Trimethylsilyl derivatives of N4-Boc-cytosine and their effect on I2-mediated nucleosidation of O-MTM ethers

Mono- and bis(trimethylsilyl) derivatives of N4-Boc-cytosine were synthesized and characterized by 1H NMR. Only the mono(trimethylsilyl)-N4-Boc-cytosine participates in the iodine-mediated nucleosidation of N-Fmoc-O-methylthiomethyl serine benzyl ester to produce the cytosine nucleoamino acid, while the bis(trimethylsilyl) derivative failed to give any product. A tentative mechanistic explanation is proposed.