A total synthesis of dilactarn (3) possessing the complete pentacyclic skeleton of the Ormosia alkaloids has been completed.Canadian Journal of Chemistry, 47, 509 (1969) The determination of the structure of the Orn~osia alkaloidjarnine by X-ray crystallography (1) led directly to the structure of ormosanine and, through a study of the reduction of the dehydrogenation product (1) (2, 3), to the structure and stereochemistry of additional alkaloids of this type (4). Since the alkaloid piptanthine (2) together with four isomeric bases has already been prepared by a controlled reduction of 1 (4) and since most of the stereochemical and functional variation in compounds of this class occurs in rings A, B, and E, it was deemed desirable to develop a synthetic approach in which ring E would be aromatic to the penultimate stage and in which ring A would be added last. The following total synthesis of the crystalline racemic dilactam (3) satisfies these requirements.The known compound (4) (5), m.p. 126-127", was reduced with Pd-C in ethanol to give an 80 % yield of the oily lactam ester (5), a mixture of at least two isomers.' Treatment of crude 5 with sodium hydride and ethyl acrylate in dimethyl formamide at 110' for 12 h gave the keto-ester (6), m.p. 155-156", in 53% yield. In order to establish its stereochemistry, 6 was hydrolyzed with 10% aqueous sulfuric acid to give 7, m.p. 173-176". Vigorous reduction of 7 with lithium aluminium hydride gave the corresponding hydroxyamine which showed strong Bohlmann bands (6) in the 2800 cm-' region of the i.r. spectrum (CHCI,). Based on previous study (4),'All reported conlpounds showed satisfactory spectral properties, including correct molecular ions in mass spectrometry. For brevity, only spectral data of special significance are given. All crystalline compounds gave correct elemental analysis. Unless otherwise stated, all oily conlpounds were purified by colunln chron~atography on silica gel and were homogeneous in thin-layer chromatography.this clearly establishes that the C,-H is cis to the C,-C, bridge. Treatment of 6 with selenium dioxide and acetic acid in boiling tert-butyl alcohol gave the unsaturated keto-ester (81, m.p.200-201°, in 78 % yield; this was then converted to ketone (9), m.p. 193-194", in 71 % yield on boiling with 10 % aqueous sulfuric acid.Since standard methods applied for construction of ring A using 7, 8, and 9 proved unpromising, the following novel synthetic application of the versatile photo-addition of olefins to a,P-unsaturated ketones2 was developed. Irradiation of 9 in vinyl acetate and tetrahydrofuran (Hanovia 100 W High-Pressure Hg vapor lamp, Pyrex filter) at 25" for 2 h gave a 60 % yield of a mixture composed of four isomers of acetate (10). Bromination of crude 10 with pyridinium bromide perbromide in glacial acetic acid gave a mixture of four bromo-ketones (11) in 78% yield. Treatment of crude 11 with sodium carbonate in aqueous methanol followed by chromatography on silica gel gave a 76% yield of pure keto-aldehyde (12), i.r. max...