Substituted coumarin dyes and uses as fluorescent labels

A compound of Formula (II) or (II′), or a salt or mesomeric form thereof:

• wherein X is S, O, or NRa;
• Y is O or NH;
• each R1, R2, R3 and R5 is independently H, optionally substituted C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, C1-C6 haloalkyl, C1-C6 haloalkoxy, C1-C6 hydroxyalkyl, (C1-C6 alkoxy)(C1-C6 alkyl), optionally substituted amino, halo, cyano, hydroxy, nitro, sulfonyl, sulfino, sulfo, sulfonate, S-sulfonamido, N-sulfonamido, optionally substituted C3-C10 carbocyclyl, optionally substituted C6-C10 aryl, optionally substituted 5 to 10 membered heteroaryl, or optionally substituted 3 to 10 membered heterocyclyl;
• R4 is —NRbRc, halo, —ORd or —OS(O)2Rd;
• each of R6 and R7 is independently H, carboxyl, —C(O)NRbRc, —C(O)ORd, C1-C6 alkyl, substituted C1-C6 alkyl, C1-C6 haloalkyl, halo, optionally substituted amino, N-sulfonamido, sulfonyl, S-sulfonamido, hydroxy, cyano, nitro, optionally substituted phenyl, optionally substituted C3-C8 carbocyclyl, optionally substituted 5 to 10 membered heteroaryl, or optionally substituted 3 to 10 membered heterocyclyl;
• or R6 and R7 in Formula (II) together with the atoms to which they are attached form an optionally substituted C5-C8 carbocyclyl or an optionally substituted 5 to 8 membered heterocyclyl;
• Ra is H or C1-C6 alkyl;
• each Rb and Rc is independently H, C1-C6 alkyl, or substituted C1-C6 alkyl;
• or Rb and Rc together with the nitrogen atom to which they are attached form an optionally substituted 4 to 10 membered heterocyclyl;
• and
• each Rd is independently optionally substituted C1-C6 alkyl or optionally substituted phenyl;
• provided that
• at least one of R6 and R7, or the optionally substituted C5-C8 carbocyclyl or optionally substituted 5 to 8 membered heterocyclyl formed from R6 and R7 and the atoms to which they are attach, comprises a carboxyl;
• or
• R4 is —NRbRc and at least one of Rb and Rc comprises a carboxyl or —C(O)ORd.

A process of preparing a compound of Formula (IIa) or (IIa′), comprising reacting a compound of Formula (III) or (III′) with an amine of formula NHRb respectively;

• wherein X is S, O, or NRa;
• Y is O or NH;
• each R1, R2, R3 and R5 is independently H, optionally substituted C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkenyl, C2-C6 alkynyl, C1-C6 haloalkyl, C1-C6 haloalkoxy, C1-C6 hydroxyalkyl, (C1-C6 alkoxy)(C1-C6 alkyl), optionally substituted amino, halo, cyano, hydroxy, nitro, sulfonyl, sulfino, sulfo, sulfonate, S-sulfonamido, N-sulfonamido, optionally substituted C3-C10 carbocyclyl, optionally substituted C6-C10 aryl, optionally substituted 5 to 10 membered heteroaryl, or optionally substituted 3 to 10 membered heterocyclyl;
• each of R6 and R7 is independently H, carboxyl, —C(O)NRbRc, —C(O)ORd, C1-C6 alkyl, substituted C1-C6 alkyl, C1-C6 haloalkyl, halo, optionally substituted amino, N-sulfonamido, sulfonyl, S-sulfonamido, hydroxy, cyano, nitro, optionally substituted phenyl, optionally substituted C3-C8 carbocyclyl, optionally substituted 5 to 10 membered heteroaryl, or optionally substituted 3 to 10 membered heterocyclyl;
• or R6 and R7 in Formula (III) together with the atoms to which they are attached form an optionally substituted C5-C8 carbocyclyl or an optionally substituted 5 to 8 membered heterocyclyl;
• Rx is halo, —ORd or —OS(O)2Rd;
• Ra is H or C1-C6 alkyl;
• each Rb and Rc is independently H, C1-C6 alkyl, or substituted C1-C6 alkyl;
• or Rb and Rc together with the nitrogen atom to which they are attached form an optionally substituted 4 to 10 membered heterocyclyl;
• and
• each Rd is independently optionally substituted C1-C6 alkyl or optionally substituted phenyl.