In the study of alkaloids from Glaucium Flavum Cr. var. Vestitum, a new non-phenolic aporphine alkaloid cataline was isolated, along with the known aporphine alkaloids thalicmidine (representing the first time this alkaloid has been found in the Papaveraceae from this plant) and dehydroglaucine. Chemical transformations of cataline (including O-acetylation, catalytic hydrogenolysis, and dehydration) and physical evidence (UV, IR, NMR, mass spectrum) led to the establishment of its structure as the second example of a 4-hydroxylated aporphine. The relative configuration at C-4 and C-6a was determined via spectroscopic analysis (intramolecularly hydrogen-bonded hydroxyl group, poorly resolved triplet of C-4 proton in NMR) and examination of Dreiding models. The absolute configuration (4s: 6a S) was proposed based on catalytic hydrogenolysis to (+)-glaucine (with known (S) configuration at C-6a, assuming no inversion at this position during the transformation). Treatment of cataline with 1:1 aqueous sulphuric acid at 90°C for about 5 hours afforded a mixture of didehydroglaucine, corunnine, and pontevedrine. Free oxygen oxidation of cataline and didehydroglaucine in hot hexamethylphosphoramide under free radical conditions yielded pontevedrine (main product), corunnine, and traces of a yellow compound, with further studies on these reactions and oxidizing agents ongoing.