Commercially available reagent grade solvents and chemicals were used without further purification. Anhydrous solvents were acquired from solvent towers within the department and stored over 3 Å molecular sieves. 1 H, 13 C, COSY, TOCSY, HSQC, HMBC NMR spectra were recorded on a Bruker AVIII 400 or 700 spectrometer. Chemical shifts are reported in ppm and referenced to residual protonated impurities in the solvent for NMR spectra. High Resolution Electrospray Mass Spectrometry was carried out by Dr Lisa Haigh of the mass spectrometry service at Imperial College, or independently on an Agilent 6200 TOF LC-MS instrument. LC-MS for K222-PSMA was measured on a Waters 3100 Mass Detector equipped with a Waters 2998 Photodiode Array Detector, Waters 515 HPLC Pump, Waters 2545 Quarternary Gradient Module, and a Waters 2767 Sample Manager. LC-MS solvents were Millipore water and acetonitrile (with 0.1% formic acid). A 18 min gradient was run from 5% to 100% Acetonitrile on a XBridge BEH C18 Column, 130Å, 5 µm, 4.6 mm X 100 mm. Flash chromatography used silica gel (60 Å pore size). Where specified, automated flash chromatography was performed using a Biotage Isolera Four unit and 10 g or 25 g SNAP KP-Sil/Sfar duo cartridge. HPLC was performed on an Agilent 1200 Series Liquid Chromatograph with UV and LabLogic Flow-Count detector with a sodium-iodide probe (B-FC-3200). Unless otherwise mentioned the mobile phase A contained H2O with 0.1% FA, and mobile phase B contained MeCN with 0.1% FA.