from:
• a C1-C6 alkyl group;
• a C3-C7 cycloalkyl group;
• an halogen;
• a —ORi group;
• a —CF3 group;
• X represents O or S;
• said Y1, Y2, Y3 and Y4, groups being each independently selected from:
• a C1-C6 alkyl group;
• a C3-C7 cycloalkyl group;
• an halogen;
• a —ORii group;
• Ri and Rii each independently represent H, a C1-C6 alkyl group, a C3-C10 cycloalkyl group or an aralkyl group;
• provided that:
• when Z=Z1:
• at least one of R, R′ and R″ does not represent H;
• or
• when R, R′ and R″ represent H, then R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least an halogen group, in particular —F, R2 representing in particular a 2-F-phenyl, a 3-F-phenyl, or a 2,6-diF-phenyl group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group, in particular —F;
• when Z=Z2:
• at least one of R, R′, R″ and R′″ does not represent H;
• or
• when R, R′, R″ and R′″ represent H;
• then R2 represents a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least a halogen group, in particular —F, R2 representing in particular 2-F-phenyl, a 3-F-phenyl, or a 2,6-diF-phenyl group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group, in particular —F;
• or
• when R, R′ and R′″ represent H and R″ represents a C1-C6 alkyl group or a —ORi group;
• then R2 does not represent a 4-HO-Ph- group, R2 representing in particular a phenyl group or a group selected from C6-C10 aryl and C5-C10-membered heteroaryl groups substituted by at least a halogen group, in particular —F, R2 representing more particularly a 2-F-phenyl, a 3-F-phenyl, or a 2,6-diF-phenyl group;
• or R3 represents a group selected from C6-C10 aralkyl groups substituted by at least an halogen group, in particular —F,
• R5 represents a —C(═O)Ra group or a —C(═O)ORa group, said C(═O)Ra group and —C(═O)ORa group being optionally substituted by at least one Y5 group, wherein Ra represents H, a C1-C6 alkyl group, a C3-C7 cycloalkyl group, a C6-C10 aryl, or an aralkyl group, said C1-C6 alkyl group, C3-C7 cycloalkyl group, C6-C10 aryl, and aralkyl group being optionally substituted by at least one Ya group.