Cage amine ligands for metallo-radiopharmaceuticals
The present invention relates to compounds that are useful as metal ligands and which can be bound to a biological entity such as a molecular recognition moiety and methods of making these compounds. Once the compounds that are bound to a biological entity are coordinated with a suitable metallic radionuclide, the coordinated compounds are useful as radiopharmaceuticals in the areas of radiotherapy and diagnostic imaging. The invention therefore also relates to methods of diagnosis and therapy utilizing the radiolabelled compounds of the invention.
1. A method of functionalizing a compound of the formula (1) or a metal complex thereof:
wherein Lig is a nitrogen containing macrocyclic metal ligand of the formula
V is selected from the group consisting of N and CR 1 ;
each R x and R y are independently selected from group consisting of H, CH 3 , and CO 2 H, NO 2 , CH 2 OH, H 2 PO 4 , HSO 3 , CN, CONH 2 and CHO;
each p is independently an integer selected from the group consisting of 2, 3, and 4;
R 1 is selected from the group consisting of H, OH, halogen, NO 2 , NH 2 , optionally substituted C 1 -C 12 alkyl, optionally substituted C 6 -C 18 aryl, cyano, CO 2 R 2 , NHR 3 and N(R 3 ) 2 ;
R 2 is selected from the group consisting of H, halogen, an oxygen protecting group, substituted C 1 -C 12 alkyl, optionally substituted C 2 -C 12 alkenyl, optionally substituted C 2 -C 12 alkynyl and optionally substituted C 2 -C 12 heteroalkyl; and
each R 3 is independently selected from the group consisting of H, a nitrogen protecting group, optionally substituted C 1 -C 12 alkyl, —(C═O)-substituted C 1 -C 12 alkyl, optionally substituted C 2 -C 12 alkenyl, optionally substituted C 2 -C 12 alkynyl and optionally substituted C 2 -C 12 heteroalkyl;
L is a group of the formula
—(CH 2 ) a —,
wherein optionally one or more of the CH 2 groups may be independently replaced by a heteroatomic group selected from S, O and NR 4 where R 4 is selected from the group consisting of H, optionally substituted C 1 -C 12 alkyl optionally substituted C 3 -C 12 cycloalkyl optionally substituted C 6 -C 18 aryl, and optionally substituted C 1 -C 18 heteroaryl;
a is an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10;
the method comprising;
(a) converting the compound of formula (1) or a metal complex thereof to a compound of formula (II) or a metal complex thereof
wherein L 1 is a spacer group of the formula
—(CH 2 ) a —,
wherein optionally one or more of the CH 2 groups may be independently replaced by a heteroatomic group selected from S, O and NR 4 where R 4 is selected from the group consisting of H, optionally substituted C 1 -C 12 alkyl, optionally substituted C 3 -C 12 cycloalkyl, optionally substituted C 6 -C 18 aryl, and optionally substituted C 1 -C 18 heteroaryl;
a is an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10;
(b) converting the compound of formula (2) or a metal complex thereof to a compound of formula (3) or a metal complex thereof
wherein R or a protected form thereof is a moiety capable of binding to a molecular recognition moiety.
2. The method according to claim 1 wherein step (a) comprises the steps of:
(a1) converting the compound of formula (1) into a compound of formula (Ia)
wherein Lv is a leaving group that can be displaced by a nitrogen moiety in a nucleophilic substitution reaction;
(a2) reacting the compound of formula (1a) with a nitrogen nucleophile of the formula:
to form a compound of formula (2).
3. The method according to claim 1 wherein the compound of formula (2) is converted to a compound of formula (3) by reacting the amine with a reagent selected from the group consisting of an azide, thiosphosgene, carbon disulphide and an acid anhydride.
4. The method according to claim 3 wherein the reagent is an azide.
5. The method according to claim 3 wherein the reagent is thiosphosgene.
6. The method according to claim 3 wherein the reagent is maleic anhydride.
7. The method according to claim 1 , wherein Lig is selected from the group consisting of:
and
wherein R 1 is as defined in claim 1 .
8. The method according to claim 1 wherein a is an integer selected from the group consisting of 1, 2, 3, 4, and 5.
9. The method according to claim 1 wherein L is selected from the group consisting of —CH 2 —, —CH 2 CH 2 —, —CH 2 CH 2 CH 2 —, —CH 2 CH 2 CH 2 CH 2 — and —CH 2 OCH 2 —.
10. The method according to claim 1 , wherein L is —CH 2 CH 2 CH 2 —.
11. The method according to claim 1 wherein a is an integer selected from the group consisting of 1, 2, 3, 4, and 5.
12. The method according to claim 1 wherein L I is selected from the group consisting of —CH 2 —, —CH 2 CH 2 —, —CH 2 CH 2 CH 2 —, and —CH 2 CH 2 CH 2 CH 2 .
13. The method according to claim 1 , wherein L 1 is —CH 2 CH 2 CH 2 .
14. The method according to claim 1 wherein R is a moiety capable of taking part in a click chemistry reaction with a complementary moiety on a molecular recognition moiety, wherein R is selected from the group consisting of —NCS, CO 2 H, NH 2 , an azide, an alkyne, an isonitrile, and a tetrazine, or a protected form thereof.
15. The method according to claim 1 , wherein the compound is in the form of a metal complex when subjected to conversion or reaction.
16. The method according to claim 15 , wherein the metal is magnesium.