Scheme 2. On-DNA “Recipe” Synthesis toward 10 Using the Photocleavable Linker.

Reagents and conditions: (a) DMT-MM, DMA, pH 9.4 sodium borate buffer, rt, 2 h; (b) Pd(PPh₃)₄ in ACN, Na₂CO₃, DMA, water, 80 °C, 5 h; (c) NaCNBH₃, DMA, pH 5.5 sodium phosphate buffer, 60 °C, 16 h; (d) hν 365 nm, 4:1 (H₂O:MeOH), 0 °C, 1 h. (%RBA = relative binding affinity by AS-MS.)