Ring structures sugars, identified

They then prepared the completely methylated derivatives of adeno-gine . and guanosine by simultaneous deacetylation and methylation of the acetylated nucleosides. In this way, trimethyl-iV-methyl adenosine and trimethyl-A -methyl guanosine were formed, and isolated as the hydrochlorides. On hydrolysis of the adenosine derivative by means of dilute hydrochloric acid, 6-iV-methyladenine and trimethyl-D-ribo-furanose were isolated. The same trimethyl sugar was isolated from the methylated guanosine and was identified in each case by oxidation, first to trimethyl-7-D-ribonolactone and then to meso-dimethoxy succinic acid. It follows that the sugar component has the furanose ring-structure. 

Identify the aromatic heterocyclic ring structure contained in each of the following compounds, (a) Tolmetin, a drug used to lower blood sugar levels... 

Digoxin-like immunoreactive factors (DLIF) are present in serum and tissues of humans and animals.111 They were identified as genin glycosides, with one or two D-digitoxose units. Subtle structural differences were found in all three important portions of the molecule, the sugar, the lactone ring, and the sterol nucleus.112... 

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