Bivalent linkers and conjugates thereof
Bivalent linkers derived from compounds of formulae (V), (VI), and (VII), where X 1 and X 2 are leaving groups and the other variables are as defined in the claims, to be included in or for preparing vitamin, drug, diagnostic agent, and/or imaging agent conjugates are described.
1. A compound of the formula
wherein
X 1 is a leaving group displaceable by a nucleophile;
Q is
where R a and R b are each independently selected from the group consisting of hydrogen and alkyl; or R a and R b are taken together with the attached carbon atom to form a carbocyclic ring; n is an integer from 1 to about 4; and * represents the point of attachment; and
X 2 is optionally substituted heteroaryloxy.
2. The compound of claim 1 wherein n is 1.
3. The compound of claim 1 wherein R a and R b are selected from the group consisting of hydrogen and lower alkyl.
4. The compound of claim 1 wherein R a and R b are each hydrogen.
5. The compound of claim 1 wherein R a and R b are taken together with the attached carbon atom to form a carbocyclic ring.
6. The compound of claim 1 wherein R a and R b are taken together with the attached carbon atom to form cyclopropyl.
7. The compound of claim 1 wherein the X 1 is optionally substituted heteroarylthio.
8. The compound of claim 1 wherein the X 2 is optionally substituted benzotriazolyloxy.