The total synthesis of the first Lycopodium alkaloid annotinine in the optically active form is described. The key step in this synthesis was the photochemical addition of allene to the tricyclic vinylogous imide (3) which yielded the photoadduct (6).
A stereoselective β-glycosidation of digitoxose and digitoxigenin involving a 1–3 participation of a urethane group is described. The conversion of digitoxin (10) to its furyl derivative 11 and the rcoxidation of 11 to digitoxin and isodigitoxin (12), respectively, in high yield is reported for the first time. This is of fundamental importance for the use of the new glycosidation method in the total synthesis of digitoxin and its analogues.
Pithecolobine, C22H46N4O2, has a lactam group, one primary and two secondary amino groups, and a hydroxyl group. Lithium aluminum hydride converts it into a monocyclic saturated compound, desoxypithecolobine, C22H48N4. Hofmann degradation of this compound gives tetramethylputrescine, trimethyl amine, a doubly unsaturated base C16H31N with a terminal methylene group, and a base C16H34N2. Heating with selenium yields a hydrocarbon, C12;H24–26, with a sequence of six or more CH2 groups. A crystalline oxygen-free compound with two nitrogens (m.p.94 °C.) is also obtained, the ultraviolet spectrum of which is almost identical with aminopyridine.
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