28 硝酸タリウム(III)を用いるkaurene型ならびに関連ジテルペン類の酸化および転位反応

概要

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Applying a powerful oxidation ability and the "soft" character of Tl^<3+>, we carried out the following reactions and obtained some interesting results. 1) Allylic nitration: ent-16-Kaurene (1) on treatment with thallium (III) nitrate (TTN) in glyme gave allylic nitrates (2) and (3), while ent-15-kaurene (4) gave compound (5) as the major product, besides (2) and (3). Comparison of the reactivity of (1) with that of (4) and their reaction mechanism are discussed. A [3,3]-sigmatropic rearrangement between (2) and (3) is also described. 2) Oxidative rearrangement of a ketone: ent-17-Norkauran-16-one (18) on treatment with TTN in acetic acid afforded oxidative rearrangement products (19), (20a), (20b), and (21b). The structure determination of these products and the synthesis of their basic hydrocarbon skeleton (35) from the main product (19) have been carried out. 3) Selenoxide formation and Pummerer rearrangement: Diphenyl selenide (36) and phenyl benzyl selenide (38) were treated with TTN in THF to give the corresponding selenoxides in high yields. Applying these results, Pummererlike reaction was carried out. Thus, compound (43) derived from (18) on treatment with 3 mol. equivalents of TTN in THF gave diketone (44). The same reaction in methanol yielded compound (45).
天然有機化合物討論会の論文
1976-09-20