Methylation of desmethyl analogue of Y nucleosides. Wyosine from guanosine

Abstract
Wyoslne la. one of the fluorescent hypermodified Y nucleosides found In tRNAsPhe, was synthesized chemically from its biogenetic precursor guanosine 2. The route involved transformation of 2. into the tricyclic structure 3a and subsequent methylation at N-4. The major products of various methylation procedures were isomers of wyosine, methylated at H-5 (5b) or at H-l (4). Mesoionic compound 4 is a new analogue of 7-methylguanosine 5, modified nucl-eoside occuring in the unique positions in transfer, messenger and ribosomal HNAs. The chromatographio and spectral ohaxacteristios of wyosine and its isomers is given.