Isomeric Lactones Research Articles

Chemistry of Australian Lichens. II. A New Depsidone from Parmelia conspersa (Ehrh.) Ach

A new compound, norlobaridone, from Parmelia conspersa is shown to have structure Ia by conversion of its monomethyl ether (lobaridone (Ib)) into lobariol (IIb). The depsidone ring is readily cleaved by basic reagents to give products containing a new cyclic system and including an isomeric γ-enol lactone (IIIa), norlobariol (IIa), and the oxime anhydride (IVa) of the latter. Ultraviolet and infra-red spectra support structural assignments. Norlobaridone (Ia) presents an exception to the acetate theory of biogenesis in the position of its ketonic oxygen atom.

A synthesis of the lactone of 5‐pyridoxic acid

AbstractThe reduction of dimethyl 2‐methyl‐3‐hydroxypyridine 4,5‐dicarboxylate (I) with sodium borohydride and aluminium chloride gives no pyridoxol but a precursor i.e. the lactone II, corresponding to 5‐pyridoxic acid. No isomeric lactone (III) corresponding to 4‐pyridoxic acid was isolated.

Isomeric Lactone Pairs Related to Cyclohexanone-2-acetic Acid1

Isomeric Lactone Pairs Related to Cyclohexanone-2-acetic Acid¹

LXXXIV.—Constitutional studies in the monocarboxylic acids derived from sugars. Part IV. The isomeric lactones obtained from arabinose

LXXXIV.—Constitutional studies in the monocarboxylic acids derived from sugars. Part IV. The isomeric lactones obtained from arabinose