Synthesis of benzophenone-functionalized tag-free probes 10a–b.a
aReagents and conditions. a) LDA, 1h; then ethyl 3,3-dimethyl acrylate, ZnI2, diglyme, −78°C – RT, 2h, 50%; b) (Bu3Sn)2, Pd(PPh3)4, toluene, reflux, 16h, 37%; c) 1 atm CO, PdCl2(PPh3)2, iodobenzene, DMF, 60°C, 4h, 58%; d) allyl isothiocyanate, AcOH, EtOH, 70°C, 16h, 27%; e) propargyl bromide or 12, Cs2CO3, 2-butanone, 70°C, 16h, 69–70%; f) Ts-Cl, pyridine, 0–4°C, 24h, 72%; g) nBuLi, −78°C, THF, 2h, then TBS-OTf, −78°C-RT, 1h, 63%.