Rosmarinine, the senecic acid ester of rosmarinecine, and a new alkaloid, angularine, the corresponding seneciphyllic acid ester, have been isolated from Senecio angulatus L. Assays of a number of hitherto unexamined species of the genus Senecio led to the observation that Senecio angulatus L., an ornamental plant native to South Africa and cultivated in Southern California, yields up to 1.5% (dry basis) of crystalline alkaloid. The crude alkaloid, isolated by the usual methods, showed variable melting point behavior from one preparation to another, and gave analytical results that agreed with a molecular formula within the limits of C₁₈H₂₆–₂₈N₂O₆. On paper chromatograms the substance showed an elongated spot which, by comparison with the well defined spots given under the same conditions by specimens of other, known, Senecio alkaloids, appeared to consist of two components. Hydrolysis of the unresolved alkaloid mixture gave the known pyrrolizidine base, rosmarinecine (I), identified by comparison with an authentic specimen and the preparation of its triacetate picrate, dibenzoate, anhydro base picrate, and anhydro base acetate picrate. These were identified by their properties and by direct comparison with authentic specimens. The other product from the hydrolysis of the alkaloid mixture was a crystalline acid that was first regarded as a single compound and which was at length found to be a mixture. Its melting point was 114–116°C when first isolated, but this altered upon repeated recrystallization, eventually broadening to about 116–129°C. Separation of the mixture into senecic (II) and seneciphyllic (III) acids was achieved by partition chromatography on a silicic acid column. Comparison of the infrared absorption spectrum of a mixture of equal parts of senecic and seneciphyllic acids, with that of the crude mixture of acids obtained from the unresolved alkaloid gave an indication that the plant contains roughly equal amounts of the corresponding alkaloids. The n.m.r. spectrum of the methyl esters of the acid mixture could be interpreted on the same grounds: the methyl groups of the ester groupings gave sharp 3H singlets at 6.46 and 6.50 τ and the methylene group of the seneciphyllic ester produced a doublet at 5.03 and 5.38 τ. Peaks (3H each) at 8.54 and 8.93 were due to the methyl groups on the hydroxylbearing carbon atoms of the seneciphyllic and senecic acid esters, respectively; and a doublet of reduced intensity is found at 9.16 τ, representing the CH-CH₃ (methyl) group of the senecic ester component of the mixture. Finally, the vinyl hydrogen atom of the ethylidene group (present in both acids) produced a signal (multiplet, 1H) at 4.26 τ, and the allylic methyl group gave a doublet at 8.09 τ. Separation of the crude alkaloid into the two pure components was at length accomplished by partition chromatography on a buffered Celite column. Elution with carbon tetrachloride-chloroform mixtures yielded, in earlier fractions, pure rosmarinine, identified by its properties and direct comparison (mixed melting point, infrared spectrum) with an authentic specimen; and, in later fractions, the new alkaloid, angularine. Angularine differs but little from rosmarinine in physical properties (melting point, optical rotation, chromatographic behavior), but the two compounds were clearly distinguished by elemental analysis, infrared absorption spectra, and by a large depression in the mixed melting point. A specimen of the crude, crystalline alkaloid mixture from S. angulatus was tested for hepatotoxic activity by Dr. K. K. Chen, Eli Lilly and Co., who reported that it produced no evidence of liver damage in experimental animals. This result agrees with that of a test performed earlier by Dr. Chen and his colleagues using a sample of pure rosmarinine supplied by Prof. F. L. Warren, and indicates that angularine, like rosmarinine, is devoid of hepatotoxic activity. A novel synthesis of 5-(γ-dimethylaminopropylidene)-5H-dibenzo[a,d]-10,11-dihydrocycloheptene and related systems based on the homoallylic rearrangement is presented. The effective psychotherapeutic drug amitriptyline (ELAVIL®) has been synthesized heretofore by the reaction between the Grignard reagent derived from γ-dimethylaminopropylchloride and 5H-dibenzo[a,d]-10,11-dihydro-5-cyclohepten-5-one. The growing importance of an alternative approach to amitriptyline, which would likewise provide versatility in the synthesis of γ-functionally related systems, constituted the basis for the present work. The condensation of 5H-dibenzo[a,d]-10,11-dihydrocyclohepten-5-one (I) with the Grignard reagent derived from cyclopropyl bromide afforded the crystalline cyclopropylcarbinol (II), m.p. 73–74°C, in high yield. The latter, on treatment with hydrogen chloride or hydrogen bromide in acetic acid solution, rearranged quantitatively to the corresponding 7-halopropenylcycloheptenes (III). The corresponding iodo derivative (III, X = I) was produced from the bromide (III, X = Br) with sodium iodide in refluxing acetone. The halo derivatives (III) were all highly crystalline individuals exhibiting characteristic absorption in the ultraviolet at 240 mμ (ε 14,000–17,000). Rearrangement of the derived cyclopropylcarbinol (II) with dilute perchloric acid in dioxane at 25°C proceeded smoothly with formation of the primary carbinol (IV) presumably by way of the homoallylic cation.