Gold Mono- and Bis-N-heterocyclic Carbenes Based on mRNA cap0

Eukaryotic mRNA contains a cap structure that consists of a methylated guanosine (mRNA cap0) connected to the first transcribed nucleotide by an unusual 5'-5'-triphosphate bridge. Herein, we describe the synthesis of gold mono- and bis-N-heterocyclic carbenes derived from 7-methylguanosine at room temperature. The compounds can be synthesized directly from 7-methylguanosine, and the synthesis does not require the protection of the hydroxyl groups of the ribose to be effective. The synthesis was also performed successfully with the acetate protected nucleoside, but deprotection of the sugar was not effective. The compounds are stable under air, both in the solid state and in solution. Gold monocarbene 1 retains its ability to form Watson-Crick base pairs with cytosine, without interference of the acetate protecting groups.