Novel Methide Polymerization Reactions

SCHEME 7.6 Catalytic reductive alkylation of guanosine with 13C at the C-10 position of WV-15. The inset shows generation of the iminium methide upon reduction. 

We succeeded in isolating the same adduct reported by Maliepaard et al. in trace quantities, but a 13C-NMR spectrum of the crude reaction mixture revealed the presence of hundreds of additional products (Fig. 7.4). The chemical shift of the guanosine 2-amino adduct (35.4 ppm) is not obvious in this spectrum. The bands of chemical shifts centered at 65 and 55 ppm correspond to structures with oxygen attachment to the C-10 center, but the band of products centered at 28 ppm represented unknown structures. 

CHARACTERIZING QUINONE METHIDES BY SPECTRAL GLOBAL FITTING 

SCHEME 7.7 Products of reductive activation of a simplified WV-15 analogue. The 13C labels are designated with asterisks ( ). 

FIGURE 7.5 13C-NMR spectrum of the pentamer showing four methylene linkages and a methyl terminus. 

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