Abstract: There is provided compounds of formula (I), wherein R1, R2, X1, X2, and X3 have meanings given in the description, and pharmaceutically-acceptable salts thereof, which compounds are useful as positron emission tomography (PET) imaging agents, useful in the treatment of diseases in which inhibition of epidermal growth factor receptor tyrosine kinase activity or the inhibition of HER2 activity is desired and/or required, and useful in the treatment of cancer.

Abstract: A method for preparing a conjugated molecule comprising a first monomer coupled to a second monomer, said method comprising: (i) linking the first monomer to a solid support via the germanium atom of a germyl linking group; (ii) coupling the first monomer to the second monomer in a coupling position to form a bound conjugated molecule, wherein the second monomer has a protecting group in a non-coupling position; (iii) optionally sequentially coupling a third, fourth . . . and nth monomer to the second, third and (n?1)th monomer respectively; (iv) removing the protecting group; and (v) ipso-degermylation to release the bound conjugated molecule.