Quinone-masked probes as labeling reagents for cell uptake measurements

A compound of formula (I), or a salt thereof,

• wherein
• A is a reporter moiety;
• R14 is H, alkyl, hydroxyalkyl, alkoxy, carboxyalkyl, or amidoalkyl;
• R9 and R10 are independently selected from alkyl;
• R11, R12 and R13 are independently selected from alkyl;
• X is O;
• L is —(CH2)mC(R17)2(CH2)n—Y—C(O)—;
• R17 is independently H, alkyl or both R17 together can form an alkyl ring having from 3-7 carbons;
• m is an integer from 0-2;
• n is an integer from 0-2;
• Y is O or NR15;
• R5 is -alkyl-amide, wherein the -alkyl-amide is -alkyl-CON(R32)(R33) or -alkyl-(CO)—NR34—(CRaRb)p—NR35(CO)-T, wherein
• R32 and R33 are each independently selected from hydrogen, alkyl, carboxy, aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heterocycle, alkene, polyol, alkenylpolylol, a peptide, a drug, a derivative of a drug, a biologically active moiety, and a dye;
• R34 and R35 are each independently selected from hydrogen, and alkyl;
• Ra and Rb are each independently selected from hydrogen, alkyl, and carboxy;
• p is 0 to 6;
• and
• T is selected from aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, enzyme substrate, drug, derivative of a drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof;
• or
• R15 is polyalkoxyalkyl, wherein the polyalkoxyalkyl is —(C2-C6-alkoxy)x-alkyl-CON(R32)(R33) or —(C2-C6-alkoxy)x-alkyl-(CO)—NR34-(CRaRb)p—NR35(CO)-T;
• x is an integer selected from 1 to 20;
• R32 and R33 are each independently selected from hydrogen, alkyl, carboxy, aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, enzyme substrate, drug, derivative of a drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof;
• R34 and R35 are each independently selected from hydrogen, and alkyl;
• Ra and Rb are each independently selected from hydrogen, alkyl, and carboxy;
• p is 0 to 6;
• and
• T is selected from aryl, arylalkyl, cycloalkylalkyl, heteroaryl, heteroarylalkyl, heterocycle, hydroxyalkyl, protein, polypeptide, polypeptide-based toxin, amino acid, nucleotide, polynucleotide, lipid, sugar, carbohydrate, enzyme substrate, drug, derivative of a drug, polymer-linked nanoparticle, antibody, detergent, and a dye, or a combination thereof;
• or
• R15 is
• wherein
• R40 is selected from the group consisting of hydrogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclyl, and cycloalkyl, wherein said aryl, heteroaryl, heterocyclyl, and cycloalkyl are unsubstituted or substituted with one or more suitable substituents;
• and
• x is an integer selected from 1 to 20.