Radical compounds and methods of using thereof
Disclosed are methods for performing dynamic nuclear polarization using the polarizing agents described herein. In general, the methods involve (a) providing a frozen sample in a magnetic field, wherein the frozen sample includes a polarizing agent described herein and an analyte with at least one spin half nucleus; (b) polarizing the at least one spin half nucleus of the analyte by irradiating the frozen sample with radiation having a frequency that excites electron spin transitions in the polarizing agent; (c) optionally melting the sample to produce a molten sample; and (d) detecting nuclear spin transitions in the at least one spin half nucleus of the analyte in the frozen or molten sample. In certain embodiments, the polarizing agents can be peptide-based. In these embodiments, the polarizing agents can be readily prepared by solid-phase peptide synthesis.
1. A compound defined by Formula I
wherein
L represents a direct bond or one amino acid residue;
R 1 is selected from the group consisting of hydrogen, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, C 1-12 alkylcarbonyl, C 1-12 alkoxycarbonyl, C 1-12 alkylcarbamyl, di(C 1-12 -alkyl)carbamyl, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 2 is selected from the group consisting of hydrogen, hydroxy, —OR 11 , C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, amino, C 1-12 alkylamino; di(C 1-12 -alkyl)amino, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 3 and R 4 are independently selected from group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; or R 3 and R 4 , together with the carbon atom to which they are attached, form a 3-10 membered cycloalkyl or 4-10 membered heterocycloalkyl ring each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 5 and R 6 are independently selected from group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; or R 5 and R 6 , together with the carbon atom to which they are attached, form a 3-10 membered cycloalkyl or 4-10 membered heterocycloalkyl ring each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 7 and R 8 are independently selected from group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; or R 7 and R 8 , together with the carbon atom to which they are attached, form a 3-10 membered cycloalkyl or 4-10 membered heterocycloalkyl ring each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 9 and R 10 are independently selected from group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; or R 9 and R 10 , together with the carbon atom to which they are attached, form a 3-10 membered cycloalkyl or 4-10 membered heterocycloalkyl ring each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 11 is selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; and
each R X , when present, are each independently selected from OH, NO 2 , CN, halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-4 haloalkyl, C 1-6 alkoxy, C 1-6 haloalkoxy, cyano-C 1-3 alkyl, HO-C 1-3 alkyl, amino, C 1-6 alkylamino, di(C 1-6 alkyl)amino, thio, C 1-6 alkylthio, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, carbamyl, C 1-6 alkylcarbamyl, di(C 1-6 alkyl)carbamyl, carboxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 alkylcarbonylamino, C 1-6 alkylsulfonylamino, aminosulfonyl, C 1-6 alkylaminosulfonyl, di(C 1-6 alkyl)aminosulfonyl, aminosulfonylamino, C 1-6 alkylaminosulfonylamino, di(C 1-6 alkyl)aminosulfonylamino, aminocarbonylamino, C 1-6 alkylaminocarbonylamino, and di(C 1-6 alkyl)aminocarbonylamino;
wherein when R 1 and R 2 are poly(amino acid), the poly(amino acid) group comprises from 2 to 4 amino acid residues;
wherein when L is a direct bond, R 1 is not hydrogen and R 2 is not hydroxy; and
wherein when one or more of L, R 1 , and R 2 comprise an amino acid residue, at least one of these amino acid residues is not alanine.
2. The compound of claim 1 , wherein the compound is defined by Formula IA
wherein
L represents a direct bond or one amino acid residue;
R 1 is selected from the group consisting of hydrogen, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, C 1-12 alkylcarbonyl, C 1-12 alkoxycarbonyl, C 1-12 alkylcarbamyl, di(C 1-12 -alkyl)carbamyl, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 2 is selected from the group consisting of hydrogen, hydroxy, —OR 11 , C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, amino, C 1-12 alkylamino; di(C 1-12 -alkyl)amino, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 11 is selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; and
each R X , when present, are each independently selected from OH, NO 2 , CN, halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-4 haloalkyl, C 1-6 alkoxy, C 1-6 haloalkoxy, cyano-C 1-3 alkyl, HO-C 1-3 alkyl, amino, C 1-6 alkylamino, di(C 1-6 alkyl)amino, thio, C 1-6 alkylthio, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, carbamyl, C 1-6 alkylcarbamyl, di(C 1-6 alkyl)carbamyl, carboxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 alkylcarbonylamino, C 1-6 alkylsulfonylamino, aminosulfonyl, C 1-6 alkylaminosulfonyl, di(C 1-6 alkyl)aminosulfonyl, aminosulfonylamino, C 1-6 alkylaminosulfonylamino, di(C 1-6 alkyl)aminosulfonylamino, aminocarbonylamino, C 1-6 alkylaminocarbonylamino, and di(C 1-6 alkyl)aminocarbonylamino;
wherein when R 1 and R 2 are poly(amino acid), the poly(amino acid) group comprises from 2 to 4 amino acid residues;
wherein when L is a direct bond, R 1 is not hydrogen and R 2 is not hydroxy; and
wherein when one or more of L, R 1 , and R 2 comprise an amino acid residue, at least one of these amino acid residues is not alanine.
3. The compound of claim 1 , wherein the compound is defined by Formula IB
wherein
L represents a direct bond or one amino acid residue;
R 1 is selected from the group consisting of hydrogen, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, C 1-12 alkylcarbonyl, C 1-12 alkoxycarbonyl, C 1-12 alkylcarbamyl, di(C 1-12 -alkyl)carbamyl, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 2 is selected from the group consisting of hydrogen, hydroxy, —OR 11 , C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, amino, C 1-12 alkylamino; di(C 1-12 -alkyl)amino, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 11 is selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups; and
each R X , when present, are each independently selected from OH, NO 2 , CN, halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-4 haloalkyl, C 1-6 alkoxy, C 1-6 haloalkoxy, cyano-C 1-3 alkyl, HO—C 1-3 alkyl, amino, C 1-6 alkylamino, di(C 1-6 alkyl)amino, thio, C 1-6 alkylthio, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, carbamyl, C 1-6 alkylcarbamyl, di(C 1-6 alkyl)carbamyl, carboxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 alkylcarbonylamino, C 1-6 alkylsulfonylamino, aminosulfonyl, C 1-6 alkylaminosulfonyl, di(C 1-6 alkyl)aminosulfonyl, aminosulfonylamino, C 1-6 alkylaminosulfonylamino, di(C 1-6 alkyl)aminosulfonylamino, aminocarbonylamino, C 1-6 alkylaminocarbonylamino, and di(C 1-6 alkyl)aminocarbonylamino.
4. The compound of claim 1 , wherein the compound is defined by Formula IC
wherein
L represents a direct bond or one amino acid residue;
R 1 is selected from the group consisting of hydrogen, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, C 1-12 alkylcarbonyl, C 1-12 alkoxycarbonyl, C 1-12 alkylcarbamyl, di(C 1-12 -alkyl)carbamyl, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 2 is selected from the group consisting of hydrogen, hydroxy, —OR 11 , C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, amino, C 1-12 alkylamino; di(C 1-12 -alkyl)amino, amino acid, poly(amino acid), and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 11 is selected from the group consisting of C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, and poly(alkylene oxide), each optionally substituted with 1, 2, 3, or 4 independently selected R X groups;
R 12 is selected from the group consisting of OH, NO 2 , CN, halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-4 haloalkyl, C 1-6 alkoxy, C 1-6 haloalkoxy, cyano-C 1-3 alkyl, HO—C 1-3 alkyl, amino, C 1-6 alkylamino, di(C 1-6 alkyl)amino, thio, C 1-6 alkylthio, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, carbamyl, C 1-6 alkylcarbamyl, di(C 1-6 alkyl)carbamyl, carboxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 alkylcarbonylamino, C 1-6 alkylsulfonylamino, aminosulfonyl, C 1-6 alkylaminosulfonyl, di(C 1-6 alkyl)aminosulfonyl, aminosulfonylamino, C 1-6 alkylaminosulfonylamino, di(C 1-6 alkyl)aminosulfonylamino, aminocarbonylamino, C 1-6 alkylaminocarbonylamino, di(C 1-6 alkyl)aminocarbonylamino, C 3-10 cycloalkyl, 6-10 membered aryl, 5-10 membered heteroaryl, 4-10 membered heterocycloalkyl, C 3-10 cycloalkyl-C 1-4 alkylene, 4-10 membered heterocycloalkyl-C 1-4 alkylene, 6-10 membered aryl-C 1-4 alkylene, 5-10 membered heteroaryl-C 1-4 alkylene, and poly(alkylene oxide); and
each R X , when present, are each independently selected from OH, NO 2 , CN, halo, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, C 1-4 haloalkyl, C 1-6 alkoxy, C 1-6 haloalkoxy, cyano-C 1-3 alkyl, HO—C 1-3 alkyl, amino, C 1-6 alkylamino, di(C 1-6 alkyl)amino, thio, C 1-6 alkylthio, C 1-6 alkylsulfinyl, C 1-6 alkylsulfonyl, carbamyl, C 1-6 alkylcarbamyl, di(C 1-6 alkyl)carbamyl, carboxy, C 1-6 alkylcarbonyl, C 1-6 alkoxycarbonyl, C 1-6 alkylcarbonylamino, C 1-6 alkylsulfonylamino, aminosulfonyl, C 1-6 alkylaminosulfonyl, di(C 1-6 alkyl)aminosulfonyl, aminosulfonylamino, C 1-6 alkylaminosulfonylamino, di(C 1-6 alkyl)aminosulfonylamino, aminocarbonylamino, C 1-6 alkylaminocarbonylamino, and di(C 1-6 alkyl)aminocarbonylamino.
5. The compound of claim 1 , wherein L represents a direct bond.
6. The compound of claim 1 , wherein L comprises one amino acid residue.
7. The compound of claim 6 , wherein L is defined by the structure below
wherein for each occurrence in L, R 14 is H and R 13 is selected from one of the following
or R 13 and R 14 , together with the atoms to which they are attached, form a five-membered heterocycle defined by the structure below
m is 1.
8. The compound of claim 6 , wherein L comprises a serine residue or a threonine residue.
9. The compound of claim 6 , wherein L comprises a 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid residue.
10. The compound of claim 6 , wherein L comprises an asparagine residue.
11. The compound of claim 6 , wherein L comprises a glutamine residue.
12. The compound of claim 6 , wherein L comprises an aspartic acid residue or a glutamic acid residue.
13. The compound of claim 6 , wherein L comprises a cysteine residue.
14. The compound of claim 1 , wherein L comprises from 3 to 20 atoms.
15. The compound of claim 1 , wherein R 1 is H.
16. The compound of claim 1 , wherein R 1 comprises an amino acid residue.
17. The compound of claim 16 , wherein the amino acid residue is selected from the group consisting of a serine residue, a threonine residue, an asparagine residue, a glutamine residue, an aspartic acid residue, a cysteine residue, a 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid residue, and a glutamic acid residue.
18. The compound of claim 1 , wherein R 1 comprises an acetyl group.
19. The compound of claim 1 , wherein R 2 comprises a hydroxy group.
20. The compound of claim 1 , wherein R 2 comprises an amino acid residue.
21. The compound of claim 20 , wherein the amino acid residue is selected from the group consisting of a serine residue, a threonine residue, an asparagine residue, a glutamine residue, an aspartic acid residue, a cysteine residue, a 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid residue, and a glutamic acid residue.
22. The compound of claim 1 , wherein the compound is
23. The compound of claim 1 , wherein when one or more of L, R 1 , ad R 2 comprise an amino acid residue selected from the group consisting of a serine residue, a threonine residue, an asparagine residue, a glutamine residue, an aspartic acid residue, a cysteine residue, a 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid residue, and a glutamic acid residue.