SCHEME 4.
Synthesis of a fully protected monomer that can be converted to the N2-dG adduct after oligonucleotide synthesis.
Reaction conditions: a. Pd(OAc)2, Cs2CO3, BINAP, toluene (88%); b. TBAF, THF (80%); c. DMT-Cl, DMAP, TEA, pyridine (80%); d. 2-Cyanoethyl-N,N-diisopropylchlorophosphoramidite, TEA, CH2Cl2, r.t., 1h (60%).