Scheme 1. Synthesis of PROTACs 6a–6j.
Reagents and conditions: (a) 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo [4,5-b]-pyridinium 3-oxide hexafluorophosphate (HATU), N,N-diisopropylethylamine (DIPEA), N,N-dimethylformamide (DMF), room temperature (rt), 39–71%; (b) trifluoroacetic acid (TFA), dichloromethane (DCM), rt.